Author name code: cho
ADS astronomy entries on 2022-09-14
author:"Cho, Kyung Suk"
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Title: Interferometric imaging, and beam-formed study of a moving
Type IV Radio burst with LOFAR
Authors: Liu, Hongyu; Zucca, Pietro; Cho, Kyung-Suk; Kumari, Anshu;
Zhang, Peijin; Magdalenic, Jasmina; Kim, Rok-Soon; Kim, Sujin;
Kang, Juhyung
Bibcode: 2022arXiv220813670L
Altcode:
Type IV radio burst has been studied for over 50 years. However, the
specifics of the radio emission mechanisms is still an open question. In
order to provide more information about the emission mechanisms, we
studied a moving type IV radio burst with fine structures (spike group)
by using the high resolution capability of Low-Frequency Array (LOFAR)
on Aug 25, 2014\textbf{ (SOLA-D-21-00188)}. We present a comparison of
Nançay RadioHeliograph (NRH) and the first LOFAR imaging data of type
IV radio burst. The degree of circular polarization (DCP) is calculated
at frequencies in the range 20$\sim$180 MHz using LOFAR data, and it
was found that the value of DCP gradually increased during the event,
with values of 10\%$\sim$20\%. LOFAR interferometric data were combined
with white light observations in order to track the propagation of this
type IV. The kinematics shows a westward motion of the radio sources,
slower than the CME leading edge. The dynamic spectrum of LOFAR shows a
large number of fine structures with duration of less than 1s and high
brightness temperature ($T_\mathrm{B}$), i.e. $10^{12}$$\sim$$10^{13}$
K. The gradual increase of DCP supports gyrosynchrotron emission as the
most plausible mechanism for the type IV. However, coherent emissions
such as Electron Cyclotron Maser (ECM) instability can be responsible
for small scale fine structures. Countless fine structures altogether
were responsible for such high $T_\mathrm{B}$.
Title: Reconstruction of Coronal Magnetic Fields Using a
Poloidal-Toroidal Representation
Authors: Yi, Sibaek; Choe, G. S.; Cho, Kyung-Suk; Solanki, Sami K.;
Büchner, Jörg
Bibcode: 2022arXiv220607189Y
Altcode:
A new method for reconstruction of coronal magnetic fields as force-free
fields (FFFs) is presented. Our method employs poloidal and toroidal
functions to describe divergence-free magnetic fields. This magnetic
field representation naturally enables us to implement the boundary
conditions at the photospheric boundary, i.e., the normal magnetic field
and the normal current density there, in a straightforward manner. At
the upper boundary of the corona, a source-surface condition can be
employed, which accommodates magnetic flux imbalance at the bottom
boundary. Although our iteration algorithm is inspired by extant
variational methods, it is non-variational and requires much less
iteration steps than most of them. The computational code based on our
new method is tested against the analytical FFF solutions by Titov &
Démoulin (1999). It is found to excel in reproducing a tightly wound
flux rope, a bald patch and quasi-separatrix layers with a hyperbolic
flux tube.
Title: Kink Oscillation of a Flux Rope During a Failed Solar Eruption
Authors: Kumar, Pankaj; Nakariakov, Valery M.; Karpen, Judith T.;
Richard DeVore, C.; Cho, Kyung-Suk
Bibcode: 2022ApJ...932L...9K
Altcode: 2022arXiv220503480K
We report a decaying kink oscillation of a flux rope during a confined
eruptive flare, observed off the solar limb by the Solar Dynamics
Observatory's Atmospheric Imaging Assembly (AIA), which lacked a
detectable white-light coronal mass ejection. The erupting flux rope
underwent kinking, rotation, and apparent leg-leg interaction during the
event. The oscillations were observed simultaneously in multiple AIA
channels at 304, 171, and 193 Å, indicating that multithermal plasma
was entrained in the rope. After reaching the overlying loops in the
active region, the flux rope exhibited large-amplitude, decaying kink
oscillations with an apparent initial amplitude of 30 Mm, a period of
about 16 minutes, and a decay time of about 17 minutes. We interpret
these oscillations as a fundamental standing kink mode of the flux
rope. The oscillation polarization has a clear vertical component,
while the departure of the detected waveform from a sinusoidal signal
suggests that the oscillation could be circularly or elliptically
polarized. The estimated kink speed is 1080 km s-1,
corresponding to an Alfvén speed of about 760 km s-1. This
speed, together with the estimated electron density in the rope from our
differential emission measure analysis, n e ≍ (1.5-2.0)
× 109 cm-3, yields a magnetic-field strength of
about 15 G. To the best of our knowledge, decaying kink oscillations of
a flux rope with nonhorizontal polarization during a confined eruptive
flare have not been reported before. These oscillations provide unique
opportunities for indirect measurements of the magnetic-field strength
in low-coronal flux ropes during failed eruptions.
Title: Application of NASA core Flight System to Telescope Control
Software for 2017 Total Solar Eclipse Observation
Authors: Park, Jongyeob; Lee, Jae-Ok; Kim, Jihun; Bong, Su-Chan; Cho,
Kyung-Suk; Choi, Seonghwan; Jang, Bi-Ho; Park, Young-Deuk; Moon,
Yong-Jae; Baek, Ji-Hye; Yang, Heesu; Kim, Sujin; Kim, Yeon-Han;
Timmons, Elizabeth; Swinski, Joseph-paul A.
Bibcode: 2022PASP..134c4504P
Altcode:
The core Flight System (cFS), developed by NASA, is a reusable
software framework and a set of pluggable software applications
that take advantage of the rich heritage of NASA's successful space
missions. We applied the cFS to the development of telescope control
software for the observation of the 2017 total solar eclipse. Four
main modules were developed: imaging control, mechanism control,
data handling, and automated observation. Other modules, such as
communication and scheduler, were reused from the cFS. Using an
integrated observation system, we successfully observed the total solar
eclipse, in which the linearly polarized brightness of the solar corona
and sky background were measured at four different wavelengths. In this
study, we demonstrated the usefulness of the cFS to develop telescope
control software through an eclipse observation system, the so-called
DICE (DIagnostic Coronagraph Experiment) mission. Our experience
and knowledge of the cFS were expanded to a flight software BITSE
(Balloon-borne Investigation of Temperature and Speed of Electrons in
the corona), the high-altitude scientific balloon mission in 2019. We
plan to apply this approach to future solar coronagraph observations,
such as CODEX (COronal Diagnostic EXperiment), on the International
Space Station. We expect that the cFS can also be applied in telescope
control software for ground-and space-based observations.
Title: Building on Stories to Engage Children in Spatial Thinking
Authors: Plummer, J.; Cho, K.; Botch, M.
Bibcode: 2021ASPC..531...14P
Altcode:
Early development of spatial thinking has the potential to increase
children's achievement in science and math, and may increase children's
potential for STEM careers. Spatial thinking involves how we manipulate
information, both mentally and through representations in the world
around us, to understand the location of objects, their relative
locations, how they move with respect to each other, and estimating
their shapes and sizes. One promising, though under-researched
strategy to improve STEM learning is the use of storytelling in
programs for young learners. This interactive session will begin by
introducing participants to research on how stories shape learning
and how this can be leveraged to engage learners with strategies that
support spatial thinking. We will then introduce participants to a
new program for early childhood audiences that combine a children's
storybook ("Lunar Craters" by Kyungjin Cho) with activities designed to
support spatial thinking through the use of spatial language, gestures,
object-manipulation, and whole-body movement. We will briefly share
results from a recent study completed with 3-5 year-old audiences in
preschool and museum settings to illustrate how story and story-driven
programs may support children's spatial thinking. Finally, participants
will have the opportunity to try their hand at planning for spatial
thinking with story-based programming. Participants will be provided
with an astronomy-based storybook narrative (appropriate for PreK or
elementary-age students) and will engage collaboratively to consider
ways to use the narrative as inspiration for activities designed to
engage children in spatial thinking.
Title: Observational Kinematic Characteristics of Blobs in Solar
Coronal Helmet and Pseudo Streamers
Authors: Lee, Jae-Ok; Cho, Kyung-Suk; An, Junmo; Lee, Hwanhee; Seough,
Jungjoon; Kim, Yeon-Han; Kumar, Pankaj
Bibcode: 2021ApJ...920L...6L
Altcode:
We examine two helmet and two pseudo streamers (HSs and PSs) observed on
2018 and 2019. The HSs (PSs) have dark coronal cavities and stretched
loop structures (twin coronal cavities and narrow plasma sheet) at
their bases, which are well observed in K-Coronagraph (K-Cor). Their
outer-corona structures (top of core, cusp, and stalk) are also
clearly identified in LASCO-C2. By investigating LASCO-C2 images,
we find the following characteristics. (1) Blobs persistently move
outward along the centers of HSs and PSs as well as their legs until
the base of a stalk. We also detect outward-moving blobs along their
outsides. (2) Blobs along the HS centers formed below tops of cores
(~2.6 R⊙), while the other HS and PS blobs might be
generated below 2.0 R⊙. (3) HS blob speeds are generally
similar to or smaller than the solar wind speed based on Parker's
model, while PS ones are larger. (4) HS (PS) blob speeds along the
streamer centers are slightly smaller (larger) than those along the
streamer legs, might be explained by the expansion-factor model. The
blob speeds inside streamer structures (centers and legs) are larger
than outside ones closer to solar equator, similar to typical solar
wind speed distributions at solar minimum. (5) Several blobs along the
HS centers only show sudden speed jumps at streamer cusps. These might
be caused by sunward tension forces of overlying stretched closed fields
and/or bidirectional outflows by magnetic reconnections in the cusps.
Title: Searching for solar KDAR with DUNE
Authors: Abed Abud, A.; Abi, B.; Acciarri, R.; Acero, M. A.; Adames,
M. R.; Adamov, G.; Adams, D.; Adinolfi, M.; Aduszkiewicz, A.; Aguilar,
J.; Ahmad, Z.; Ahmed, J.; Ali-Mohammadzadeh, B.; Alion, T.; Allison,
K.; Alonso Monsalve, S.; Alrashed, M.; Alt, C.; Alton, A.; Amedo,
P.; Anderson, J.; Andreopoulos, C.; Andreotti, M.; Andrews, M. P.;
Andrianala, F.; Andringa, S.; Anfimov, N.; Ankowski, A.; Antoniassi,
M.; Antonova, M.; Antoshkin, A.; Antusch, S.; Aranda-Fernandez, A.;
Ariga, A.; Arnold, L. O.; Arroyave, M. A.; Asaadi, J.; Asquith, L.;
Aurisano, A.; Aushev, V.; Autiero, D.; Ayala-Torres, M.; Azfar, F.;
Back, A.; Back, H.; Back, J. J.; Backhouse, C.; Baesso, P.; Bagaturia,
I.; Bagby, L.; Balashov, N.; Balasubramanian, S.; Baldi, P.; Baller,
B.; Bambah, B.; Barao, F.; Barenboim, G.; Barker, G. J.; Barkhouse,
W.; Barnes, C.; Barr, G.; Barranco Monarca, J.; Barros, A.; Barros,
N.; Barrow, J. L.; Basharina-Freshville, A.; Bashyal, A.; Basque, V.;
Belchior, E.; Battat, J. B. R.; Battisti, F.; Bay, F.; Bazo Alba,
J. L.; Beacom, J. F.; Bechetoille, E.; Behera, B.; Bellantoni, L.;
Bellettini, G.; Bellini, V.; Beltramello, O.; Belver, D.; Benekos,
N.; Benitez Montiel, C.; Bento Neves, F.; Berger, J.; Berkman, S.;
Bernardini, P.; Berner, R. M.; Berns, H.; Bertolucci, S.; Betancourt,
M.; Betancur Rodríguez, A.; Bevan, A.; Bezerra, T. J. C.; Bhatnagar,
V.; Bhattacharjee, M.; Bhuller, S.; Bhuyan, B.; Biagi, S.; Bian, J.;
Biassoni, M.; Biery, K.; Bilki, B.; Bishai, M.; Bitadze, A.; Blake,
A.; Blaszczyk, F. D. M.; Blazey, G. C.; Blucher, E.; Boissevain, J.;
Bolognesi, S.; Bolton, T.; Bomben, L.; Bonesini, M.; Bongrand, M.;
Bonini, F.; Booth, A.; Booth, C.; Boran, F.; Bordoni, S.; Borkum, A.;
Boschi, T.; Bostan, N.; Bour, P.; Bourgeois, C.; Boyd, S. B.; Boyden,
D.; Bracinik, J.; Braga, D.; Brailsford, D.; Branca, A.; Brandt,
A.; Bremer, J.; Brew, C.; Brianne, E.; Brice, S. J.; Brizzolari, C.;
Bromberg, C.; Brooijmans, G.; Brooke, J.; Bross, A.; Brunetti, G.;
Brunetti, M.; Buchanan, N.; Budd, H.; Butorov, I.; Cagnoli, I.; Caiulo,
D.; Calabrese, R.; Calafiura, P.; Calcutt, J.; Calin, M.; Calvez, S.;
Calvo, E.; Caminata, A.; Campanelli, M.; Cankocak, K.; Caratelli, D.;
Carini, G.; Carlus, B.; Carneiro, M. F.; Carniti, P.; Caro Terrazas,
I.; Carranza, H.; Carroll, T.; Castaño Forero, J. F.; Castillo,
A.; Castromonte, C.; Catano-Mur, E.; Cattadori, C.; Cavalier, F.;
Cavanna, F.; Centro, S.; Cerati, G.; Cervelli, A.; Cervera Villanueva,
A.; Chalifour, M.; Chappell, A.; Chardonnet, E.; Charitonidis, N.;
Chatterjee, A.; Chattopadhyay, S.; Chen, H.; Chen, M.; Chen, Y.; Chen,
Z.; Cheon, Y.; Cherdack, D.; Chi, C.; Childress, S.; Chiriacescu,
A.; Chisnall, G.; Cho, K.; Choate, S.; Chokheli, D.; Chong, P. S.;
Choubey, S.; Christensen, A.; Christian, D.; Christodoulou, G.;
Chukanov, A.; Chung, M.; Church, E.; Cicero, V.; Clarke, P.; Coan,
T. E.; Cocco, A. G.; Coelho, J. A. B.; Conley, E.; Conley, R.; Conrad,
J. M.; Convery, M.; Copello, S.; Corwin, L.; Valentim, R.; Cremaldi,
L.; Cremonesi, L.; Crespo-Anadón, J. I.; Crisler, M.; Cristaldo,
E.; Cross, R.; Cudd, A.; Cuesta, C.; Cui, Y.; Cussans, D.; Dalager,
O.; da Motta, H.; Da Silva Peres, L.; David, C.; David, Q.; Davies,
G. S.; Davini, S.; Dawson, J.; De, K.; Debbins, P.; De Bonis, I.;
Decowski, M. P.; de Gouvêa, A.; De Holanda, P. C.; De Icaza Astiz,
I. L.; Deisting, A.; De Jong, P.; Delbart, A.; Delepine, D.; Delgado,
M.; Dell'Acqua, A.; De Lurgio, P.; de Mello Neto, J. R. T.; DeMuth,
D. M.; Dennis, S.; Densham, C.; Deptuch, G. W.; De Roeck, A.; De
Romeri, V.; De Souza, G.; Devi, R.; Dharmapalan, R.; Dias, M.; Diaz,
F.; Díaz, J. S.; Di Domizio, S.; Di Giulio, L.; Ding, P.; Di Noto,
L.; Distefano, C.; Diurba, R.; Diwan, M.; Djurcic, Z.; Doering,
D.; Dolan, S.; Dolek, F.; Dolinski, M. J.; Domine, L.; Douglas, D.;
Douillet, D.; Drake, G.; Drielsma, F.; Duarte, L.; Duchesneau, D.;
Duffy, K.; Dunne, P.; Durkin, T.; Duyang, H.; Dvornikov, O.; Dwyer,
D. A.; Dyshkant, A. S.; Eads, M.; Earle, A.; Edmunds, D.; Eisch, J.;
Emberger, L.; Emery, S.; Ereditato, A.; Erjavec, T.; Escobar, C. O.;
Eurin, G.; Evans, J. J.; Ewart, E.; Ezeribe, A. C.; Fahey, K.; Falcone,
A.; Fani', M.; Farnese, C.; Farzan, Y.; Fedoseev, D.; Felix, J.; Feng,
Y.; Fernandez-Martinez, E.; Fernandez Menendez, P.; Fernandez Morales,
M.; Ferraro, F.; Fields, L.; Filip, P.; Filthaut, F.; Fiorentini, A.;
Fiorini, M.; Fitzpatrick, R. S.; Flanagan, W.; Fleming, B.; Flight, R.;
Forero, D. V.; Fowler, J.; Fox, W.; Franc, J.; Francis, K.; Franco,
D.; Freeman, J.; Freestone, J.; Fried, J.; Friedland, A.; Fuentes
Robayo, F.; Fuess, S.; Furic, I. K.; Furmanski, A. P.; Gabrielli,
A.; Gago, A.; Gallagher, H.; Gallas, A.; Gallego-Ros, A.; Gallice,
N.; Galymov, V.; Gamberini, E.; Gamble, T.; Ganacim, F.; Gandhi, R.;
Gandrajula, R.; Gao, F.; Gao, S.; Garcia B., A. C.; Garcia-Gamez, D.;
García-Peris, A.; Gardiner, S.; Gastler, D.; Gauvreau, J.; Ge, G.;
Gelli, B.; Gendotti, A.; Gent, S.; Ghorbani-Moghaddam, Z.; Giammaria,
P.; Giammaria, T.; Gibin, D.; Gil-Botella, I.; Gilligan, S.; Girerd,
C.; Giri, A. K.; Gnani, D.; Gogota, O.; Gold, M.; Gollapinni, S.;
Gollwitzer, K.; Gomes, R. A.; Gomez Bermeo, L. V.; Gomez Fajardo,
L. S.; Gonnella, F.; Gonzalez-Cuevas, J. A.; Gonzalez Diaz, D.;
Gonzalez-Lopez, M.; Goodman, M. C.; Goodwin, O.; Goswami, S.; Gotti,
C.; Goudzovski, E.; Grace, C.; Graham, M.; Gran, R.; Granados, E.;
Granger, P.; Grant, A.; Grant, C.; Gratieri, D.; Green, P.; Greenler,
L.; Greer, J.; Grenard, J.; Griffith, W. C.; Groh, M.; Grudzinski,
J.; Grzelak, K.; Gu, W.; Guardincerri, E.; Guarino, V.; Guarise,
M.; Guenette, R.; Guerard, E.; Guerzoni, M.; Guglielmi, A.; Guo, B.;
Guthikonda, K. K.; Gutierrez, R.; Guzowski, P.; Guzzo, M. M.; Gwon,
S.; Ha, C.; Habig, A.; Hadavand, H.; Haenni, R.; Hahn, A.; Haiston,
J.; Hamacher-Baumann, P.; Hamernik, T.; Hamilton, P.; Han, J.; Harris,
D. A.; Hartnell, J.; Harton, J.; Hasegawa, T.; Hasnip, C.; Hatcher,
R.; Hatfield, K. W.; Hatzikoutelis, A.; Hayes, C.; Hayrapetyan,
K.; Hays, J.; Hazen, E.; He, M.; Heavey, A.; Heeger, K. M.; Heise,
J.; Hennessy, K.; Henry, S.; Hernandez Morquecho, M. A.; Herner,
K.; Hertel, L.; Hewes, J.; Higuera, A.; Hill, T.; Hillier, S. J.;
Himmel, A.; Hirsch, L. R.; Ho, J.; Hoff, J.; Holin, A.; Hoppe, E.;
Horton-Smith, G. A.; Hostert, M.; Hourlier, A.; Howard, B.; Howell,
R.; Hristova, I.; Hronek, M. S.; Huang, J.; Huang, J.; Hugon, J.;
Iles, G.; Ilic, N.; Iliescu, A. M.; Illingworth, R.; Ingratta, G.;
Ioannisian, A.; Isenhower, L.; Itay, R.; Izmaylov, A.; Jackson, C. M.;
Jain, V.; James, E.; Jang, W.; Jargowsky, B.; Jediny, F.; Jena, D.;
Jeong, Y. S.; Jesús-Valls, C.; Ji, X.; Jiang, L.; Jiménez, S.; Jipa,
A.; Johnson, R.; Johnston, N.; Jones, B.; Jones, S. B.; Judah, M.;
Jung, C. K.; Junk, T.; Jwa, Y.; Kabirnezhad, M.; Kaboth, A.; Kadenko,
I.; Kalra, D.; Kakorin, I.; Kalitkina, A.; Kamiya, F.; Kaneshige, N.;
Karagiorgi, G.; Karaman, G.; Karcher, A.; Karolak, M.; Karyotakis,
Y.; Kasai, S.; Kasetti, S. P.; Kashur, L.; Kazaryan, N.; Kearns,
E.; Keener, P.; Kelly, K. J.; Kemp, E.; Kemularia, O.; Ketchum, W.;
Kettell, S. H.; Khabibullin, M.; Khotjantsev, A.; Khvedelidze, A.;
Kim, D.; King, B.; Kirby, B.; Kirby, M.; Klein, J.; Koehler, K.;
Koerner, L. W.; Kohn, S.; Koller, P. P.; Kolupaeva, L.; Korablev,
D.; Kordosky, M.; Kosc, T.; Kose, U.; Kostelecký, V. A.; Kothekar,
K.; Krennrich, F.; Kreslo, I.; Kropp, W.; Kudenko, Y.; Kudryavtsev,
V. A.; Kulagin, S.; Kumar, J.; Kumar, P.; Kunze, P.; Kuruppu, C.;
Kus, V.; Kutter, T.; Kvasnicka, J.; Kwak, D.; Lambert, A.; Land,
B. J.; Lande, K.; Lane, C. E.; Lang, K.; Langford, T.; Langstaff,
M.; Larkin, J.; Lasorak, P.; Last, D.; Lastoria, C.; Laundrie, A.;
Laurenti, G.; Lawrence, A.; Lazanu, I.; LaZur, R.; Lazzaroni, M.; Le,
T.; Leardini, S.; Learned, J.; LeBrun, P.; LeCompte, T.; Lee, C.; Lee,
S. Y.; Lehmann Miotto, G.; Lehnert, R.; Leigui de Oliveira, M. A.;
Leitner, M.; Lepin, L. M.; Li, L.; Li, S. W.; Li, T.; Li, Y.; Liao,
H.; Lin, C. S.; Lin, Q.; Lin, S.; Ling, J.; Lister, A.; Littlejohn,
B. R.; Liu, J.; Lockwitz, S.; Loew, T.; Lokajicek, M.; Lomidze, I.;
Long, K.; Loo, K.; Lord, T.; LoSecco, J. M.; Louis, W. C.; Lu, X. -G.;
Luk, K. B.; Luo, X.; Luppi, E.; Lurkin, N.; Lux, T.; Luzio, V. P.;
MacFarlane, D.; Machado, A. A.; Machado, P.; Macias, C. T.; Macier,
J. R.; Maddalena, A.; Madera, A.; Madigan, P.; Magill, S.; Mahn,
K.; Maio, A.; Major, A.; Maloney, J. A.; Mandrioli, G.; Mandujano,
R. C.; Maneira, J.; Manenti, L.; Manly, S.; Mann, A.; Manolopoulos,
K.; Manrique Plata, M.; Manyam, V. N.; Manzanillas, L.; Marchan, M.;
Marchionni, A.; Marciano, W.; Marfatia, D.; Mariani, C.; Maricic,
J.; Marie, R.; Marinho, F.; Marino, A. D.; Marsden, D.; Marshak,
M.; Marshall, C. M.; Marshall, J.; Marteau, J.; Martin-Albo, J.;
Martinez, N.; Martinez Caicedo, D. A.; Martynenko, S.; Mascagna,
V.; Mason, K.; Mastbaum, A.; Masud, M.; Matichard, F.; Matsuno, S.;
Matthews, J.; Mauger, C.; Mauri, N.; Mavrokoridis, K.; Mawby, I.;
Mazza, R.; Mazzacane, A.; Mazzucato, E.; McAskill, T.; McCluskey,
E.; McConkey, N.; McFarland, K. S.; McGrew, C.; McNab, A.; Mefodiev,
A.; Mehta, P.; Melas, P.; Mena, O.; Menary, S.; Mendez, H.; Mendez,
P.; M, D. P.; Menegolli, A.; Meng, G.; Messier, M. D.; Metcalf, W.;
Mettler, T.; Mewes, M.; Meyer, H.; Miao, T.; Michna, G.; Miedema, T.;
Mikola, V.; Milincic, R.; Miller, G.; Miller, W.; Mills, J.; Milne,
C.; Mineev, O.; Miranda, O. G.; Miryala, S.; Mishra, C. S.; Mishra,
S. R.; Mislivec, A.; Mladenov, D.; Mocioiu, I.; Moffat, K.; Moggi,
N.; Mohanta, R.; Mohayai, T. A.; Mokhov, N.; Molina, J.; Molina Bueno,
L.; Montagna, E.; Montanari, A.; Montanari, C.; Montanari, D.; Montano
Zetina, L. M.; Moon, J.; Moon, S. H.; Mooney, M.; Moor, A. F.; Moreno,
D.; Morris, C.; Mossey, C.; Motuk, E.; Moura, C. A.; Mousseau, J.;
Mouster, G.; Mu, W.; Mualem, L.; Mueller, J.; Muether, M.; Mufson,
S.; Muheim, F.; Muir, A.; Mulhearn, M.; Munford, D.; Muramatsu,
H.; Murphy, S.; Musser, J.; Nachtman, J.; Nagu, S.; Nalbandyan, M.;
Nandakumar, R.; Naples, D.; Narita, S.; Nath, A.; Navas-Nicolás,
D.; Navrer-Agasson, A.; Nayak, N.; Nebot-Guinot, M.; Negishi, K.;
Nelson, J. K.; Nesbit, J.; Nessi, M.; Newbold, D.; Newcomer, M.;
Newhart, D.; Newton, H.; Nichol, R.; Nicolas-Arnaldos, F.; Niner, E.;
Nishimura, K.; Norman, A.; Norrick, A.; Northrop, R.; Novella, P.;
Nowak, J. A.; Oberling, M.; Ochoa-Ricoux, J. P.; Olivares Del Campo,
A.; Olivier, A.; Olshevskiy, A.; Onel, Y.; Onishchuk, Y.; Ott, J.;
Pagani, L.; Pakvasa, S.; Palacio, G.; Palamara, O.; Palestini, S.;
Paley, J. M.; Pallavicini, M.; Palomares, C.; Palomino-Gallo, J. L.;
Panduro Vazquez, W.; Pantic, E.; Paolone, V.; Papadimitriou, V.;
Papaleo, R.; Papanestis, A.; Paramesvaran, S.; Parke, S.; Parozzi,
E.; Parsa, Z.; Parvu, M.; Pascoli, S.; Pasqualini, L.; Pasternak,
J.; Pater, J.; Patrick, C.; Patrizii, L.; Patterson, R. B.; Patton,
S. J.; Patzak, T.; Paudel, A.; Paulos, B.; Paulucci, L.; Pavlovic,
Z.; Pawloski, G.; Payne, D.; Pec, V.; Peeters, S. J. M.; Pennacchio,
E.; Penzo, A.; Peres, O. L. G.; Perry, J.; Pershey, D.; Pessina,
G.; Petrillo, G.; Petta, C.; Petti, R.; Pia, V.; Piastra, F.;
Pickering, L.; Pietropaolo, F.; Plunkett, R.; Poling, R.; Pons, X.;
Poonthottathil, N.; Poppi, F.; Pordes, S.; Porter, J.; Potekhin,
M.; Potenza, R.; Potukuchi, B. V. K. S.; Pozimski, J.; Pozzato,
M.; Prakash, S.; Prakash, T.; Prest, M.; Prince, S.; Psihas, F.;
Pugnere, D.; Qian, X.; Queiroga Bazetto, M. C.; Raaf, J. L.; Radeka,
V.; Rademacker, J.; Radics, B.; Rafique, A.; Raguzin, E.; Rai, M.;
Rajaoalisoa, M.; Rakhno, I.; Rakotonandrasana, A.; Rakotondravohitra,
L.; Ramachers, Y. A.; Rameika, R.; Ramirez Delgado, M. A.; Ramson,
B.; Rappoldi, A.; Raselli, G.; Ratoff, P.; Raut, S.; Razakamiandra,
R. F.; Rea, E.; Real, J. S.; Rebel, B.; Reggiani-Guzzo, M.; Rehak,
T.; Reichenbacher, J.; Reitzner, S. D.; Rejeb Sfar, H.; Renshaw, A.;
Rescia, S.; Resnati, F.; Reynolds, A.; Ribas, M.; Riboldi, S.; Riccio,
C.; Riccobene, G.; Rice, L. C. J.; Ricol, J.; Rigamonti, A.; Rigaut,
Y.; Rivera, D.; Robert, A.; Rochester, L.; Roda, M.; Rodrigues, P.;
Rodriguez Alonso, M. J.; Rodriguez Bonilla, E.; Rodriguez Rondon,
J.; Rosauro-Alcaraz, S.; Rosenberg, M.; Rosier, P.; Roskovec, B.;
Rossella, M.; Rossi, M.; Rott, C.; Rout, J.; Roy, P.; Roy, S.; Rubbia,
A.; Rubbia, C.; Rubio, F. C.; Russell, B.; Ruterbories, D.; Rybnikov,
A.; Saa-Hernandez, A.; Saakyan, R.; Sacerdoti, S.; Safford, T.; Sahu,
N.; Sala, P.; Samios, N.; Samoylov, O.; Sanchez, M. C.; Sandberg,
V.; Sanders, D. A.; Sankey, D.; Santana, S.; Santos-Maldonado, M.;
Saoulidou, N.; Sapienza, P.; Sarasty, C.; Sarcevic, I.; Savage, G.;
Savinov, V.; Scaramelli, A.; Scarff, A.; Scarpelli, A.; Schaffer, T.;
Schellman, H.; Schifano, S.; Schlabach, P.; Schmitz, D.; Scholberg, K.;
Schukraft, A.; Segreto, E.; Selyunin, A.; Senise, C. R.; Sensenig, J.;
Seoane, M.; Seong, I.; Sergi, A.; Sgalaberna, D.; Shaevitz, M. H.;
Shafaq, S.; Shamma, M.; Sharankova, R.; Sharma, H. R.; Sharma, R.;
Kumar, R.; Shaw, T.; Shepherd-Themistocleous, C.; Sheshukov, A.; Shin,
S.; Shoemaker, I.; Shooltz, D.; Shrock, R.; Siegel, H.; Simard, L.;
Simon, F.; Sinclair, J.; Sinev, G.; Singh, J.; Singh, J.; Singh,
L.; Singh, V.; Sipos, R.; Sippach, F. W.; Sirri, G.; Sitraka, A.;
Siyeon, K.; Skarpaas, K.; Smith, A.; Smith, E.; Smith, P.; Smolik,
J.; Smy, M.; Snider, E. L.; Snopok, P.; Snowden-Ifft, D.; Soares
Nunes, M.; Sobel, H.; Soderberg, M.; Sokolov, S.; Solano Salinas,
C. J.; Söldner-Rembold, S.; Soleti, S. R.; Solomey, N.; Solovov,
V.; Sondheim, W. E.; Sorel, M.; Sotnikov, A.; Soto-Oton, J.; Sousa,
A.; Soustruznik, K.; Spagliardi, F.; Spanu, M.; Spitz, J.; Spooner,
N. J. C.; Spurgeon, K.; Staley, R.; Stancari, M.; Stanco, L.; Stanley,
R.; Stein, R.; Steiner, H. M.; Steklain Lisbôa, A. F.; Stewart,
J.; Stillwell, B.; Stock, J.; Stocker, F.; Stokes, T.; Strait, M.;
Strauss, T.; Striganov, S.; Stuart, A.; Suarez, J. G.; Sullivan, H.;
Summers, D.; Surdo, A.; Susic, V.; Suter, L.; Sutera, C. M.; Svoboda,
R.; Szczerbinska, B.; Szelc, A. M.; Tanaka, H. A.; Tapia Oregui, B.;
Tapper, A.; Tariq, S.; Tatar, E.; Tayloe, R.; Teklu, A. M.; Tenti,
M.; Terao, K.; Ternes, C. A.; Terranova, F.; Testera, G.; Thakore,
T.; Thea, A.; Thompson, J. L.; Thorn, C.; Timm, S. C.; Tishchenko,
V.; Todd, J.; Tomassetti, L.; Tonazzo, A.; Torbunov, D.; Torti,
M.; Tortola, M.; Tortorici, F.; Tosi, N.; Totani, D.; Toups, M.;
Touramanis, C.; Travaglini, R.; Trevor, J.; Trilov, S.; Tripathi, A.;
Trzaska, W. H.; Tsai, Y.; Tsai, Y. -T.; Tsamalaidze, Z.; Tsang, K. V.;
Tsverava, N.; Tufanli, S.; Tull, C.; Tyley, E.; Tzanov, M.; Uboldi,
L.; Uchida, M. A.; Urheim, J.; Usher, T.; Uzunyan, S.; Vagins, M. R.;
Vahle, P.; Valdiviesso, G. A.; Valencia, E.; Vallari, Z.; Vallazza,
E.; Valle, J. W. F.; Vallecorsa, S.; Van Berg, R.; Van de Water, R. G.;
Varanini, F.; Vargas, D.; Varner, G.; Vasel, J.; Vasina, S.; Vasseur,
G.; Vaughan, N.; Vaziri, K.; Ventura, S.; Verdugo, A.; Vergani, S.;
Vermeulen, M. A.; Verzocchi, M.; Vicenzi, M.; Vieira de Souza, H.;
Vignoli, C.; Vilela, C.; Viren, B.; Vrba, T.; Wachala, T.; Waldron,
A. V.; Wallbank, M.; Wallis, C.; Wang, H.; Wang, J.; Wang, L.; Wang,
M. H. L. S.; Wang, Y.; Wang, Y.; Warburton, K.; Warner, D.; Wascko,
M. O.; Waters, D.; Watson, A.; Weatherly, P.; Weber, A.; Weber, M.;
Wei, H.; Weinstein, A.; Wenman, D.; Wetstein, M.; White, A.; Whitehead,
L. H.; Whittington, D.; Wilking, M. J.; Wilkinson, C.; Williams, Z.;
Wilson, F.; Wilson, R. J.; Wisniewski, W.; Wolcott, J.; Wongjirad, T.;
Wood, A.; Wood, K.; Worcester, E.; Worcester, M.; Wret, C.; Wu, W.;
Wu, W.; Xiao, Y.; Xie, F.; Yandel, E.; Yang, G.; Yang, K.; Yang, S.;
Yang, T.; Yankelevich, A.; Yershov, N.; Yonehara, K.; Young, T.; Yu,
B.; Yu, H.; Yu, H.; Yu, J.; Yuan, W.; Zaki, R.; Zalesak, J.; Zambelli,
L.; Zamorano, B.; Zani, A.; Zazueta, L.; Zeller, G. P.; Zennamo, J.;
Zeug, K.; Zhang, C.; Zhao, M.; Zhivun, E.; Zhu, G.; Zilberman, P.;
Zimmerman, E. D.; Zito, M.; Zucchelli, S.; Zuklin, J.; Zutshi, V.;
Zwaska, R.; DUNE Collaboration
Bibcode: 2021JCAP...10..065A
Altcode:
The observation of 236 MeV muon neutrinos from kaon-decay-at-rest
(KDAR) originating in the core of the Sun would provide a unique
signature of dark matter annihilation. Since excellent angle and
energy reconstruction are necessary to detect this monoenergetic,
directional neutrino flux, DUNE with its vast volume and reconstruction
capabilities, is a promising candidate for a KDAR neutrino search. In
this work, we evaluate the proposed KDAR neutrino search strategies
by realistically modeling both neutrino-nucleus interactions and
the response of DUNE. We find that, although reconstruction of the
neutrino energy and direction is difficult with current techniques
in the relevant energy range, the superb energy resolution, angular
resolution, and particle identification offered by DUNE can still
permit great signal/background discrimination. Moreover, there are
non-standard scenarios in which searches at DUNE for KDAR in the Sun
can probe dark matter interactions.
Title: DH Type II Radio Bursts During Solar Cycles 23 and 24:
Frequency-Dependent Classification and Their Flare-CME Associations
Authors: Patel, Binal D.; Joshi, Bhuwan; Cho, Kyung-Suk; Kim, Rok-Soon
Bibcode: 2021SoPh..296..142P
Altcode: 2021arXiv210812990P
We present the characteristics of DH type II bursts for the Solar
Cycles 23 and 24. The bursts are classified according to their end
frequencies into three categories: Low-Frequency Group (LFG; 20 kHz ≤
f ≤ 200 kHz), Medium-Frequency Group (MFG; 200 kHz <f ≤1 MHz),
and High-Frequency Group (HFG; 1 MHz <f ≤16 MHz). We find that
the sources for LFG, MFG, and HFG events are homogeneously distributed
over the active region belt. Our analysis shows a drastic reduction of
the DH type II events during Solar Cycle 24, which includes only 35%
of the total events (i.e., 179 out of 514). Despite having smaller
number of DH type II events in the Solar Cycle 24, it contains a
significantly higher fraction of LFG events compared to the previous
cycle (32% versus 24%). However, within the LFG group, the cycle 23
exhibits significant dominance of type II bursts that extend below 50
kHz, suggesting rich population of powerful CMEs traveling beyond half
of the Sun-Earth distance. The events of LFG group display strongest
association with faster and wider (more than 82% events are halo)
CMEs, whereas at the source location, they predominantly trigger
large M/X class flares (in more than 83% cases). Our analysis also
indicates that CME initial speed or flare energetics is partly related
to the duration of type II burst and that survival of CME-associated
shock is determined by multiple factors/parameters related to CMEs,
flares, and state of coronal and interplanetary medium. The profiles
relating CME heights with respect to the end frequencies of DH type
II bursts suggest that for HFG and MFG categories, the location for
majority of CMEs (≈ 65%-70%) is in well compliance with ten-fold
Leblanc coronal density model, whereas for LFG events, a lower value
of density multiplier (≈ 3) seems to be compatible.
Title: Searching for solar KDAR with DUNE
Authors: DUNE Collaboration; Abed Abud, A.; Abi, B.; Acciarri, R.;
Acero, M. A.; Adames, M. R.; Adamov, G.; Adams, D.; Adinolfi, M.;
Aduszkiewicz, A.; Aguilar, J.; Ahmad, Z.; Ahmed, J.; Ali-Mohammadzadeh,
B.; Alion, T.; Allison, K.; Alonso Monsalve, S.; Alrashed, M.;
Alt, C.; Alton, A.; Amedo, P.; Anderson, J.; Andreopoulos, C.;
Andreotti, M.; Andrews, M. P.; Andrianala, F.; Andringa, S.;
Anfimov, N.; Ankowski, A.; Antoniassi, M.; Antonova, M.; Antoshkin,
A.; Antusch, S.; Aranda-Fernandez, A.; Ariga, A.; Arnold, L. O.;
Arroyave, M. A.; Asaadi, J.; Asquith, L.; Aurisano, A.; Aushev, V.;
Autiero, D.; Ayala-Torres, M.; Azfar, F.; Back, A.; Back, H.; Back,
J. J.; Backhouse, C.; Baesso, P.; Bagaturia, I.; Bagby, L.; Balashov,
N.; Balasubramanian, S.; Baldi, P.; Baller, B.; Bambah, B.; Barao,
F.; Barenboim, G.; Barker, G. J.; Barkhouse, W.; Barnes, C.; Barr,
G.; Barranco Monarca, J.; Barros, A.; Barros, N.; Barrow, J. L.;
Basharina-Freshville, A.; Bashyal, A.; Basque, V.; Belchior, E.;
Battat, J. B. R.; Battisti, F.; Bay, F.; Bazo Alba, J. L.; Beacom,
J. F.; Bechetoille, E.; Behera, B.; Bellantoni, L.; Bellettini, G.;
Bellini, V.; Beltramello, O.; Belver, D.; Benekos, N.; Benitez Montiel,
C.; Bento Neves, F.; Berger, J.; Berkman, S.; Bernardini, P.; Berner,
R. M.; Berns, H.; Bertolucci, S.; Betancourt, M.; Betancur Rodríguez,
A.; Bevan, A.; Bezerra, T. J. C.; Bhatnagar, V.; Bhattacharjee, M.;
Bhuller, S.; Bhuyan, B.; Biagi, S.; Bian, J.; Biassoni, M.; Biery, K.;
Bilki, B.; Bishai, M.; Bitadze, A.; Blake, A.; Blaszczyk, F. D. M.;
Blazey, G. C.; Blucher, E.; Boissevain, J.; Bolognesi, S.; Bolton, T.;
Bomben, L.; Bonesini, M.; Bongrand, M.; Bonini, F.; Booth, A.; Booth,
C.; Boran, F.; Bordoni, S.; Borkum, A.; Boschi, T.; Bostan, N.; Bour,
P.; Bourgeois, C.; Boyd, S. B.; Boyden, D.; Bracinik, J.; Braga,
D.; Brailsford, D.; Branca, A.; Brandt, A.; Bremer, J.; Brew, C.;
Brianne, E.; Brice, S. J.; Brizzolari, C.; Bromberg, C.; Brooijmans,
G.; Brooke, J.; Bross, A.; Brunetti, G.; Brunetti, M.; Buchanan,
N.; Budd, H.; Butorov, I.; Cagnoli, I.; Caiulo, D.; Calabrese, R.;
Calafiura, P.; Calcutt, J.; Calin, M.; Calvez, S.; Calvo, E.; Caminata,
A.; Campanelli, M.; Cankocak, K.; Caratelli, D.; Carini, G.; Carlus,
B.; Carneiro, M. F.; Carniti, P.; Caro Terrazas, I.; Carranza, H.;
Carroll, T.; Castaño Forero, J. F.; Castillo, A.; Castromonte, C.;
Catano-Mur, E.; Cattadori, C.; Cavalier, F.; Cavanna, F.; Centro,
S.; Cerati, G.; Cervelli, A.; Cervera Villanueva, A.; Chalifour,
M.; Chappell, A.; Chardonnet, E.; Charitonidis, N.; Chatterjee, A.;
Chattopadhyay, S.; Chen, H.; Chen, M.; Chen, Y.; Chen, Z.; Cheon,
Y.; Cherdack, D.; Chi, C.; Childress, S.; Chiriacescu, A.; Chisnall,
G.; Cho, K.; Choate, S.; Chokheli, D.; Chong, P. S.; Choubey, S.;
Christensen, A.; Christian, D.; Christodoulou, G.; Chukanov, A.; Chung,
M.; Church, E.; Cicero, V.; Clarke, P.; Coan, T. E.; Cocco, A. G.;
Coelho, J. A. B.; Conley, E.; Conley, R.; Conrad, J. M.; Convery,
M.; Copello, S.; Corwin, L.; Valentim, R.; Cremaldi, L.; Cremonesi,
L.; Crespo-Anadón, J. I.; Crisler, M.; Cristaldo, E.; Cross, R.;
Cudd, A.; Cuesta, C.; Cui, Y.; Cussans, D.; Dalager, O.; da Motta,
H.; Da Silva Peres, L.; David, C.; David, Q.; Davies, G. S.; Davini,
S.; Dawson, J.; De, K.; Debbins, P.; De Bonis, I.; Decowski, M. P.;
de Gouvêa, A.; De Holanda, P. C.; De Icaza Astiz, I. L.; Deisting,
A.; De Jong, P.; Delbart, A.; Delepine, D.; Delgado, M.; Dell'Acqua,
A.; De Lurgio, P.; de Mello Neto, J. R. T.; DeMuth, D. M.; Dennis, S.;
Densham, C.; Deptuch, G. W.; De Roeck, A.; De Romeri, V.; De Souza,
G.; Devi, R.; Dharmapalan, R.; Dias, M.; Diaz, F.; Díaz, J. S.;
Di Domizio, S.; Di Giulio, L.; Ding, P.; Di Noto, L.; Distefano, C.;
Diurba, R.; Diwan, M.; Djurcic, Z.; Doering, D.; Dolan, S.; Dolek,
F.; Dolinski, M. J.; Domine, L.; Douglas, D.; Douillet, D.; Drake,
G.; Drielsma, F.; Duarte, L.; Duchesneau, D.; Duffy, K.; Dunne,
P.; Durkin, T.; Duyang, H.; Dvornikov, O.; Dwyer, D. A.; Dyshkant,
A. S.; Eads, M.; Earle, A.; Edmunds, D.; Eisch, J.; Emberger, L.;
Emery, S.; Ereditato, A.; Erjavec, T.; Escobar, C. O.; Eurin, G.;
Evans, J. J.; Ewart, E.; Ezeribe, A. C.; Fahey, K.; Falcone, A.;
Fani, M.; Farnese, C.; Farzan, Y.; Fedoseev, D.; Felix, J.; Feng, Y.;
Fernandez-Martinez, E.; Fernandez Menendez, P.; Fernandez Morales,
M.; Ferraro, F.; Fields, L.; Filip, P.; Filthaut, F.; Fiorentini, A.;
Fiorini, M.; Fitzpatrick, R. S.; Flanagan, W.; Fleming, B.; Flight, R.;
Forero, D. V.; Fowler, J.; Fox, W.; Franc, J.; Francis, K.; Franco,
D.; Freeman, J.; Freestone, J.; Fried, J.; Friedland, A.; Fuentes
Robayo, F.; Fuess, S.; Furic, I. K.; Furmanski, A. P.; Gabrielli,
A.; Gago, A.; Gallagher, H.; Gallas, A.; Gallego-Ros, A.; Gallice,
N.; Galymov, V.; Gamberini, E.; Gamble, T.; Ganacim, F.; Gandhi, R.;
Gandrajula, R.; Gao, F.; Gao, S.; Garcia B., A. C.; Garcia-Gamez, D.;
García-Peris, M. Á.; Gardiner, S.; Gastler, D.; Gauvreau, J.; Ge, G.;
Gelli, B.; Gendotti, A.; Gent, S.; Ghorbani-Moghaddam, Z.; Giammaria,
P.; Giammaria, T.; Gibin, D.; Gil-Botella, I.; Gilligan, S.; Girerd,
C.; Giri, A. K.; Gnani, D.; Gogota, O.; Gold, M.; Gollapinni, S.;
Gollwitzer, K.; Gomes, R. A.; Gomez Bermeo, L. V.; Gomez Fajardo,
L. S.; Gonnella, F.; Gonzalez-Cuevas, J. A.; Gonzalez Diaz, D.;
Gonzalez-Lopez, M.; Goodman, M. C.; Goodwin, O.; Goswami, S.; Gotti,
C.; Goudzovski, E.; Grace, C.; Graham, M.; Gran, R.; Granados, E.;
Granger, P.; Grant, A.; Grant, C.; Gratieri, D.; Green, P.; Greenler,
L.; Greer, J.; Grenard, J.; Griffith, W. C.; Groh, M.; Grudzinski,
J.; Grzelak, K.; Gu, W.; Guardincerri, E.; Guarino, V.; Guarise,
M.; Guenette, R.; Guerard, E.; Guerzoni, M.; Guglielmi, A.; Guo, B.;
Guthikonda, K. K.; Gutierrez, R.; Guzowski, P.; Guzzo, M. M.; Gwon,
S.; Ha, C.; Habig, A.; Hadavand, H.; Haenni, R.; Hahn, A.; Haiston,
J.; Hamacher-Baumann, P.; Hamernik, T.; Hamilton, P.; Han, J.; Harris,
D. A.; Hartnell, J.; Harton, J.; Hasegawa, T.; Hasnip, C.; Hatcher,
R.; Hatfield, K. W.; Hatzikoutelis, A.; Hayes, C.; Hayrapetyan,
K.; Hays, J.; Hazen, E.; He, M.; Heavey, A.; Heeger, K. M.; Heise,
J.; Hennessy, K.; Henry, S.; Hernandez Morquecho, M. A.; Herner,
K.; Hertel, L.; Hewes, J.; Higuera, A.; Hill, T.; Hillier, S. J.;
Himmel, A.; Hirsch, L. R.; Ho, J.; Hoff, J.; Holin, A.; Hoppe, E.;
Horton-Smith, G. A.; Hostert, M.; Hourlier, A.; Howard, B.; Howell,
R.; Hristova, I.; Hronek, M. S.; Huang, J.; Huang, J.; Hugon, J.;
Iles, G.; Ilic, N.; Iliescu, A. M.; Illingworth, R.; Ingratta, G.;
Ioannisian, A.; Isenhower, L.; Itay, R.; Izmaylov, A.; Jackson, C. M.;
Jain, V.; James, E.; Jang, W.; Jargowsky, B.; Jediny, F.; Jena, D.;
Jeong, Y. S.; Jesús-Valls, C.; Ji, X.; Jiang, L.; Jiménez, S.; Jipa,
A.; Johnson, R.; Johnston, N.; Jones, B.; Jones, S. B.; Judah, M.;
Jung, C. K.; Junk, T.; Jwa, Y.; Kabirnezhad, M.; Kaboth, A.; Kadenko,
I.; Kakorin, I.; Kalitkina, A.; F.; Kalra, D.; Kamiya; Kaneshige, N.;
Karagiorgi, G.; Karaman, G.; Karcher, A.; Karolak, M.; Karyotakis,
Y.; Kasai, S.; Kasetti, S. P.; Kashur, L.; Kazaryan, N.; Kearns,
E.; Keener, P.; Kelly, K. J.; Kemp, E.; Kemularia, O.; Ketchum, W.;
Kettell, S. H.; Khabibullin, M.; Khotjantsev, A.; Khvedelidze, A.;
Kim, D.; King, B.; Kirby, B.; Kirby, M.; Klein, J.; Koehler, K.;
Koerner, L. W.; Kohn, S.; Koller, P. P.; Kolupaeva, L.; Korablev,
D.; Kordosky, M.; Kosc, T.; Kose, U.; Kostelecký, V. A.; Kothekar,
K.; Krennrich, F.; Kreslo, I.; Kropp, W.; Kudenko, Y.; Kudryavtsev,
V. A.; Kulagin, S.; Kumar, J.; Kumar, P.; Kunze, P.; Kuruppu, C.;
Kus, V.; Kutter, T.; Kvasnicka, J.; Kwak, D.; Lambert, A.; Land,
B. J.; Lande, K.; Lane, C. E.; Lang, K.; Langford, T.; Langstaff,
M.; Larkin, J.; Lasorak, P.; Last, D.; Lastoria, C.; Laundrie, A.;
Laurenti, G.; Lawrence, A.; Lazanu, I.; LaZur, R.; Lazzaroni, M.; Le,
T.; Leardini, S.; Learned, J.; LeBrun, P.; LeCompte, T.; Lee, C.; Lee,
S. Y.; Lehmann Miotto, G.; Lehnert, R.; Leigui de Oliveira, M. A.;
Leitner, M.; Lepin, L. M.; Li, L.; Li, S. W.; Li, T.; Li, Y.; Liao,
H.; Lin, C. S.; Lin, Q.; Lin, S.; Ling, J.; Lister, A.; Littlejohn,
B. R.; Liu, J.; Lockwitz, S.; Loew, T.; Lokajicek, M.; Lomidze, I.;
Long, K.; Loo, K.; Lord, T.; LoSecco, J. M.; Louis, W. C.; Lu, X. -G.;
Luk, K. B.; Luo, X.; Luppi, E.; Lurkin, N.; Lux, T.; Luzio, V. P.;
MacFarlane, D.; Machado, A. A.; Machado, P.; Macias, C. T.; Macier,
J. R.; Maddalena, A.; Madera, A.; Madigan, P.; Magill, S.; Mahn,
K.; Maio, A.; Major, A.; Maloney, J. A.; Mandrioli, G.; Mandujano,
R. C.; Maneira, J.; Manenti, L.; Manly, S.; Mann, A.; Manolopoulos,
K.; Manrique Plata, M.; Manyam, V. N.; Manzanillas, L.; Marchan, M.;
Marchionni, A.; Marciano, W.; Marfatia, D.; Mariani, C.; Maricic,
J.; Marie, R.; Marinho, F.; Marino, A. D.; Marsden, D.; Marshak,
M.; Marshall, C. M.; Marshall, J.; Marteau, J.; Martin-Albo, J.;
Martinez, N.; Martinez Caicedo, D. A.; Martynenko, S.; Mascagna,
V.; Mason, K.; Mastbaum, A.; Masud, M.; Matichard, F.; Matsuno, S.;
Matthews, J.; Mauger, C.; Mauri, N.; Mavrokoridis, K.; Mawby, I.;
Mazza, R.; Mazzacane, A.; Mazzucato, E.; McAskill, T.; McCluskey, E.;
McConkey, N.; McFarland, K. S.; McGrew, C.; McNab, A.; Mefodiev, A.;
Mehta, P.; Melas, P.; Mena, O.; Menary, S.; Mendez, H.; Mendez, P.;
Méndez, D. P.; Menegolli, A.; Meng, G.; Messier, M. D.; Metcalf, W.;
Mettler, T.; Mewes, M.; Meyer, H.; Miao, T.; Michna, G.; Miedema, T.;
Mikola, V.; Milincic, R.; Miller, G.; Miller, W.; Mills, J.; Milne,
C.; Mineev, O.; Miranda, O. G.; Miryala, S.; Mishra, C. S.; Mishra,
S. R.; Mislivec, A.; Mladenov, D.; Mocioiu, I.; Moffat, K.; Moggi,
N.; Mohanta, R.; Mohayai, T. A.; Mokhov, N.; Molina, J.; Molina Bueno,
L.; Montagna, E.; Montanari, A.; Montanari, C.; Montanari, D.; Montano
Zetina, L. M.; Moon, J.; Moon, S. H.; Mooney, M.; Moor, A. F.; Moreno,
D.; Morris, C.; Mossey, C.; Motuk, E.; Moura, C. A.; Mousseau, J.;
Mouster, G.; Mu, W.; Mualem, L.; Mueller, J.; Muether, M.; Mufson,
S.; Muheim, F.; Muir, A.; Mulhearn, M.; Munford, D.; Muramatsu,
H.; Murphy, S.; Musser, J.; Nachtman, J.; Nagu, S.; Nalbandyan, M.;
Nandakumar, R.; Naples, D.; Narita, S.; Nath, A.; Navas-Nicolás,
D.; Navrer-Agasson, A.; Nayak, N.; Nebot-Guinot, M.; Negishi, K.;
Nelson, J. K.; Nesbit, J.; Nessi, M.; Newbold, D.; Newcomer, M.;
Newhart, D.; Newton, H.; Nichol, R.; Nicolas-Arnaldos, F.; Niner, E.;
Nishimura, K.; Norman, A.; Norrick, A.; Northrop, R.; Novella, P.;
Nowak, J. A.; Oberling, M.; Ochoa-Ricoux, J. P.; Olivares Del Campo,
A.; Olivier, A.; Olshevskiy, A.; Onel, Y.; Onishchuk, Y.; Ott, J.;
Pagani, L.; Pakvasa, S.; Palacio, G.; Palamara, O.; Palestini, S.;
Paley, J. M.; Pallavicini, M.; Palomares, C.; Palomino-Gallo, J. L.;
Panduro Vazquez, W.; Pantic, E.; Paolone, V.; Papadimitriou, V.;
Papaleo, R.; Papanestis, A.; Paramesvaran, S.; Parke, S.; Parozzi,
E.; Parsa, Z.; Parvu, M.; Pascoli, S.; Pasqualini, L.; Pasternak,
J.; Pater, J.; Patrick, C.; Patrizii, L.; Patterson, R. B.; Patton,
S. J.; Patzak, T.; Paudel, A.; Paulos, B.; Paulucci, L.; Pavlovic,
Z.; Pawloski, G.; Payne, D.; Pec, V.; Peeters, S. J. M.; Pennacchio,
E.; Penzo, A.; Peres, O. L. G.; Perry, J.; Pershey, D.; Pessina,
G.; Petrillo, G.; Petta, C.; Petti, R.; Pia, V.; Piastra, F.;
Pickering, L.; Pietropaolo, F.; Plunkett, R.; Poling, R.; Pons, X.;
Poonthottathil, N.; Poppi, F.; Pordes, S.; Porter, J.; Potekhin,
M.; Potenza, R.; Potukuchi, B. V. K. S.; Pozimski, J.; Pozzato,
M.; Prakash, S.; Prakash, T.; Prest, M.; Prince, S.; Psihas, F.;
Pugnere, D.; Qian, X.; Queiroga Bazetto, M. C.; Raaf, J. L.; Radeka,
V.; Rademacker, J.; Radics, B.; Rafique, A.; Raguzin, E.; Rai, M.;
Rajaoalisoa, M.; Rakhno, I.; Rakotonandrasana, A.; Rakotondravohitra,
L.; Ramachers, Y. A.; Rameika, R.; Ramirez Delgado, M. A.; Ramson,
B.; Rappoldi, A.; Raselli, G.; Ratoff, P.; Raut, S.; Razakamiandra,
R. F.; Rea, E.; Real, J. S.; Rebel, B.; Reggiani-Guzzo, M.; Rehak,
T.; Reichenbacher, J.; Reitzner, S. D.; Rejeb Sfar, H.; Renshaw, A.;
Rescia, S.; Resnati, F.; Reynolds, A.; Ribas, M.; Riboldi, S.; Riccio,
C.; Riccobene, G.; Rice, L. C. J.; Ricol, J.; Rigamonti, A.; Rigaut,
Y.; Rivera, D.; Robert, A.; Rochester, L.; Roda, M.; Rodrigues, P.;
Rodriguez Alonso, M. J.; Rodriguez Bonilla, E.; Rodriguez Rondon,
J.; Rosauro-Alcaraz, S.; Rosenberg, M.; Rosier, P.; Roskovec, B.;
Rossella, M.; Rossi, M.; Rott, C.; Rout, J.; Roy, P.; Roy, S.; Rubbia,
A.; Rubbia, C.; Rubio, F. C.; Russell, B.; Ruterbories, D.; Rybnikov,
A.; Saa-Hernandez, A.; Saakyan, R.; Sacerdoti, S.; Safford, T.; Sahu,
N.; Sala, P.; Samios, N.; Samoylov, O.; Sanchez, M. C.; Sandberg,
V.; Sanders, D. A.; Sankey, D.; Santana, S.; Santos-Maldonado, M.;
Saoulidou, N.; Sapienza, P.; Sarasty, C.; Sarcevic, I.; Savage, G.;
Savinov, V.; Scaramelli, A.; Scarff, A.; Scarpelli, A.; Schaffer, T.;
Schellman, H.; Schifano, S.; Schlabach, P.; Schmitz, D.; Scholberg, K.;
Schukraft, A.; Segreto, E.; Selyunin, A.; Senise, C. R.; Sensenig, J.;
Seoane, M.; Seong, I.; Sergi, A.; Sgalaberna, D.; Shaevitz, M. H.;
Shafaq, S.; Shamma, M.; Sharankova, R.; Sharma, H. R.; Sharma, R.;
Kumar, R.; Shaw, T.; Shepherd-Themistocleous, C.; Sheshukov, A.; Shin,
S.; Shoemaker, I.; Shooltz, D.; Shrock, R.; Siegel, H.; Simard, L.;
Simon, F.; Sinclair, J.; Sinev, G.; Singh, J.; Singh, J.; Singh,
L.; Singh, V.; Sipos, R.; Sippach, F. W.; Sirri, G.; Sitraka, A.;
Siyeon, K.; Skarpaas, K.; Smith, A.; Smith, E.; Smith, P.; Smolik,
J.; Smy, M.; Snider, E. L.; Snopok, P.; Snowden-Ifft, D.; Soares
Nunes, M.; Sobel, H.; Soderberg, M.; Sokolov, S.; Solano Salinas,
C. J.; Söldner-Rembold, S.; Soleti, S. R.; Solomey, N.; Solovov,
V.; Sondheim, W. E.; Sorel, M.; Sotnikov, A.; Soto-Oton, J.; Sousa,
A.; Soustruznik, K.; Spagliardi, F.; Spanu, M.; Spitz, J.; Spooner,
N. J. C.; Spurgeon, K.; Staley, R.; Stancari, M.; Stanco, L.; Stanley,
R.; Stein, R.; Steiner, H. M.; Steklain Lisbôa, A. F.; Stewart,
J.; Stillwell, B.; Stock, J.; Stocker, F.; Stokes, T.; Strait, M.;
Strauss, T.; Striganov, S.; Stuart, A.; Suarez, J. G.; Sullivan, H.;
Summers, D.; Surdo, A.; Susic, V.; Suter, L.; Sutera, C. M.; Svoboda,
R.; Szczerbinska, B.; Szelc, A. M.; Tanaka, H. A.; Tapia Oregui, B.;
Tapper, A.; Tariq, S.; Tatar, E.; Tayloe, R.; Teklu, A. M.; Tenti,
M.; Terao, K.; Ternes, C. A.; Terranova, F.; Testera, G.; Thakore,
T.; Thea, A.; Thompson, J. L.; Thorn, C.; Timm, S. C.; Tishchenko,
V.; Todd, J.; Tomassetti, L.; Tonazzo, A.; Torbunov, D.; Torti,
M.; Tortola, M.; Tortorici, F.; Tosi, N.; Totani, D.; Toups, M.;
Touramanis, C.; Travaglini, R.; Trevor, J.; Trilov, S.; Tripathi, A.;
Trzaska, W. H.; Tsai, Y.; Tsai, Y. -T.; Tsamalaidze, Z.; Tsang, K. V.;
Tsverava, N.; Tufanli, S.; Tull, C.; Tyley, E.; Tzanov, M.; Uboldi,
L.; Uchida, M. A.; Urheim, J.; Usher, T.; Uzunyan, S.; Vagins, M. R.;
Vahle, P.; Valdiviesso, G. A.; Valencia, E.; Vallari, Z.; Vallazza,
E.; Valle, J. W. F.; Vallecorsa, S.; Van Berg, R.; Van de Water, R. G.;
Varanini, F.; Vargas, D.; Varner, G.; Vasel, J.; Vasina, S.; Vasseur,
G.; Vaughan, N.; Vaziri, K.; Ventura, S.; Verdugo, A.; Vergani, S.;
Vermeulen, M. A.; Verzocchi, M.; Vicenzi, M.; Vieira de Souza, H.;
Vignoli, C.; Vilela, C.; Viren, B.; Vrba, T.; Wachala, T.; Waldron,
A. V.; Wallbank, M.; Wallis, C.; Wang, H.; Wang, J.; Wang, L.; Wang,
M. H. L. S.; Wang, Y.; Wang, Y.; Warburton, K.; Warner, D.; Wascko,
M. O.; Waters, D.; Watson, A.; Weatherly, P.; Weber, A.; Weber, M.;
Wei, H.; Weinstein, A.; Wenman, D.; Wetstein, M.; White, A.; Whitehead,
L. H.; Whittington, D.; Wilking, M. J.; Wilkinson, C.; Williams, Z.;
Wilson, F.; Wilson, R. J.; Wisniewski, W.; Wolcott, J.; Wongjirad, T.;
Wood, A.; Wood, K.; Worcester, E.; Worcester, M.; Wret, C.; Wu, W.;
Wu, W.; Xiao, Y.; Xie, F.; Yandel, E.; Yang, G.; Yang, K.; Yang, S.;
Yang, T.; Yankelevich, A.; Yershov, N.; Yonehara, K.; Young, T.; Yu,
B.; Yu, H.; Yu, H.; Yu, J.; Yuan, W.; Zaki, R.; Zalesak, J.; Zambelli,
L.; Zamorano, B.; Zani, A.; Zazueta, L.; Zeller, G. P.; Zennamo, J.;
Zeug, K.; Zhang, C.; Zhao, M.; Zhivun, E.; Zhu, G.; Zilberman, P.;
Zimmerman, E. D.; Zito, M.; Zucchelli, S.; Zuklin, J.; Zutshi, V.;
Zwaska, R.
Bibcode: 2021arXiv210709109D
Altcode:
The observation of 236 MeV muon neutrinos from kaon-decay-at-rest
(KDAR) originating in the core of the Sun would provide a unique
signature of dark matter annihilation. Since excellent angle and
energy reconstruction are necessary to detect this monoenergetic,
directional neutrino flux, DUNE with its vast volume and reconstruction
capabilities, is a promising candidate for a KDAR neutrino search. In
this work, we evaluate the proposed KDAR neutrino search strategies
by realistically modeling both neutrino-nucleus interactions and
the response of DUNE. We find that, although reconstruction of the
neutrino energy and direction is difficult with current techniques
in the relevant energy range, the superb energy resolution, angular
resolution, and particle identification offered by DUNE can still
permit great signal/background discrimination. Moreover, there are
non-standard scenarios in which searches at DUNE for KDAR in the Sun
can probe dark matter interactions.
Title: Spectroscopic Detection of Alfvénic Waves in the Chromosphere
of Sunspot Regions
Authors: Chae, Jongchul; Cho, Kyuhyoun; Nakariakov, Valery M.; Cho,
Kyung-Suk; Kwon, Ryun-Young
Bibcode: 2021ApJ...914L..16C
Altcode:
Transverse magnetohydrodynamic waves often called Alfvénic (or
kink) waves have been often theoretically put forward to solve the
outstanding problems of the solar corona like coronal heating, solar
wind acceleration, and chemical abundance enhancement. Here we report
the first spectroscopic detection of Alfvénic waves around a sunspot at
chromospheric heights. By analyzing the spectra of the Hα line and Ca
II 854.2 nm line, we determined line-of-sight velocity and temperature
as functions of position and time. As a result, we identified transverse
magnetohydrodynamic waves pervading the superpenumbral fibrils. These
waves are characterized by the periods of 2.5 to 4.5 minutes, and
the propagation direction parallel to the fibrils, the supersonic
propagation speeds of 45 to 145 km s-1, and the close
association with umbral oscillations and running penumbral waves in
sunspots. Our results support the notion that the chromosphere around
sunspots abounds with Alfvénic waves excited by the mode conversion
of the upward-propagating slow magnetoacoustic waves.
Title: Supernova neutrino burst detection with the deep underground
neutrino experiment
Authors: Abi, B.; Acciarri, R.; Acero, M. A.; Adamov, G.; Adams, D.;
Adinolfi, M.; Ahmad, Z.; Ahmed, J.; Alion, T.; Alonso Monsalve,
S.; Alt, C.; Anderson, J.; Andreopoulos, C.; Andrews, M. P.;
Andrianala, F.; Andringa, S.; Ankowski, A.; Antonova, M.; Antusch,
S.; Aranda-Fernandez, A.; Ariga, A.; Arnold, L. O.; Arroyave, M. A.;
Asaadi, J.; Aurisano, A.; Aushev, V.; Autiero, D.; Azfar, F.; Back,
H.; Back, J. J.; Backhouse, C.; Baesso, P.; Bagby, L.; Bajou, R.;
Balasubramanian, S.; Baldi, P.; Bambah, B.; Barao, F.; Barenboim,
G.; Barker, G. J.; Barkhouse, W.; Barnes, C.; Barr, G.; Barranco
Monarca, J.; Barros, N.; Barrow, J. L.; Bashyal, A.; Basque, V.;
Bay, F.; Alba, J. L. Bazo; Beacom, J. F.; Bechetoille, E.; Behera,
B.; Bellantoni, L.; Bellettini, G.; Bellini, V.; Beltramello, O.;
Belver, D.; Benekos, N.; Bento Neves, F.; Berger, J.; Berkman, S.;
Bernardini, P.; Berner, R. M.; Berns, H.; Bertolucci, S.; Betancourt,
M.; Bezawada, Y.; Bhattacharjee, M.; Bhuyan, B.; Biagi, S.; Bian,
J.; Biassoni, M.; Biery, K.; Bilki, B.; Bishai, M.; Bitadze, A.;
Blake, A.; Blanco Siffert, B.; Blaszczyk, F. D. M.; Blazey, G. C.;
Blucher, E.; Boissevain, J.; Bolognesi, S.; Bolton, T.; Bonesini,
M.; Bongrand, M.; Bonini, F.; Booth, A.; Booth, C.; Bordoni, S.;
Borkum, A.; Boschi, T.; Bostan, N.; Bour, P.; Boyd, S. B.; Boyden,
D.; Bracinik, J.; Braga, D.; Brailsford, D.; Brandt, A.; Bremer,
J.; Brew, C.; Brianne, E.; Brice, S. J.; Brizzolari, C.; Bromberg,
C.; Brooijmans, G.; Brooke, J.; Bross, A.; Brunetti, G.; Buchanan,
N.; Budd, H.; Caiulo, D.; Calafiura, P.; Calcutt, J.; Calin, M.;
Calvez, S.; Calvo, E.; Camilleri, L.; Caminata, A.; Campanelli, M.;
Caratelli, D.; Carini, G.; Carlus, B.; Carniti, P.; Caro Terrazas,
I.; Carranza, H.; Castillo, A.; Castromonte, C.; Cattadori, C.;
Cavalier, F.; Cavanna, F.; Centro, S.; Cerati, G.; Cervelli, A.;
Cervera Villanueva, A.; Chalifour, M.; Chang, C.; Chardonnet, E.;
Chatterjee, A.; Chattopadhyay, S.; Chaves, J.; Chen, H.; Chen, M.;
Chen, Y.; Cherdack, D.; Chi, C.; Childress, S.; Chiriacescu, A.; Cho,
K.; Choubey, S.; Christensen, A.; Christian, D.; Christodoulou, G.;
Church, E.; Clarke, P.; Coan, T. E.; Cocco, A. G.; Coelho, J. A. B.;
Conley, E.; Conrad, J. M.; Convery, M.; Corwin, L.; Cotte, P.;
Cremaldi, L.; Cremonesi, L.; Crespo-Anadón, J. I.; Cristaldo, E.;
Cross, R.; Cuesta, C.; Cui, Y.; Cussans, D.; Dabrowski, M.; da Motta,
H.; Da Silva Peres, L.; David, C.; David, Q.; Davies, G. S.; Davini,
S.; Dawson, J.; De, K.; De Almeida, R. M.; Debbins, P.; De Bonis,
I.; Decowski, M. P.; de Gouvêa, A.; De Holanda, P. C.; De Icaza
Astiz, I. L.; Deisting, A.; De Jong, P.; Delbart, A.; Delepine, D.;
Delgado, M.; Dell-Acqua, A.; De Lurgio, P.; de Mello Neto, J. R. T.;
DeMuth, D. M.; Dennis, S.; Densham, C.; Deptuch, G.; De Roeck, A.;
De Romeri, V.; De Vries, J. J.; Dharmapalan, R.; Dias, M.; Diaz,
F.; Díaz, J. S.; Di Domizio, S.; Di Giulio, L.; Ding, P.; Di Noto,
L.; Distefano, C.; Diurba, R.; Diwan, M.; Djurcic, Z.; Dokania, N.;
Dolinski, M. J.; Domine, L.; Douglas, D.; Drielsma, F.; Duchesneau, D.;
Duffy, K.; Dunne, P.; Durkin, T.; Duyang, H.; Dvornikov, O.; Dwyer,
D. A.; Dyshkant, A. S.; Eads, M.; Edmunds, D.; Eisch, J.; Emery, S.;
Ereditato, A.; Escobar, C. O.; Escudero Sanchez, L.; Evans, J. J.;
Ewart, E.; Ezeribe, A. C.; Fahey, K.; Falcone, A.; Farnese, C.;
Farzan, Y.; Felix, J.; Fernandez-Martinez, E.; Fernandez Menendez,
P.; Ferraro, F.; Fields, L.; Filkins, A.; Filthaut, F.; Fitzpatrick,
R. S.; Flanagan, W.; Fleming, B.; Flight, R.; Fowler, J.; Fox, W.;
Franc, J.; Francis, K.; Franco, D.; Freeman, J.; Freestone, J.; Fried,
J.; Friedland, A.; Fuess, S.; Furic, I.; Furmanski, A. P.; Gago, A.;
Gallagher, H.; Gallego-Ros, A.; Gallice, N.; Galymov, V.; Gamberini,
E.; Gamble, T.; Gandhi, R.; Gandrajula, R.; Gao, S.; Garcia-Gamez,
D.; García-Peris, M. Á.; Gardiner, S.; Gastler, D.; Ge, G.;
Gelli, B.; Gendotti, A.; Gent, S.; Ghorbani-Moghaddam, Z.; Gibin, D.;
Gil-Botella, I.; Girerd, C.; Giri, A. K.; Gnani, D.; Gogota, O.; Gold,
M.; Gollapinni, S.; Gollwitzer, K.; Gomes, R. A.; Gomez Bermeo, L. V.;
Gomez Fajardo, L. S.; Gonnella, F.; Gonzalez-Cuevas, J. A.; Goodman,
M. C.; Goodwin, O.; Goswami, S.; Gotti, C.; Goudzovski, E.; Grace, C.;
Graham, M.; Gramellini, E.; Gran, R.; Granados, E.; Grant, A.; Grant,
C.; Gratieri, D.; Green, P.; Green, S.; Greenler, L.; Greenwood, M.;
Greer, J.; Griffith, W. C.; Groh, M.; Grudzinski, J.; Grzelak, K.; Gu,
W.; Guarino, V.; Guenette, R.; Guglielmi, A.; Guo, B.; Guthikonda,
K. K.; Gutierrez, R.; Guzowski, P.; Guzzo, M. M.; Gwon, S.; Habig,
A.; Hackenburg, A.; Hadavand, H.; Haenni, R.; Hahn, A.; Haigh, J.;
Haiston, J.; Hamernik, T.; Hamilton, P.; Han, J.; Harder, K.; Harris,
D. A.; Hartnell, J.; Hasegawa, T.; Hatcher, R.; Hazen, E.; Heavey,
A.; Heeger, K. M.; Heise, J.; Hennessy, K.; Henry, S.; Hernandez
Morquecho, M. A.; Herner, K.; Hertel, L.; Hesam, A. S.; Hewes, J.;
Higuera, A.; Hill, T.; Hillier, S. J.; Himmel, A.; Hoff, J.; Hohl,
C.; Holin, A.; Hoppe, E.; Horton-Smith, G. A.; Hostert, M.; Hourlier,
A.; Howard, B.; Howell, R.; Huang, J.; Huang, J.; Hugon, J.; Iles,
G.; Ilic, N.; Iliescu, A. M.; Illingworth, R.; Ioannisian, A.; Itay,
R.; Izmaylov, A.; James, E.; Jargowsky, B.; Jediny, F.; Jesùs-Valls,
C.; Ji, X.; Jiang, L.; Jiménez, S.; Jipa, A.; Joglekar, A.; Johnson,
C.; Johnson, R.; Jones, B.; Jones, S.; Jung, C. K.; Junk, T.; Jwa, Y.;
Kabirnezhad, M.; Kaboth, A.; Kadenko, I.; Kamiya, F.; Karagiorgi, G.;
Karcher, A.; Karolak, M.; Karyotakis, Y.; Kasai, S.; Kasetti, S. P.;
Kashur, L.; Kazaryan, N.; Kearns, E.; Keener, P.; Kelly, K. J.; Kemp,
E.; Ketchum, W.; Kettell, S. H.; Khabibullin, M.; Khotjantsev, A.;
Khvedelidze, A.; Kim, D.; King, B.; Kirby, B.; Kirby, M.; Klein, J.;
Koehler, K.; Koerner, L. W.; Kohn, S.; Koller, P. P.; Kordosky, M.;
Kosc, T.; Kose, U.; Kostelecký, V. A.; Kothekar, K.; Krennrich, F.;
Kreslo, I.; Kudenko, Y.; Kudryavtsev, V. A.; Kulagin, S.; Kumar, J.;
Kumar, R.; Kuruppu, C.; Kus, V.; Kutter, T.; Lambert, A.; Lande, K.;
Lane, C. E.; Lang, K.; Langford, T.; Lasorak, P.; Last, D.; Lastoria,
C.; Laundrie, A.; Lawrence, A.; Lazanu, I.; LaZur, R.; Le, T.; Learned,
J.; LeBrun, P.; Lehmann Miotto, G.; Lehnert, R.; Leigui de Oliveira,
M. A.; Leitner, M.; Leyton, M.; Li, L.; Li, S.; Li, S. W.; Li, T.;
Li, Y.; Liao, H.; Lin, C. S.; Lin, S.; Lister, A.; Littlejohn, B. R.;
Liu, J.; Lockwitz, S.; Loew, T.; Lokajicek, M.; Lomidze, I.; Long,
K.; Loo, K.; Lorca, D.; Lord, T.; LoSecco, J. M.; Louis, W. C.; Luk,
K. B.; Luo, X.; Lurkin, N.; Lux, T.; Luzio, V. P.; MacFarland, D.;
Machado, A. A.; Machado, P.; Macias, C. T.; Macier, J. R.; Maddalena,
A.; Madigan, P.; Magill, S.; Mahn, K.; Maio, A.; Major, A.; Maloney,
J. A.; Mandrioli, G.; Maneira, J.; Manenti, L.; Manly, S.; Mann, A.;
Manolopoulos, K.; Manrique Plata, M.; Marchionni, A.; Marciano, W.;
Marfatia, D.; Mariani, C.; Maricic, J.; Marinho, F.; Marino, A. D.;
Marshak, M.; Marshall, C.; Marshall, J.; Marteau, J.; Martin-Albo,
J.; Martinez, N.; Martinez Caicedo, D. A.; Martynenko, S.; Mason,
K.; Mastbaum, A.; Masud, M.; Matsuno, S.; Matthews, J.; Mauger, C.;
Mauri, N.; Mavrokoridis, K.; Mazza, R.; Mazzacane, A.; Mazzucato, E.;
McCluskey, E.; McConkey, N.; McFarland, K. S.; McGrew, C.; McNab, A.;
Mefodiev, A.; Mehta, P.; Melas, P.; Mellinato, M.; Mena, O.; Menary,
S.; Mendez, H.; Menegolli, A.; Meng, G.; Messier, M. D.; Metcalf, W.;
Mewes, M.; Meyer, H.; Miao, T.; Michna, G.; Miedema, T.; Migenda,
J.; Milincic, R.; Miller, W.; Mills, J.; Milne, C.; Mineev, O.;
Miranda, O. G.; Miryala, S.; Mishra, C. S.; Mishra, S. R.; Mislivec,
A.; Mladenov, D.; Mocioiu, I.; Moffat, K.; Moggi, N.; Mohanta, R.;
Mohayai, T. A.; Mokhov, N.; Molina, J.; Molina Bueno, L.; Montanari,
A.; Montanari, C.; Montanari, D.; Montano Zetina, L. M.; Moon, J.;
Mooney, M.; Moor, A.; Moreno, D.; Morgan, B.; Morris, C.; Mossey, C.;
Motuk, E.; Moura, C. A.; Mousseau, J.; Mu, W.; Mualem, L.; Mueller, J.;
Muether, M.; Mufson, S.; Muheim, F.; Muir, A.; Mulhearn, M.; Muramatsu,
H.; Murphy, S.; Musser, J.; Nachtman, J.; Nagu, S.; Nalbandyan, M.;
Nandakumar, R.; Naples, D.; Narita, S.; Navas-Nicolás, D.; Nayak, N.;
Nebot-Guinot, M.; Necib, L.; Negishi, K.; Nelson, J. K.; Nesbit, J.;
Nessi, M.; Newbold, D.; Newcomer, M.; Newhart, D.; Nichol, R.; Niner,
E.; Nishimura, K.; Norman, A.; Norrick, A.; Northrop, R.; Novella,
P.; Nowak, J. A.; Oberling, M.; Olivares Del Campo, A.; Olivier, A.;
Onel, Y.; Onishchuk, Y.; Ott, J.; Pagani, L.; Pakvasa, S.; Palamara,
O.; Palestini, S.; Paley, J. M.; Pallavicini, M.; Palomares, C.;
Pantic, E.; Paolone, V.; Papadimitriou, V.; Papaleo, R.; Papanestis,
A.; Paramesvaran, S.; Parke, S.; Parsa, Z.; Parvu, M.; Pascoli, S.;
Pasqualini, L.; Pasternak, J.; Pater, J.; Patrick, C.; Patrizii, L.;
Patterson, R. B.; Patton, S. J.; Patzak, T.; Paudel, A.; Paulos,
B.; Paulucci, L.; Pavlovic, Z.; Pawloski, G.; Payne, D.; Pec, V.;
Peeters, S. J. M.; Penichot, Y.; Pennacchio, E.; Penzo, A.; Peres,
O. L. G.; Perry, J.; Pershey, D.; Pessina, G.; Petrillo, G.; Petta,
C.; Petti, R.; Piastra, F.; Pickering, L.; Pietropaolo, F.; Pillow,
J.; Pinzino, J.; Plunkett, R.; Poling, R.; Pons, X.; Poonthottathil,
N.; Pordes, S.; Potekhin, M.; Potenza, R.; Potukuchi, B. V. K. S.;
Pozimski, J.; Pozzato, M.; Prakash, S.; Prakash, T.; Prince, S.;
Prior, G.; Pugnere, D.; Qi, K.; Qian, X.; Raaf, J. L.; Raboanary,
R.; Radeka, V.; Rademacker, J.; Radics, B.; Rafique, A.; Raguzin,
E.; Rai, M.; Rajaoalisoa, M.; Rakhno, I.; Rakotondramanana, H. T.;
Rakotondravohitra, L.; Ramachers, Y. A.; Rameika, R.; Ramirez Delgado,
M. A.; Ramson, B.; Rappoldi, A.; Raselli, G.; Ratoff, P.; Ravat, S.;
Razafinime, H.; Real, J. S.; Rebel, B.; Redondo, D.; Reggiani-Guzzo,
M.; Rehak, T.; Reichenbacher, J.; Reitzner, S. D.; Renshaw, A.; Rescia,
S.; Resnati, F.; Reynolds, A.; Riccobene, G.; Rice, L. C. J.; Rielage,
K.; Rigaut, Y.; Rivera, D.; Rochester, L.; Roda, M.; Rodrigues, P.;
Rodriguez Alonso, M. J.; Rodriguez Rondon, J.; Roeth, A. J.; Rogers,
H.; Rosauro-Alcaraz, S.; Rossella, M.; Rout, J.; Roy, S.; Rubbia, A.;
Rubbia, C.; Russell, B.; Russell, J.; Ruterbories, D.; Saakyan, R.;
Sacerdoti, S.; Safford, T.; Sahu, N.; Sala, P.; Samios, N.; Sanchez,
M. C.; Sanders, D. A.; Sankey, D.; Santana, S.; Santos-Maldonado, M.;
Saoulidou, N.; Sapienza, P.; Sarasty, C.; Sarcevic, I.; Savage, G.;
Savinov, V.; Scaramelli, A.; Scarff, A.; Scarpelli, A.; Schaffer, T.;
Schellman, H.; Schlabach, P.; Schmitz, D.; Scholberg, K.; Schukraft,
A.; Segreto, E.; Sensenig, J.; Seong, I.; Sergi, A.; Sergiampietri,
F.; Sgalaberna, D.; Shaevitz, M. H.; Shafaq, S.; Shamma, M.; Sharma,
H. R.; Sharma, R.; Shaw, T.; Shepherd-Themistocleous, C.; Shin, S.;
Shooltz, D.; Shrock, R.; Simard, L.; Simos, N.; Sinclair, J.; Sinev,
G.; Singh, J.; Singh, J.; Singh, V.; Sipos, R.; Sippach, F. W.; Sirri,
G.; Sitraka, A.; Siyeon, K.; Smargianaki, D.; Smith, A.; Smith,
E.; Smith, P.; Smolik, J.; Smy, M.; Snopok, P.; Soares Nunes, M.;
Sobel, H.; Soderberg, M.; Solano Salinas, C. J.; Söldner-Rembold,
S.; Solomey, N.; Solovov, V.; Sondheim, W. E.; Sorel, M.; Soto-Oton,
J.; Sousa, A.; Soustruznik, K.; Spagliardi, F.; Spanu, M.; Spitz, J.;
Spooner, N. J. C.; Spurgeon, K.; Staley, R.; Stancari, M.; Stanco,
L.; Steiner, H. M.; Stewart, J.; Stillwell, B.; Stock, J.; Stocker,
F.; Stokes, T.; Strait, M.; Strauss, T.; Striganov, S.; Stuart, A.;
Summers, D.; Surdo, A.; Susic, V.; Suter, L.; Sutera, C. M.; Svoboda,
R.; Szczerbinska, B.; Szelc, A. M.; Talaga, R.; Tanaka, H. A.; Tapia
Oregui, B.; Tapper, A.; Tariq, S.; Tatar, E.; Tayloe, R.; Teklu, A. M.;
Tenti, M.; Terao, K.; Ternes, C. A.; Terranova, F.; Testera, G.; Thea,
A.; Thompson, J. L.; Thorn, C.; Timm, S. C.; Tonazzo, A.; Torti, M.;
Tórtola, M.; Tortorici, F.; Totani, D.; Toups, M.; Touramanis, C.;
Trevor, J.; Trzaska, W. H.; Tsai, Y. T.; Tsamalaidze, Z.; Tsang, K. V.;
Tsverava, N.; Tufanli, S.; Tull, C.; Tyley, E.; Tzanov, M.; Uchida,
M. A.; Urheim, J.; Usher, T.; Vagins, M. R.; Vahle, P.; Valdiviesso,
G. A.; Valencia, E.; Vallari, Z.; Valle, J. W. F.; Vallecorsa, S.;
Van Berg, R.; Van de Water, R. G.; Vanegas Forero, D.; Varanini,
F.; Vargas, D.; Varner, G.; Vasel, J.; Vasseur, G.; Vaziri, K.;
Ventura, S.; Verdugo, A.; Vergani, S.; Vermeulen, M. A.; Verzocchi,
M.; Vieira de Souza, H.; Vignoli, C.; Vilela, C.; Viren, B.; Vrba,
T.; Wachala, T.; Waldron, A. V.; Wallbank, M.; Wang, H.; Wang, J.;
Wang, Y.; Wang, Y.; Warburton, K.; Warner, D.; Wascko, M.; Waters, D.;
Watson, A.; Weatherly, P.; Weber, A.; Weber, M.; Wei, H.; Weinstein,
A.; Wenman, D.; Wetstein, M.; While, M. R.; White, A.; Whitehead,
L. H.; Whittington, D.; Wilking, M. J.; Wilkinson, C.; Williams, Z.;
Wilson, F.; Wilson, R. J.; Wolcott, J.; Wongjirad, T.; Wood, K.; Wood,
L.; Worcester, E.; Worcester, M.; Wret, C.; Wu, W.; Wu, W.; Xiao,
Y.; Yang, G.; Yang, T.; Yershov, N.; Yonehara, K.; Young, T.; Yu, B.;
Yu, J.; Zaki, R.; Zalesak, J.; Zambelli, L.; Zamorano, B.; Zani, A.;
Zazueta, L.; Zeller, G. P.; Zennamo, J.; Zeug, K.; Zhang, C.; Zhao,
M.; Zhivun, E.; Zhu, G.; Zimmerman, E. D.; Zito, M.; Zucchelli, S.;
Zuklin, J.; Zutshi, V.; Zwaska, R.
Bibcode: 2021EPJC...81..423A
Altcode: 2020arXiv200806647D; 2020arXiv200806647A
The deep underground neutrino experiment (DUNE), a 40-kton underground
liquid argon time projection chamber experiment, will be sensitive
to the electron-neutrino flavor component of the burst of neutrinos
expected from the next Galactic core-collapse supernova. Such an
observation will bring unique insight into the astrophysics of core
collapse as well as into the properties of neutrinos. The general
capabilities of DUNE for neutrino detection in the relevant few- to
few-tens-of-MeV neutrino energy range will be described. As an example,
DUNE's ability to constrain the νe spectral parameters of
the neutrino burst will be considered.
Title: Space missions for astronomy and astrophysics in Korea: past,
present, and future
Authors: Seon, Kwang-Il; Han, Wonyong; Lee, Young-Wook; Lee, Hyung
Mok; Kim, Min Bin; Park, I. H.; Jeong, Woong-Seob; Cho, Kyung-Suk;
Lee, Jae Jin; Lee, Dae-Hee; Kwak, Kyujin
Bibcode: 2021JKPS...78..942S
Altcode: 2021JKPS..tmp..132S; 2020arXiv201201120S
We review the history of space missions in Korea focusing on the field
of astronomy and astrophysics. For each mission, scientific motivation
and achievement are reviewed together with some technical details of
the program, including mission schedule. This review includes ongoing
and currently approved missions, as well as some planned ones. Within
the admitted limitations of the authors' perspectives, some comments on
the future direction of the space program for astronomy and astrophysics
in Korea are made at the end of this review.
Title: Comparison of LOS Doppler Velocities and Non-thermal Line
Widths in the Off-limb Solar Corona Measured Simultaneously by CoMP
and Ninode/EIS
Authors: Lee, Jae-Ok; Lee, Kyoung-Sun; Seough, Jungjoon; Cho, Kyung-Suk
Bibcode: 2021JKAS...54...49L
Altcode:
Observations of line of sight (LOS) Doppler velocity and non-thermal
line width in the off-limb solar corona are often used for investigating
the Alfvén wave signatures in the corona. In this study, we compare LOS
Doppler velocities and non-thermal line widths obtained simultaneously
from two different instruments, Coronal Multichannel Polarimeter (CoMP)
and Hinode/EUV Imaging Spectrometer (EIS), on various off-limb coronal
regions: flaring and quiescent active regions, equatorial quiet region,
and polar prominence and plume regions observed in 2012-2014. CoMP
provides the polarization at the Fe XIII 10747 Å coronal forbidden
lines which allows their spectral line intensity, LOS Doppler velocity,
and line width to be measured with a low spectral resolution of 1.2 Å
in 2-D off limb corona between 1.05 and 1.40 R_Sun, while Hinode/EIS
gives us the EUV spectral information with a high spectral resolution
(0.025 Å) in a limited field of view raster scan. In order to compare
them, we make pseudo raster scan CoMP maps using information
of each EIS scan slit time and position. We compare the CoMP and EIS
spectroscopic maps by visual inspection, and examine their pixel to
pixel correlations and percentages of pixel numbers satisfying the
condition that the differences between CoMP and EIS spectroscopic
quantities are within the EIS measurement accuracy: ±3 km/s for
LOS Doppler velocity and ±9 km/s for non-thermal width. The main
results are summarized as follows. By comparing CoMP and EIS Doppler
velocity distributions, we find that they are consistent with each
other overall in the active regions and equatorial quiet region (0.25
≤ CC ≤ 0.7), while they are partially similar to each other in
the overlying loops of prominences and near the bottom of the polar
plume (0.02 ≤ CC ≤ 0.18). CoMP Doppler velocities are consistent
with the EIS ones within the EIS measurement accuracy in most regions
(≥ 87% of pixels) except for the polar region (45% of pixels). We
find that CoMP and EIS non-thermal width distributions are similar
overall in the active regions (0.06 ≤ CC ≤ 0.61), while they seem
to be different in the others (-0.1 ≤ CC ≤ 0.00). CoMP non-thermal
widths are similar to EIS ones within the EIS measurement accuracy
in a quiescent active region (79% of pixels), while they do not match
in the other regions (≤ 61% of pixels); the CoMP observations tend
to underestimate the widths by about 20% to 40% compared to the EIS
ones. Our results demonstrate that CoMP observations can provide
reliable 2-D LOS Doppler velocity distributions on active regions and
might provide their non-thermal width distributions.
Title: Kinematic Oscillations of Post-CME Blobs Detected by K-Cor
on 2017 September 10
Authors: Lee, Jae-Ok; Cho, Kyung-Suk; Nakariakov, Valery M.; Lee,
Harim; Kim, Rok-Soon; Jang, Soojeong; Yang, Heesu; Kim, Sujin; Kim,
Yeon-Han
Bibcode: 2021JKAS...54...61L
Altcode:
We investigate 20 post-coronal mass ejection (CME) blobs formed in
the post-CME current sheet (CS) that were observed by K-Cor on 2017
September 10. By visual inspection of the trajectories and projected
speed variations of each blob, we find that all blobs except one
show irregular "zigzag" trajectories resembling transverse oscillatory
motions along the CS, and have at least one oscillatory pattern in their
instantaneous radial speeds. Their oscillation periods are ranging from
30 to 91 s and their speed amplitudes from 128 to 902 km/s. Among 19
blobs, 10 blobs have experienced at least two cycles of radial speed
oscillations with different speed amplitudes and periods, while 9 blobs
undergo one oscillation cycle. To examine whether or not the apparent
speed oscillations can be explained by vortex shedding, we estimate
the quantitative parameter of vortex shedding, the Strouhal number,
by using the observed lateral widths, linear speeds, and oscillation
periods of the blobs. We then compare our estimates with theoretical
and experimental results from MHD simulations and fluid dynamics
experiments. We find that the observed Strouhal numbers range from 0.2
to 2.1, consistent with those (0.15-3.0) from fluid dynamics experiments
of bluff spheres, while they are higher than those (0.15-0.25) from MHD
simulations of cylindrical shapes. We thus find that blobs formed in
a post-CME CS undergo kinematic oscillations caused by fluid dynamic
vortex shedding. The vortex shedding is driven by the interaction
of the outward-moving blob having a bluff spherical shape with the
background plasma in the post-CME CS.
Title: On the Nature of Propagating Intensity Disturbances in Polar
Plumes during the 2017 Total Solar Eclipse
Authors: Cho, Kyung-Suk; Cho, Il-Hyun; Madjarska, Maria S.; Nakariakov,
Valery M.; Yang, Heesu; Choi, Seonghwan; Lim, Eun-Kyung; Lee,
Kyung-Sun; Seough, Jung-Jun; Lee, Jaeok; Kim, Yeon-Han
Bibcode: 2021ApJ...909..202C
Altcode: 2021arXiv210202085C
The propagating intensity disturbances (PIDs) in plumes are still
poorly understood, and their identity (magnetoacoustic waves or flows)
remains an open question. We investigate PIDs in five plumes located
in the northern polar coronal hole observed during the 2017 total solar
eclipse. Three plumes are associated with coronal bright points, jets,
and macrospicules at their base (active plumes), and the other two
plumes are not (quiet plumes). The electron temperature at the base of
the plumes is obtained from the filter ratio of images taken with the
X-ray Telescope on board Hinode and the passband ratio around 400 nm
from an eclipse instrument, the Diagnostic Coronagraph Experiment. The
phase speed (vr), frequency (ω), and wavenumber (k) of the
PIDs in the plumes are obtained by applying a Fourier transformation to
the spacetime (r - t plane) plots in images taken with the Atmospheric
Imaging Assembly (AIA) in three different wavelength channels (171,
193, and 211 Å). We found that the PIDs in the higher-temperature AIA
channels, 193 and 211 Å, are faster than that of the cooler AIA 171
Å channel. This tendency is more significant for the active plumes
than the quiet ones. The observed speed ratio (∼1.3) between the
AIA 171 and 193 Å channels is similar to the theoretical value (1.25)
of a slow magnetoacoustic wave. Our results support the idea that PIDs
in plumes represent a superposition of slow magnetoacoustic waves and
plasma outflows that consist of dense cool flows and hot coronal jets.
Title: The Balloon-Borne Investigation of Temperature and Speed of
Electrons in the Corona (BITSE): Mission Description and Preliminary
Results
Authors: Gopalswamy, N.; Newmark, J.; Yashiro, S.; Mäkelä, P.;
Reginald, N.; Thakur, N.; Gong, Q.; Kim, Y. -H.; Cho, K. -S.; Choi,
S. -H.; Baek, J. -H.; Bong, S. -C.; Yang, H. -S.; Park, J. -Y.; Kim,
J. -H.; Park, Y. -D.; Lee, J. -O.; Kim, R. -S.; Lim, E. -K.
Bibcode: 2021SoPh..296...15G
Altcode: 2020arXiv201106111G
We report on the Balloon-borne Investigation of Temperature and Speed of
Electrons in the corona (BITSE) mission launched recently to observe the
solar corona from ≈3 Rs to 15 Rs at four wavelengths (393.5, 405.0,
398.7, and 423.4 nm). The BITSE instrument is an externally occulted
single stage coronagraph developed at NASA's Goddard Space Flight Center
in collaboration with the Korea Astronomy and Space Science Institute
(KASI). BITSE used a polarization camera that provided polarization
and total brightness images of size 1024 ×1024 pixels. The Wallops
Arc Second Pointer (WASP) system developed at NASA's Wallops Flight
Facility (WFF) was used for Sun pointing. The coronagraph and WASP were
mounted on a gondola provided by WFF and launched from the Fort Sumner,
New Mexico station of Columbia Scientific Balloon Facility (CSBF) on
September 18, 2019. BITSE obtained 17,060 coronal images at a float
altitude of ≈128,000 feet (≈39 km) over a period of ≈4 hrs. BITSE
flight software was based on NASA's core Flight System, which was
designed to help develop flight quality software. We used EVTM (Ethernet
Via Telemetry) to download science data during operations; all images
were stored on board using flash storage. At the end of the mission,
all data were recovered and analyzed. Preliminary analysis shows that
BITSE imaged the solar minimum corona with the equatorial streamers
on the east and west limbs. The narrow streamers observed by BITSE are
in good agreement with the geometric properties obtained by the Solar
and Heliospheric Observatory (SOHO) coronagraphs in the overlapping
physical domain. In spite of the small signal-to-noise ratio (≈14 )
we were able to obtain the temperature and flow speed of the western
steamer. In the heliocentric distance range 4 - 7 Rs on the western
streamer, we obtained a temperature of ≈1.0 ±0.3 MK and a flow
speed of ≈260 km s−1 with a large uncertainty interval.
Title: Understanding Formative Winds of Intracrater Aeolian Dunes
on Mars
Authors: Cho, K.; Gunn, A.; Jerolmack, D. J.
Bibcode: 2020AGUFMEP0180005C
Altcode:
The modern Martian landscape is primarily dominated by aeolian
processes, with dune migrations and sand fluxes comparable to
terrestrial values. Despite the significantly lower atmospheric
density, many of the same Earth-wind processes and transport laws
still apply. Mars is also punctuated with thousands of craters,
many containing active dune fields, ripples, and other aeolian
landforms. Wind patterns and sediment supply within these craters
determine the shape, size, and migration patterns of these dunes. Here
we study the end-member atmospheric phenomena that produce these
intracrater dunes: katabatic and convective winds. Both are caused by
the daily heating and cooling of the near-surface atmosphere, with
the former produced by nocturnal gravity flows along crater walls,
and the latter by extreme free convection in the afternoon allowing
geostrophic momentum transfer to the dunes. Dune orientations collected
from NASA's High Resolution Imaging Experiment (HiRISE), which serve as
proxies for local wind direction, are compared to slope flow directions
inferred from the Mars Orbiter Laser Altimeter (MOLA) and simulated
large-scale regional wind directions from the Mars Climate Database
(MCD). We find no clear global preferential alignment towards either
local slope flows, or non-local climate wind. We develop a simple theory
for katabatic flow and the impact threshold of sediment transport,
and use it to examine the propensity for katabatic vs. climatic flows
to move sand. This theory reveals the relative importance of each in
terms of their contribution to dune orientations on Mars. We find that
latitude and seasonality play important roles in forming the aeolian
dunes that inhabit Martian craters.
Title: The Coronal Diagnostic Experiment (CODEX)
Authors: Newmark, J. S.; Gopalswamy, N.; Kim, Y. H.; Viall, N. M.;
Cho, K. S. F.; Reginald, N. L.; Bong, S. C.; Gong, Q.; Choi, S.;
Strachan, L.; Yashiro, S.
Bibcode: 2020AGUFMSH0280011N
Altcode:
Understanding solar wind sources and acceleration mechanisms
is an overarching solar physics goal. Current models are highly
under-constrained due to the limitations of the existing data,
particularly in the ~3-10 Rs range. COronal Diagnostic EXperiment
(CODEX) is designed to deliver the first global, comprehensive
data sets that will impose crucial constraints and answer targeted
essential questions, including: Are there signatures of hot plasma
released into the solar wind from previously closed fields? What are
the velocities and temperatures of the density structures that are
observed so ubiquitously within streamers and coronal holes? To
provide these crucial measurements, NASA's Goddard Space Flight Center,
in collaboration with the Korea Astronomy and Space Science Institute,
will develop a next-generation coronagraph for the International
Space Station. This imaging coronagraph uses multiple filters to obtain
simultaneous measurements of electron density, temperature, and velocity
within a single instrument. This will be the first time all three
have been measured simultaneously for this critical field-of-view,
and CODEX achieves these measurements multiple times a day.
Title: Accelerating and Supersonic Density Disturbances in Solar
Polar Plumes
Authors: Cho, I. H.; Moon, Y. J.; Nakariakov, V. M.; Lee, J. Y.; Yu,
D. J.; Cho, K. S. F.; Yurchyshyn, V.; Lee, H.
Bibcode: 2020AGUFMSH0290003C
Altcode:
Propagating intensity disturbances in solar coronal holes are often
considered as wave propagations or mass flows. By applying the
differential emission measure technique for the extreme ultraviolet
images taken by the Atmospheric Imaging Assembly on board the Solar
Dynamics Observatory, we analyze the propagation speed of density
disturbances of plume structure in an off-limb coronal hole for a
given temperature. We construct the map of cross-correlation between
density profile for a given height and the profile at the height
of 50 Mm. The evolution of density disturbances is well fitted by
the second-order polynomial. The acceleration is calculated to be
36 m s-2. The initial speed is 134 km s-1
which is comparable with the sound speed given by the DEM-weighted
temperature. Hence, density disturbances are accelerating and supersonic
at around the base of the solar corona. The excess speed relative
to the sound speed is ∼ 30 km s-1 at the height of 1.23
solar radii, which is consistent with the Doppler speeds and Doppler
dimming speeds observed by different instruments. The extrapolated
sonic distance of the excess speed is ∼ 2.16 solar radii which is
consistent with those of solar winds. The lower limit of the mass
flux corresponds to 7% of the global solar wind. Hence, we interpret
that the observed density disturbances are slow magnetoacoustic waves
propagating in subsonic and accelerating solar winds.
Title: Accelerating and Supersonic Density Fluctuations in Coronal
Hole Plumes: Signature of Nascent Solar Winds
Authors: Cho, Il-Hyun; Nakariakov, Valery M.; Moon, Yong-Jae; Lee,
Jin-Yi; Yu, Dae Jung; Cho, Kyung-Suk; Yurchyshyn, Vasyl; Lee, Harim
Bibcode: 2020ApJ...900L..19C
Altcode: 2020arXiv200807848C
Slow magnetoacoustic waves in a static background provide a
seismological tool to probe the solar atmosphere in the analytic
frame. By analyzing the spatiotemporal variation of the electron
number density of plume structure in coronal holes above the limb for
a given temperature, we find that the density perturbations accelerate
with supersonic speeds in the distance range from 1.02 to 1.23 solar
radii. We interpret them as slow magnetoacoustic waves propagating at
about the sound speed with accelerating subsonic flows. The average
sonic height of the subsonic flows is calculated to be 1.27 solar
radii. The mass flux of the subsonic flows is estimated to be 44.1%
relative to the global solar wind. Hence, the subsonic flow is likely
to be the nascent solar wind. In other words, the evolution of the
nascent solar wind in plumes at the low corona is quantified for the
first time from imaging observations. Based on the interpretation,
propagating density perturbations present in plumes could be used as
a seismological probe of the gradually accelerating solar wind.
Title: Toward a Next Generation Solar Coronagraph: Diagnostic
Coronagraph Experiment
Authors: Cho, Kyung-Suk; Yang, Heesu; Lee, Jae-Ok; Bong, Su-Chan;
Kim, Jihun; Choi, Seonghwan; Park, Jongyeob; Cho, Kyuhoun; Baek,
Ji-Hye; Kim, Yeon-Han; Park, Young-Deuk
Bibcode: 2020JKAS...53...87C
Altcode: 2020arXiv200606155C
The Korea Astronomy and Space Science Institute (KASI) has been
developing a next-generation coronagraph (NGC) in cooperation with
NASA to measure the coronal electron density, temperature, and
speed simultaneously, using four different optical filters around
400 nm. KASI organized an expedition to demonstrate the coronagraph
measurement scheme and the instrumental technology during the 2017
total solar eclipse (TSE) across the USA. The observation site was in
Jackson Hole, Wyoming, USA. We built an eclipse observation system,
the Diagnostic Coronal Experiment (DICE), composed of two identical
telescopes to improve the signal-to-noise ratio. The observation
was conducted at four wavelengths and three linear polarization
directions in the limited total eclipse time of about 140 seconds. We
successfully obtained polarization data for the corona but we were
not able to obtain information on the coronal electron temperature
and speed due to the low signal-to-noise ratio of the optical system
and strong emission from prominences located at the western limb. In
this study, we report the development of DICE and the observation
results from the eclipse expedition. TSE observation and analysis
with our self-developed instrument showed that a coronagraph needs
to be designed carefully to achieve its scientific purpose. We gained
valuable experience for future follow-up NASA-KASI joint missions: the
Balloon-borne Investigation of the Temperature and Speed of Electrons
in the Corona (BITSE) and the COronal Diagnostic EXperiment (CODEX).
Title: The Application of the Filtered Backprojection Algorithm to
Solar Rotational Tomography
Authors: Cho, Kyuhyoun; Chae, Jongchul; Kwon, Ryun-Young; Bong,
Su-Chan; Cho, Kyung-Suk
Bibcode: 2020ApJ...895...55C
Altcode: 2020arXiv200506388C
Solar rotational tomography (SRT) is an important method to reconstruct
the physical parameters of the three-dimensional solar corona. Here
we propose an approach to apply the filtered backprojection (FBP)
algorithm to the SRT. The FBP algorithm is generally not suitable
for SRT due to the several issues with solar extreme ultraviolet
(EUV) observations—in particular, a problem caused by missing data
because of the unobserved back side of corona hidden behind the Sun. We
developed a method to generate a modified sinogram that resolves the
blocking problem. The modified sinogram is generated by combining
the EUV data at two opposite sites observed by the Atmospheric
Imaging Assembly on board the Solar Dynamics Observatory (SDO). We
generated the modified sinogram for about one month in 2019 February
and reconstructed the three-dimensional corona under the static state
assumption. In order to obtain the physical parameters of the corona,
we employed a differential emission measure inversion method. We
tested the performance of the FBP algorithm with the modified sinogram
by comparing the reconstructed data with the observed EUV image,
electron density models, previous studies of electron temperature,
and an observed coronagraph image. The results illustrate that the FBP
algorithm reasonably reconstructs the bright regions and the coronal
holes and can reproduce their physical parameters. The main advantage of
the FBP algorithm is that it is easy to understand and computationally
efficient. Thus, it enables us to easily probe the inhomogeneous coronal
electron density and temperature distribution of the solar corona.
Title: Formation of Post-CME Blobs Observed by LASCO-C2 and K-Cor
on 2017 September 10
Authors: Lee, Jae-Ok; Cho, Kyung-Suk; Lee, Kyoung-Sun; Cho, Il-Hyun;
Lee, Junggi; Miyashita, Yukinaga; Kim, Yeon-Han; Kim, Rok-Soon;
Jang, Soojeong
Bibcode: 2020ApJ...892..129L
Altcode:
Understanding the formation of post-CME blobs, we investigate 2 blobs
in the outer corona observed by LASCO-C2 and 34 blobs in the inner
corona by K-Cor on 2017 September 10 from 17:11 to 18:58 UT. By visual
inspection of the structure of a post-CME current sheet (CS) and its
associated blobs, we find that the CS is well identified in the K-Cor
and its radial lengths are nine times longer than lateral widths,
indicating the CS is unstable to the linear tearing mode. The inner
corona blobs can be classified into two groups: 27 blobs generated in
the middle of the CS (Group 1) and 7 blobs occurred above the tips of it
(Group 2). Their lateral widths are < 0.02 R⊙ > and
< 0.05 R⊙>, which is smaller than, or similar to,
those (< 0.06 R⊙ >) of the CS. They have elongated
shapes: ratios of lateral to radial widths are < 0.53 > and <
0.40 >, respectively. In the first group, only three blobs propagate
above the tip of the CS while the others are located in the CS. In the
second group, only two blobs have associations with those of outer
corona in their temporal and spatial relationship and their initial
heights are 1.81 and 1.95 R⊙, measured from the center
of the Sun. The others cannot be identified in the outer corona. Our
results first demonstrate that LASCO-C2 blobs could be generated by the
tearing mode instability near the tips of post-CME CSs, similar to the
magnetic reconnection process in the tail CS of Earth's magnetosphere.
Title: Rapid Evolution of Type II Spicules Observed in Goode Solar
Telescope On-disk Hα Images
Authors: Yurchyshyn, Vasyl; Cao, Wenda; Abramenko, Valentina; Yang,
Xu; Cho, Kyung-Suk
Bibcode: 2020ApJ...891L..21Y
Altcode: 2020arXiv200504253Y
We analyze ground-based chromospheric data acquired at a high temporal
cadence of 2 s in wings of the Hα spectral line using the
Goode Solar Telescope operating at the Big Bear Solar Observatory. We
inspected a 30 minute long Hα-0.08 nm data set to find
that rapid blueshifted Hα excursions (RBEs), which are a
cool component of type II spicules, experience very rapid morphological
changes on timescales of the order of 1 s. Unlike typical reconnection
jets, RBEs very frequently appear in situ without any clear evidence
of Hα material being injected from below. Their evolution
includes inverted "Y," "V," "N," and parallel splitting (doubling)
patterns as well as sudden formation of a diffuse region followed
by branching. We also find that the same feature may undergo several
splitting episodes within about a 1 minute time interval.
Title: Oscillation of a Small Hα Surge in a Solar Polar Coronal Hole
Authors: Cho, K. S. F.
Bibcode: 2019AGUFMSH53B3375C
Altcode:
Hα surges (i.e., cool/dense collimated plasma ejections) may act as
a guide for a propagation of magnetohydrodynamic waves. We report
a high-resolution observation of a surge observed with 1.6 m Goode
Solar Telescope (GST) on 2009 August 26, from 18:20 UT to 18:45
UT. Characteristics of plasma motions in the surge are determined
with the normalizing radial gradient filter and the Fourier motion
filter. The shape of the surge is found to change from a "C" shape
to an inverse "C" shape after a formation of a cusp, a signature of
reconnection. There are apparent upflows seen above the cusp top and
downflows below it. The upflows show rising and rotational motions
in the right-hand direction, with the rotational speed decreasing
with height. Near the cusp top, we find a transverse oscillation
of the surge, with the period of ∼2 minutes. There is no change
of the oscillation phase below the cusp top, but above the top a
phase change is identified, giving a vertical phase speed about 86 km
s-1. As the height increases, the initial amplitude of the
oscillation increases, and the oscillation damping time decreases
from 5.13 to 1.18 minutes. We conclude that the oscillation is a
propagating kink wave that is possibly excited by the repetitive
spontaneous magnetic reconnection.
Title: Visualizing Seasons and Moon Phases with WorldWide Telescope
Authors: Udomprasert, P.; Houghton, H.; Sunbury, S.; Plummer, J.;
Wright, E.; Goodman, A.; Johnson, E.; Zhang, H.; Vaishampayan, A.;
Cho, K.
Bibcode: 2019ASPC..524..125U
Altcode:
WorldWide Telescope (WWT) is a powerful visualization program that
allows users to connect Earth-based and space-based views of the
Sun-Earth-Moon system. By blending hands-on physical activities with
WWT's virtual models, students can visualize spatially complex concepts
like seasons, Moon phases, and eclipses. In this workshop, we will
demonstrate how WWT and the physical models are used together in our
WWT ThinkSpace curriculum, developed with funding from the National
Science Foundation. We will also present student learning outcomes
based on written assessments and student interviews.
Title: A New Type of Jet in a Polar Limb of the Solar Coronal Hole
Authors: Cho, Il-Hyun; Moon, Yong-Jae; Cho, Kyung-Suk; Nakariakov,
Valery M.; Lee, Jin-Yi; Kim, Yeon-Han
Bibcode: 2019ApJ...884L..38C
Altcode: 2019arXiv191009737C
A new type of chromospheric jet in a polar limb of a coronal hole is
discovered in the Ca II filtergram of the Solar Optical Telescope on
board the Hinode. We identify 30 jets in a filtered Ca II movie with
a duration of 53 minutes. The average speed at their maximum heights
is found to be 132 ± 44 km s-1 ranging from 57 to 264 km
s-1 along the propagation direction. The average lifetime
is 20 ± 6 ranging from 11 to 36 s. The speed and lifetime of the
jets are located at end-tails of those parameters determined for type
II spicules, hence implying a new type of jets. To confirm whether
these jets are different from conventional spicules, we construct
a time-height image averaged over a horizontal region of 1″, and
calculate lagged cross-correlations of intensity profiles at each height
with the intensity at 2 Mm. From this, we obtain a cross-correlation
map as a function of lag and height. We find that the correlation
curve as a function of lag time is well fitted into three different
Gaussian functions whose standard deviations of the lag time are 193,
42, and 17 s. The corresponding propagation speeds are calculated to be
9 km s-1, 67 km s-1, and 121 km s-1,
respectively. The kinematic properties of the former two components
seem to correspond to the 3-minute oscillations and type II spicules,
while the latter component to the jets is addressed in this study.
Title: Vortex Formations and Its Associated Surges in a Sunspot
Light Bridge
Authors: Yang, Heesu; Lim, Eun-Kyung; Iijima, Haruhisa; Yurchyshyn,
Vasyl; Cho, Kyung-Suk; Lee, Jeongwoo; Schmieder, Brigitte; Kim,
Yeon-Han; Kim, Sujin; Bong, Su-Chan
Bibcode: 2019ApJ...882..175Y
Altcode:
We report on the successive occurrence of 0.″5 wide photospheric
vortices with strong transverse shear flows at the edge of a sunspot
light bridge (LB), and the subsequent ejection of chromospheric surges
observed using a Visible Inteferometry Spectrograph, a broadband
TiO filter, and a Near InfRared Imaging Spectrograph of the Goode
Solar Telescope operating at Big Bear Solar Observatory. The Hα
surges ejected at the location of the vortices often appeared in
a hollow cylindrical structure. We also observed quasi-periodic
vortex-associated bright Hα plasma blobs moving upward with a speed
of up to 4 km s-1. In view of the strong shear flow at
the edge of the LB, it is likely that the vortices form under the
Kelvin-Helmholtz instability. The surges may result from either the
magnetic tension generated after magnetic reconnection or an acoustic
impulse of a fast photospheric transverse flow. Otherwise, the surges
could also be associated with Alfvénic waves, in which case their
origin could be torsional magnetic fields generated in the process of
the vortex formation.
Title: First cryogenic test operation of underground km-scale
gravitational-wave observatory KAGRA
Authors: Akutsu, T.; Ando, M.; Arai, K.; Arai, Y.; Araki, S.; Araya,
A.; Aritomi, N.; Asada, H.; Aso, Y.; Atsuta, S.; Awai, K.; Bae, S.;
Baiotti, L.; Barton, M. A.; Cannon, K.; Capocasa, E.; Chen, C. -S.;
Chiu, T. -W.; Cho, K.; Chu, Y. -K.; Craig, K.; Creus, W.; Doi, K.; Eda,
K.; Enomoto, Y.; Flaminio, R.; Fujii, Y.; Fujimoto, M. -K.; Fukunaga,
M.; Fukushima, M.; Furuhata, T.; Hagiwara, A.; Haino, S.; Hasegawa, K.;
Hashino, K.; Hayama, K.; Hirobayashi, S.; Hirose, E.; Hsieh, B. H.;
Huang, C. -Z.; Ikenoue, B.; Inoue, Y.; Ioka, K.; Itoh, Y.; Izumi,
K.; Kaji, T.; Kajita, T.; Kakizaki, M.; Kamiizumi, M.; Kanbara, S.;
Kanda, N.; Kanemura, S.; Kaneyama, M.; Kang, G.; Kasuya, J.; Kataoka,
Y.; Kawai, N.; Kawamura, S.; Kawasaki, T.; Kim, C.; Kim, J.; Kim,
J. C.; Kim, W. S.; Kim, Y. -M.; Kimura, N.; Kinugawa, T.; Kirii, S.;
Kitaoka, Y.; Kitazawa, H.; Kojima, Y.; Kokeyama, K.; Komori, K.; Kong,
A. K. H.; Kotake, K.; Kozu, R.; Kumar, R.; Kuo, H. -S.; Kuroyanagi,
S.; Lee, H. K.; Lee, H. M.; Lee, H. W.; Leonardi, M.; Lin, C. -Y.;
Lin, F. -L.; Liu, G. C.; Liu, Y.; Majorana, E.; Mano, S.; Marchio,
M.; Matsui, T.; Matsushima, F.; Michimura, Y.; Mio, N.; Miyakawa, O.;
Miyamoto, A.; Miyamoto, T.; Miyo, K.; Miyoki, S.; Morii, W.; Morisaki,
S.; Moriwaki, Y.; Morozumi, T.; Murakami, I.; Musha, M.; Nagano, K.;
Nagano, S.; Nakamura, K.; Nakamura, T.; Nakano, H.; Nakano, M.; Nakao,
K.; Namai, Y.; Narikawa, T.; Naticchioni, L.; Nguyen Quynh, L.; Ni,
W. -T.; Nishizawa, A.; Obuchi, Y.; Ochi, T.; Oh, J. J.; Oh, S. H.;
Ohashi, M.; Ohishi, N.; Ohkawa, M.; Okutomi, K.; Ono, K.; Oohara,
K.; Ooi, C. P.; Pan, S. -S.; Park, J.; Peña Arellano, F. E.; Pinto,
I.; Sago, N.; Saijo, M.; Saito, Y.; Saitou, S.; Sakai, K.; Sakai, Y.;
Sakai, Y.; Sasai, M.; Sasaki, M.; Sasaki, Y.; Sato, N.; Sato, S.; Sato,
T.; Sekiguchi, Y.; Seto, N.; Shibata, M.; Shimoda, T.; Shinkai, H.;
Shishido, T.; Shoda, A.; Somiya, K.; Son, E. J.; Suemasa, A.; Suzuki,
T.; Suzuki, T.; Tagoshi, H.; Tahara, H.; Takahashi, H.; Takahashi,
R.; Takamori, A.; Takeda, H.; Tanaka, H.; Tanaka, K.; Tanaka, T.;
Tanioka, S.; Tapia San Martin, E. N.; Tatsumi, D.; Terashima, S.;
Tomaru, T.; Tomura, T.; Travasso, F.; Tsubono, K.; Tsuchida, S.;
Uchikata, N.; Uchiyama, T.; Ueda, A.; Uehara, T.; Ueki, S.; Ueno, K.;
Uraguchi, F.; Ushiba, T.; van Putten, M. H. P. M.; Vocca, H.; Wada,
S.; Wakamatsu, T.; Watanabe, Y.; Xu, W. -R.; Yamada, T.; Yamamoto,
A.; Yamamoto, K.; Yamamoto, K.; Yamamoto, S.; Yamamoto, T.; Yokogawa,
K.; Yokoyama, J.; Yokozawa, T.; Yoon, T. H.; Yoshioka, T.; Yuzurihara,
H.; Zeidler, S.; Zhu, Z. -H.; KAGRA Collaboration
Bibcode: 2019CQGra..36p5008A
Altcode: 2019arXiv190103569K
KAGRA is a second-generation interferometric gravitational-wave
detector with 3 km arms constructed at Kamioka, Gifu, Japan. It is now
in its final installation phase, which we call bKAGRA (baseline KAGRA),
with scientific observations expected to begin in late 2019. One of the
advantages of KAGRA is its underground location of at least 200 m below
the ground surface, which reduces seismic motion at low frequencies
and increases the stability of the detector. Another advantage
is that it cools down the sapphire test mass mirrors to cryogenic
temperatures to reduce thermal noise. In April-May 2018, we operated
a 3 km Michelson interferometer with a cryogenic test mass for 10 d,
which was the first time that km-scale interferometer was operated at
cryogenic temperatures. In this article, we report the results of this
‘bKAGRA Phase 1’ operation. We have demonstrated the feasibility
of 3 km interferometer alignment and control with cryogenic mirrors.
Title: Vibration isolation system with a compact damping system for
power recycling mirrors of KAGRA
Authors: Akiyama, Y.; Akutsu, T.; Ando, M.; Arai, K.; Arai, Y.; Araki,
S.; Araya, A.; Aritomi, N.; Asada, H.; Aso, Y.; Bae, S.; Baiotti, L.;
Barton, M. A.; Cannon, K.; Capocasa, E.; Chen, C. -S.; Chiu, T. -W.;
Cho, K.; Chu, Y. -K.; Craig, K.; Dattilo, V.; Doi, K.; Enomoto, Y.;
Flaminio, R.; Fujii, Y.; Fujimoto, M. -K.; Fukunaga, M.; Fukushima,
M.; Furuhata, T.; Haino, S.; Hasegawa, K.; Hashimoto, Y.; Hashino, K.;
Hayama, K.; Hirayama, T.; Hirose, E.; Hsieh, B. H.; Huang, C. -Z.;
Ikenoue, B.; Inoue, Y.; Ioka, K.; Itoh, Y.; Izumi, K.; Kaji, T.;
Kajita, T.; Kakizaki, M.; Kamiizumi, M.; Kanbara, S.; Kanda, N.;
Kanemura, S.; Kang, G.; Kasuya, J.; Kawai, N.; Kawasaki, T.; Kim, C.;
Kim, W. S.; Kim, J.; Kim, J. C.; Kimura, N.; Kirii, S.; Kitaoka, Y.;
Kitazawa, H.; Kojima, Y.; Kokeyama, K.; Komori, K.; Kong, A.; Kotake,
K.; Kozu, R.; Kumar, R.; Kuo, H. -S.; Kuroki, S.; Kuroyanagi, S.; Lee,
H. K.; Lee, H. M.; Lee, H. W.; Leonardi, M.; Lin, C. -Y.; Lin, F. -L.;
Liu, G. C.; Marchio, M.; Matsui, T.; Michimura, Y.; Mio, N.; Miyakawa,
O.; Miyamoto, A.; Miyoki, S.; Morii, W.; Morisaki, S.; Moriwaki, Y.;
Musha, M.; Nagano, S.; Nagano, K.; Nakamura, K.; Nakamura, T.; Nakano,
H.; Nakano, M.; Narikawa, T.; Nguyen Quynh, L.; Ni, W. -T.; Nishizawa,
A.; Obuchi, Y.; Oh, J.; Oh, S. H.; Ohashi, M.; Ohishi, N.; Ohkawa, M.;
Okutomi, K.; Ono, K.; Oohara, K.; Ooi, C. P.; Pan, S. -S.; Paoletti,
F.; Park, J.; Passaquieti, R.; Peña Arellano, F. E.; Sago, N.; Saito,
S.; Saito, Y.; Sakai, K.; Sakai, Y.; Sasai, M.; Sato, S.; Sato, T.;
Sekiguchi, T.; Sekiguchi, Y.; Shibata, M.; Shimoda, T.; Shinkai, H.;
Shishido, T.; Shoda, A.; Someya, N.; Somiya, K.; Son, E. J.; Suemasa,
A.; Suzuki, T.; Suzuki, T.; Tagoshi, H.; Tahara, H.; Takahashi, H.;
Takahashi, R.; Takeda, H.; Tanaka, H.; Tanaka, K.; Tanaka, T.; Tanioka,
S.; Tapia San Martin, E. N.; Tomaru, T.; Tomura, T.; Travasso, F.;
Tsubono, K.; Tsuchida, S.; Uchikata, N.; Uchiyama, T.; Uehara, T.;
Ueno, K.; Uraguchi, F.; Ushiba, T.; van Putten, M. H. P. M.; Vocca,
H.; Wakamatsu, T.; Watanabe, Y.; Xu, W. -R.; Yamada, T.; Yamamoto, K.;
Yamamoto, K.; Yamamoto, S.; Yamamoto, T.; Yokogawa, K.; Yokoyama, J.;
Yokozawa, T.; Yoshioka, T.; Yuzurihara, H.; Zeidler, S.; Zhu, Z. -H.
Bibcode: 2019CQGra..36i5015A
Altcode: 2019arXiv190103053A
A vibration isolation system called the Type-Bp system used for power
recycling mirrors has been developed for KAGRA, the interferometric
gravitational-wave observatory in Japan. A suspension of the Type-Bp
system passively isolates an optic from seismic vibration using three
main pendulum stages equipped with two vertical vibration isolation
systems. A compact reaction mass around each of the main stages allows
for achieving sufficient damping performance with a simple feedback as
well as vibration isolation ratio. Three Type-Bp systems were installed
in KAGRA, and were proved to satisfy the requirements on the damping
performance, and also on estimated residual displacement of the optics.
Title: Oscillation of a Small Hα Surge in a Solar Polar Coronal Hole
Authors: Cho, Kyung-Suk; Cho, Il-Hyun; Nakariakov, V. M.; Yurchyshyn,
Vasyl B.; Yang, Heesu; Kim, Yeon-Han; Kumar, Pankaj; Magara, Tetsuya
Bibcode: 2019ApJ...877L...1C
Altcode:
Hα surges (i.e., cool/dense collimated plasma ejections) may act as
a guide for a propagation of magnetohydrodynamic waves. We report
a high-resolution observation of a surge observed with 1.6 m Goode
Solar Telescope (GST) on 2009 August 26, from 18:20 UT to 18:45
UT. Characteristics of plasma motions in the surge are determined
with the normalizing radial gradient filter and the Fourier motion
filter. The shape of the surge is found to change from a “C”
shape to an inverse “C” shape after a formation of a cusp, a
signature of reconnection. There are apparent upflows seen above
the cusp top and downflows below it. The upflows show rising and
rotational motions in the right-hand direction, with the rotational
speed decreasing with height. Near the cusp top, we find a transverse
oscillation of the surge, with the period of ∼2 minutes. There is no
change of the oscillation phase below the cusp top, but above the top
a phase change is identified, giving a vertical phase speed about 86
km s-1. As the height increases, the initial amplitude of
the oscillation increases, and the oscillation damping time decreases
from 5.13 to 1.18 minutes. We conclude that the oscillation is a
propagating kink wave that is possibly excited by the repetitive
spontaneous magnetic reconnection.
Title: Interplanetary Coronal Mass Ejections During Solar Cycles 23
and 24: Sun-Earth Propagation Characteristics and Consequences at
the Near-Earth Region
Authors: Syed Ibrahim, M.; Joshi, Bhuwan; Cho, K. -S.; Kim, R. -S.;
Moon, Y. -J.
Bibcode: 2019SoPh..294...54S
Altcode:
In this article, we present a statistical study probing the relation
between interplanetary coronal mass ejections (ICMEs) observed at
1 AU and their corresponding coronal mass ejections at the near-Sun
region. The work encompasses the ICME activity that occurred during
Solar Cycles 23 and 24 (1996 - 2017) while presenting an overall
picture of ICME events during the complete Solar Cycle 24 for the
first time. The importance of this study further lies in comparing two
subsets of ICMEs, i.e. magnetic clouds (MCs) and ejecta (EJ), to explore
how the observed structures of ICMEs at 1 AU could be associated with
the properties of CMEs during their launch at the Sun. We find that,
although Solar Cycle 24 saw a significant reduction in the number
of ICME events compared to the previous cycle, the fraction of MCs
was much higher during Cycle 24 than Cycle 23 (60% versus 41%). In
general, the ICME transit-time decreases with the increase in the CME
initial speed, although a broad range of transit times were observed
for a given CME speed. We also find that the high-speed ICMEs (≳500
kms−1) form a distinct group in terms of the deficit
in their transit times when compared with low-speed events (≲500
kms−1), which means that high-speed ICMEs acquire a
much higher internal energy from the source active regions during
the initiation process that effectively overcomes the aerodynamic
drag force while they transit in the interplanetary medium. The CME
propagation from the Sun to the near-Earth environment shows both
an overall positive and negative acceleration (i.e. deceleration),
although the acceleration is limited to only low-speed CMEs that are
launched with a speed comparable with or less than the mean solar
wind speed (≈400 -450 kms−1). Within a given cycle, the
similarities of MC and EJ profiles with respect to the CME-ICME speed
relation as well as interplanetary acceleration support the hypothesis
that all CMEs have a flux rope structure and that the trajectory of
the CMEs essentially determines the observed ICME structure at 1 AU.
Title: Solar activities and climate change during the last millennium
recorded in Korean chronicles
Authors: Yang, Hong-Jin; Park, Chan-Gyung; Kim, Rok-Soon; Cho,
Kyung-Suk; Jeon, Junhyeok
Bibcode: 2019JASTP.186..139Y
Altcode:
Korean chronicles have a large amount of observational records of
natural phenomena, including astronomical and meteorological events
over two thousand years. Here we examine the correlation of solar
activity and climate change from historical sunspot and frost records
in the Korean chronicles. There are 42 sunspot records in Goryeo
Dynasty (918-1392 CE) and 13 records in Joseon Dynasty (1392-1910
CE). The sunspot records in Goryeo Dynasty show a periodicity in good
agreement with the well-known solar activity of 11 years. Korean
sunspot records suggest that the solar activity in Joseon Dynasty
decreased compared with that in the previous ∼500 years. In order to
examine the long-period variation of solar activity, we include Chinese
historical sunspot records in our analysis to supplement the lack of
Korean records, and find a new ∼240-yr long-period solar activity
from the power spectral analysis. Korean chronicles also have about
700 frost records during the last millennium. We investigate these
frost records and find a sign of cooling down that can be interpreted
as climate change during the last millennium. We also find ∼240-yr
cooling period from the historical frost records, which is well in
accord with that of solar activity. Therefore, we conclude that the
solar activity has decreased during the last one thousand years and
also has a long-term variation of ∼240 years.
Title: Coronal electron density distributions from simultaneous
observations of solar corona with MK4, LASCO-C2, and SECCHI-COR1
Coronagraphs during the period from March 2007 to June 2007
Authors: Lee, Jae-Ok; Cho, Kyung-Suk
Bibcode: 2019EGUGA..2112308L
Altcode:
The coronal electron density is a fundamental and important physical
quantity in solar physics for estimating coronal magnetic fields
and analyzing solar radio bursts. Many ground- and space-based
white-light coronagraphs continuously measure polarized brightness
to estimate coronal electron density distributions (CEDDs). To
confirm the consistency of white-light coronagraph measurements and
determine CEDDs, we compare CEDDs derived from MK4 coronameter and
LASCO-C2 with Van de Hulst inversions and SECCHI-COR1A and COR1B with
spherically symmetric polynomial approximation (SSPA) by Wang et al.,
2014. For this, we consider coronagraph data from January to August
2007 with the following conditions: (1) the separation angle between
the either of the STEREO spacecraft and Earth is less than 10 degrees;
(2) the observation time differences from one another are less than 1
minutes; and (3) the data can be reasonably inverted to derive CEDDs;
(4) bright and faint streamer, and plume and inter-plume regions are
well observed in LASCO-C2 field of view. By investigating 15 events, 10
events are simultaneously observed by MK4, LASCO-C2, and SECCHI-COR1A
and 5 events are observed by MK4, LASCO-C2, and SECCHI-COR1B, we find
the following characteristics: (1) CEDDs are similar to one another at
broad- and faint- streamer regions (bright coronal structures) while
they are not similar to one another at plume and inter-plume regions
(faint coronal structures). Especially, there are very weak polarized
brightness near polar regions in SECCHI-COR1 observations, which are
similar to those of coronal backgrounds. (2) the average of estimated
CEDDs from 1.2 to 6 solar radii is 1.0-Fold Saito's density model at
bright streamer regions and 0.5-fold Saito's model at faint streamer
regions while it is 0.2-fold Saito's model at plume and inter-plume
regions. Our results indicate that not only kinematic studies of
bright coronal structures such as streamers and CMEs observed by using
white-light coronagraphs with different Field of View are reliable,
but also 1-fold Saito's model is a proper CEDDs at bright streamer
regions during solar minimum period.
Title: Solar farside magnetograms from deep learning analysis of
STEREO/EUVI data
Authors: Kim, Taeyoung; Park, Eunsu; Lee, Harim; Moon, Yong-Jae; Bae,
Sung-Ho; Lim, Daye; Jang, Soojeong; Kim, Lokwon; Cho, Il-Hyun; Choi,
Myungjin; Cho, Kyung-Suk
Bibcode: 2019NatAs...3..397K
Altcode: 2019NatAs.tmp..220K
Solar magnetograms are important for studying solar activity and
predicting space weather disturbances1. Farside magnetograms
can be constructed from local helioseismology without any farside
data2-4, but their quality is lower than that of typical
frontside magnetograms. Here we generate farside solar magnetograms
from STEREO/Extreme UltraViolet Imager (EUVI) 304-Å images using
a deep learning model based on conditional generative adversarial
networks (cGANs). We train the model using pairs of Solar Dynamics
Observatory (SDO)/Atmospheric Imaging Assembly (AIA) 304-Å images and
SDO/Helioseismic and Magnetic Imager (HMI) magnetograms taken from 2011
to 2017 except for September and October each year. We evaluate the
model by comparing pairs of SDO/HMI magnetograms and cGAN-generated
magnetograms in September and October. Our method successfully
generates frontside solar magnetograms from SDO/AIA 304-Å images
and these are similar to those of the SDO/HMI, with Hale-patterned
active regions being well replicated. Thus we can monitor the temporal
evolution of magnetic fields from the farside to the frontside of the
Sun using SDO/HMI and farside magnetograms generated by our model when
farside extreme-ultraviolet data are available. This study presents an
application of image-to-image translation based on cGANs to scientific
data.
Title: Seismological Determination of the Alfvén Speed and Plasma
Beta in Solar Photospheric Bright Points
Authors: Cho, Il-Hyun; Moon, Yong-Jae; Nakariakov, Valery M.; Yu,
Dae Jung; Lee, Jin-Yi; Bong, Su-Chan; Kim, Rok-Soon; Cho, Kyung-Suk;
Kim, Yeon-Han; Lee, Jae-Ok
Bibcode: 2019ApJ...871L..14C
Altcode: 2019arXiv190104144C
The Alfvén speed and plasma beta in photospheric bright points
(BPs) observed by the Broadband Filter Imager (BFI) of the Solar
Optical Telescope on board the Hinode satellite are estimated
seismologically. The diagnostics is based on the theory of slow
magnetoacoustic waves in a non-isothermally stratified photosphere
with a uniform vertical magnetic field. We identify and track BPs in a
G-band movie by using the 3D region growing method, and align them with
blue continuum images to derive their brightness temperatures. From the
Fourier power spectra of 118 continuum light curves made in the BPs,
we find that light curves of 91 BPs have oscillations with properties
that are significantly different from oscillation in quiet regions,
with the periods ranging 2.2-16.2 minutes. We find that the model
gives a moderate value of the plasma beta when γ lies at around
5/3. The calculated Alfvén speed is 9.68 ± 2.02 km s-1,
ranging in 6.3-17.4 km s-1. The plasma beta is estimated
to be of 0.93 ± 0.36, ranging in 0.2-1.9.
Title: KAGRA: 2.5 generation interferometric gravitational wave
detector
Authors: Kagra Collaboration; Akutsu, T.; Ando, M.; Arai, K.;
Arai, Y.; Araki, S.; Araya, A.; Aritomi, N.; Asada, H.; Aso, Y.;
Atsuta, S.; Awai, K.; Bae, S.; Baiotti, L.; Barton, M. A.; Cannon,
K.; Capocasa, E.; Chen, C. -S.; Chiu, T. -W.; Cho, K.; Chu, Y. -K.;
Craig, K.; Creus, W.; Doi, K.; Eda, K.; Enomoto, Y.; Flaminio, R.;
Fujii, Y.; Fujimoto, M. -K.; Fukunaga, M.; Fukushima, M.; Furuhata,
T.; Haino, S.; Hasegawa, K.; Hashino, K.; Hayama, K.; Hirobayashi,
S.; Hirose, E.; Hsieh, B. H.; Huang, C. -Z.; Ikenoue, B.; Inoue, Y.;
Ioka, K.; Itoh, Y.; Izumi, K.; Kaji, T.; Kajita, T.; Kakizaki, M.;
Kamiizumi, M.; Kanbara, S.; Kanda, N.; Kanemura, S.; Kaneyama, M.;
Kang, G.; Kasuya, J.; Kataoka, Y.; Kawai, N.; Kawamura, S.; Kawasaki,
T.; Kim, C.; Kim, J.; Kim, J. C.; Kim, W. S.; Kim, Y. -M.; Kimura,
N.; Kinugawa, T.; Kirii, S.; Kitaoka, Y.; Kitazawa, H.; Kojima, Y.;
Kokeyama, K.; Komori, K.; Kong, A. K. H.; Kotake, K.; Kozu, R.; Kumar,
R.; Kuo, H. -S.; Kuroyanagi, S.; Lee, H. K.; Lee, H. M.; Lee, H. W.;
Leonardi, M.; Lin, C. -Y.; Lin, F. -L.; Liu, G. C.; Liu, Y.; Majorana,
E.; Mano, S.; Marchio, M.; Matsui, T.; Matsushima, F.; Michimura, Y.;
Mio, N.; Miyakawa, O.; Miyamoto, A.; Miyamoto, T.; Miyo, K.; Miyoki,
S.; Morii, W.; Morisaki, S.; Moriwaki, Y.; Morozumi, T.; Musha, M.;
Nagano, K.; Nagano, S.; Nakamura, K.; Nakamura, T.; Nakano, H.; Nakano,
M.; Nakao, K.; Narikawa, T.; Naticchioni, L.; Nguyen Quynh, L.; Ni,
W. -T.; Nishizawa, A.; Obuchi, Y.; Ochi, T.; Oh, J. J.; Oh, S. H.;
Ohashi, M.; Ohishi, N.; Ohkawa, M.; Okutomi, K.; Ono, K.; Oohara,
K.; Ooi, C. P.; Pan, S. -S.; Park, J.; Peña Arellano, F. E.; Pinto,
I.; Sago, N.; Saijo, M.; Saitou, S.; Saito, Y.; Sakai, K.; Sakai, Y.;
Sakai, Y.; Sasai, M.; Sasaki, M.; Sasaki, Y.; Sato, S.; Sato, N.; Sato,
T.; Sekiguchi, Y.; Seto, N.; Shibata, M.; Shimoda, T.; Shinkai, H.;
Shishido, T.; Shoda, A.; Somiya, K.; Son, E. J.; Suemasa, A.; Suzuki,
T.; Suzuki, T.; Tagoshi, H.; Tahara, H.; Takahashi, H.; Takahashi,
R.; Takamori, A.; Takeda, H.; Tanaka, H.; Tanaka, K.; Tanaka, T.;
Tanioka, S.; Tapia San Martin, E. N.; Tatsumi, D.; Tomaru, T.; Tomura,
T.; Travasso, F.; Tsubono, K.; Tsuchida, S.; Uchikata, N.; Uchiyama,
T.; Uehara, T.; Ueki, S.; Ueno, K.; Uraguchi, F.; Ushiba, T.; van
Putten, M. H. P. M.; Vocca, H.; Wada, S.; Wakamatsu, T.; Watanabe,
Y.; Xu, W. -R.; Yamada, T.; Yamamoto, A.; Yamamoto, K.; Yamamoto,
K.; Yamamoto, S.; Yamamoto, T.; Yokogawa, K.; Yokoyama, J.; Yokozawa,
T.; Yoon, T. H.; Yoshioka, T.; Yuzurihara, H.; Zeidler, S.; Zhu, Z. -H.
Bibcode: 2019NatAs...3...35K
Altcode: 2018arXiv181108079A
The recent detections of gravitational waves (GWs) reported by the LIGO
and Virgo collaborations have made a significant impact on physics
and astronomy. A global network of GW detectors will play a key
role in uncovering the unknown nature of the sources in coordinated
observations with astronomical telescopes and detectors. Here we
introduce KAGRA, a new GW detector with two 3 km baseline arms arranged
in an `L' shape. KAGRA's design is similar to the second generations
of Advanced LIGO and Advanced Virgo, but it will be operating at
cryogenic temperatures with sapphire mirrors. This low-temperature
feature is advantageous for improving the sensitivity around 100 Hz
and is considered to be an important feature for the third-generation
GW detector concept (for example, the Einstein Telescope of Europe or
the Cosmic Explorer of the United States). Hence, KAGRA is often called
a 2.5-generation GW detector based on laser interferometry. KAGRA's
first observation run is scheduled in late 2019, aiming to join the
third observation run of the advanced LIGO-Virgo network. When operating
along with the existing GW detectors, KAGRA will be helpful in locating
GW sources more accurately and determining the source parameters with
higher precision, providing information for follow-up observations of
GW trigger candidates.
Title: Effects of Geometries and Substructures of ICMEs on Geomagnetic
Storms
Authors: Lee, Jae-Ok; Cho, Kyung-Suk; Kim, Rok-Soon; Jang, Soojeong;
Marubashi, Katsuhide
Bibcode: 2018SoPh..293..129L
Altcode:
To better understand geomagnetic storm generations by ICMEs, we consider
the effect of substructures (magnetic cloud, MC, and sheath) and
geometries (impact location of flux-rope at the Earth) of the ICMEs. We
apply the toroidal magnetic flux-rope model to 59 CDAW CME-ICME
pairs to identify their substructures and geometries, and select 20
MC-associated and five sheath-associated storm events. We investigate
the relationship between the storm strength indicated by minimum
Dst index (Dstmin) and solar wind conditions related to a
southward magnetic field. We find that all slopes of linear regression
lines for sheath-storm events are steeper (≥1.4 ) than those of the
MC-storm events in the relationship between Dstmin and solar
wind conditions, implying that the efficiency of sheath for the process
of geomagnetic storm generations is higher than that of MC. These
results suggest that different general solar wind conditions (sheaths
have a higher density, dynamic and thermal pressures with a higher
fluctuation of the parameters and higher magnetic fields than MCs) have
different impact on storm generation. Regarding the geometric encounter
of ICMEs, 100% (2/2) of major storms (Dstmin≤−100 nT)
occur in the regions at negative PY (relative position of
the Earth trajectory from the ICME axis in the Y component of the GSE
coordinate) when the eastern flanks of ICMEs encounter the Earth. We
find similar statistical trends in solar wind conditions, suggesting
that the dependence of geomagnetic storms on 3D ICME-Earth impact
geometries is caused by asymmetric distributions of the geoeffective
solar wind conditions. For western flank events, 80% (4/5) of the
major storms occur in positive PY regions, while intense
geoeffective solar wind conditions are not located in the positive
PY. These results suggest that the strength of geomagnetic
storms depends on ICME-Earth impact geometries as they determine the
solar wind conditions at Earth.
Title: Two-Dimensional Solar Wind Speeds from 6 to 26 Solar Radii
in Solar Cycle 24 by Using Fourier Filtering
Authors: Cho, Il-Hyun; Moon, Yong-Jae; Nakariakov, Valery M.; Bong,
Su-Chan; Lee, Jin-Yi; Song, Donguk; Lee, Harim; Cho, Kyung-Suk
Bibcode: 2018PhRvL.121g5101C
Altcode: 2018arXiv180608540C
Measurement of the solar wind speed near the Sun is important for
understanding the acceleration mechanism of the solar wind. In this
Letter, we determine 2D solar wind speeds from 6 to 26 solar radii
by applying Fourier motion filters to SOHO/LASCO C3 movies observed
from 1999 to 2010. Our method successfully reproduces the original flow
speeds in the artificially generated data as well as streamer blobs. We
measure 2D solar wind speeds from one-day to one-year timescales and
their variation in solar cycle 24. We find that the solar wind speeds
at timescales longer than a month in the solar maximum period are
relatively uniform in the azimuthal direction, while they are clearly
bimodal in the minimum period, as expected from the Ulysses observations
and interplanetary radio scintillation reconstruction. The bimodal
structure appears at around 2006, becomes most distinctive in 2009,
and abruptly disappears in 2010. The radial evolution of the solar
wind speeds resembles the Parker's solar wind solution.
Title: High-resolution Observations of a White-light Flare with
Goode Solar Telescope
Authors: Yurchyshyn, Vasyl; Kumar, Pankaj; Abramenko, Valentyna; Xu,
Yan; Goode, Philip R.; Cho, Kyung-Suk F.
Bibcode: 2018tess.conf21702Y
Altcode:
Using high resolution data from the Goode Solar Telescope (GST)
we studied the fine spatial and temporal structure of an M1.3 white
light (WL) flare, which was one of the three homologous solar flares
(C6.8, M1.3, and M2.3) observed in a close proximity to the west solar
limb. The RHESSI photon spectra for the M1.3 flare showed strongly
accelerated electrons with energies above 100 keV. Comparison of
HXR photon spectra for the three flares suggests that either thermal
energy of order of 1030 ergs and/or high energy electrons
(>50 keV) are necessary to produce a WL flare. The strong and
compact WL cores were ≈0.15 Mm across with an area of about
1014 cm2 . The observed TiO enhancements are
not normally distributed and are structured by the magnetic field of
the penumbra. Several of the TiO cores were not co-spatial with the Hα
emission, which suggests that the TiO and chromospheric emission did not
originate in the same chromospheric volume as some models suggest. We
thus conclude that fine temporal and spatial structure of the WL flare
was largely defined by the associated magnetic fields, which favors
the direct heating models, where the flare energy is directly deposited
in the temperature minimum region by the accelerated electrons.
Title: Simulation and Quasi-Linear Theory of Whistler Anisotropy
Instability
Authors: Lee, Sang-Yun; Lee, Ensang; Seough, Jungjoon; Lee, Jung-gi;
Hwang, Junga; Lee, Jae-Jin; Cho, Kyung-Suk; Yoon, Peter H.
Bibcode: 2018JGRA..123.3277L
Altcode:
The whistler anisotropy (or electromagnetic electron cyclotron)
instability may be operative in many geomagnetic and heliospherical
environments, including the radiation belt, solar wind, and the
solar corona. The present investigation carries out a comparative
analysis between the two-dimensional particle-in-cell simulation
of weakly growing whistler anisotropy instability and the velocity
moment-based two-dimensional quasi-linear theory under the assumption
of bi-Maxwellian electron distribution function. It is shown that the
simplified quasi-linear theory provides a qualitative agreement with
the more rigorous particle-in-cell simulation, but some discrepancies
are also found. Possible causes for the differences in either
method are discussed, and future improvements on the theory are
suggested. Potential applicability of the present finding in the
context of the space and astrophysics is discussed.
Title: Toward a Next Generation Solar Coronagraph: Diffracted Light
Simulation and Test Results for a Cone Occulter with Tapered Surface
Authors: Yang, Heesu; Bong, Su-Chan; Cho, Kyung-Suk; Choi, Seonghwan;
Park, Jongyeob; Kim, Jihun; Baek, Ji-Hye; Nah, Jakyoung; Sun, Mingzhe;
Gong, Qian
Bibcode: 2018JKAS...51...27Y
Altcode:
In a solar coronagraph, the most important component is an occulter to
block the direct light from the disk of the sun Because the intensity
of the solar outer corona is 10-6 to 10-10 times
of that of the solar disk (\ir), it is necessary to minimize scattering
at the optical elements and diffraction at the occulter. Using a Fourier
optic simulation and a stray light test, we investigated the performance
of a compact coronagraph that uses an external truncated-cone occulter
without an internal occulter and Lyot stop. In the simulation, the
diffracted light was minimized to the order of 7.6×10-10 \ir
when the cone angle θc was about 0.39°. The performance
of the cone occulter was then tested by experiment. The level of
the diffracted light reached the order of 6×10-9 \ir
at θc=0.40°. This is sufficient to observe the outer
corona without additional optical elements such as a Lyot stop or
inner occulter. We also found the manufacturing tolerance of the
cone angle to be 0.05°, the lateral alignment tolerance was 45 \um,
and the angular alignment tolerance was 0.043°. Our results suggest
that the physical size of coronagraphs can be shortened significantly
by using a cone occulter.
Title: Observation of the Kelvin-Helmholtz Instability in a Solar
Prominence
Authors: Yang, Heesu; Xu, Zhi; Lim, Eun-Kyung; Kim, Sujin; Cho,
Kyung-Suk; Kim, Yeon-Han; Chae, Jongchul; Cho, Kyuhyoun; Ji, Kaifan
Bibcode: 2018ApJ...857..115Y
Altcode:
Many solar prominences end their lives in eruptions or abrupt
disappearances that are associated with dynamical or thermal
instabilities. Such instabilities are important because they may be
responsible for energy transport and conversion. We present a clear
observation of a streaming kink-mode Kelvin-Helmholtz Instability (KHI)
taking place in a solar prominence using the Hα Lyot filter installed
at the New Vacuum Solar Telescope, Fuxian-lake Solar Observatory in
Yunnan, China. On one side of the prominence, a series of plasma blobs
floated up from the chromosphere and streamed parallel to the limb. The
plasma stream was accelerated to about 20-60 km s-1 and
then undulated. We found that 2″- and 5″-size vortices formed,
floated along the stream, and then broke up. After the 5″-size
vortex, a plasma ejection out of the stream was detected in the
Solar Dynamics Observatory/Atmospheric Imaging Assembly images. Just
before the formation of the 5″-size vortex, the stream displayed
an oscillatory transverse motion with a period of 255 s with the
amplitude growing at the rate of 0.001 s-1. We attribute
this oscillation of the stream and the subsequent formation of the
vortex to the KHI triggered by velocity shear between the stream,
guided by the magnetic field and the surrounding media. The plasma
ejection suggests the transport of prominence material into the upper
layer by the KHI in its nonlinear stage.
Title: Construction of KAGRA: an underground gravitational-wave
observatory
Authors: Akutsu, T.; Ando, M.; Araki, S.; Araya, A.; Arima, T.;
Aritomi, N.; Asada, H.; Aso, Y.; Atsuta, S.; Awai, K.; Baiotti, L.;
Barton, M. A.; Chen, D.; Cho, K.; Craig, K.; DeSalvo, R.; Doi, K.; Eda,
K.; Enomoto, Y.; Flaminio, R.; Fujibayashi, S.; Fujii, Y.; Fujimoto,
M. -K.; Fukushima, M.; Furuhata, T.; Hagiwara, A.; Haino, S.; Harita,
S.; Hasegawa, K.; Hasegawa, M.; Hashino, K.; Hayama, K.; Hirata, N.;
Hirose, E.; Ikenoue, B.; Inoue, Y.; Ioka, K.; Ishizaki, H.; Itoh, Y.;
Jia, D.; Kagawa, T.; Kaji, T.; Kajita, T.; Kakizaki, M.; Kakuhata,
H.; Kamiizumi, M.; Kanbara, S.; Kanda, N.; Kanemura, S.; Kaneyama,
M.; Kasuya, J.; Kataoka, Y.; Kawaguchi, K.; Kawai, N.; Kawamura,
S.; Kawazoe, F.; Kim, C.; Kim, J.; Kim, J. C.; Kim, W.; Kimura, N.;
Kitaoka, Y.; Kobayashi, K.; Kojima, Y.; Kokeyama, K.; Komori, K.;
Kotake, K.; Kubo, K.; Kumar, R.; Kume, T.; Kuroda, K.; Kuwahara, Y.;
Lee, H. -K.; Lee, H. -W.; Lin, C. -Y.; Liu, Y.; Majorana, E.; Mano,
S.; Marchio, M.; Matsui, T.; Matsumoto, N.; Matsushima, F.; Michimura,
Y.; Mio, N.; Miyakawa, O.; Miyake, K.; Miyamoto, A.; Miyamoto, T.;
Miyo, K.; Miyoki, S.; Morii, W.; Morisaki, S.; Moriwaki, Y.; Muraki,
Y.; Murakoshi, M.; Musha, M.; Nagano, K.; Nagano, S.; Nakamura, K.;
Nakamura, T.; Nakano, H.; Nakano, M.; Nakano, M.; Nakao, H.; Nakao,
K.; Narikawa, T.; Ni, W. -T.; Nonomura, T.; Obuchi, Y.; Oh, J. J.;
Oh, S. -H.; Ohashi, M.; Ohishi, N.; Ohkawa, M.; Ohmae, N.; Okino,
K.; Okutomi, K.; Ono, K.; Ono, Y.; Oohara, K.; Ota, S.; Park, J.;
Peña Arellano, F. E.; Pinto, I. M.; Principe, M.; Sago, N.; Saijo,
M.; Saito, T.; Saito, Y.; Saitou, S.; Sakai, K.; Sakakibara, Y.;
Sasaki, Y.; Sato, S.; Sato, T.; Sato, Y.; Sekiguchi, T.; Sekiguchi,
Y.; Shibata, M.; Shiga, K.; Shikano, Y.; Shimoda, T.; Shinkai, H.;
Shoda, A.; Someya, N.; Somiya, K.; Son, E. J.; Starecki, T.; Suemasa,
A.; Sugimoto, Y.; Susa, Y.; Suwabe, H.; Suzuki, T.; Tachibana, Y.;
Tagoshi, H.; Takada, S.; Takahashi, H.; Takahashi, R.; Takamori, A.;
Takeda, H.; Tanaka, H.; Tanaka, K.; Tanaka, T.; Tatsumi, D.; Telada,
S.; Tomaru, T.; Tsubono, K.; Tsuchida, S.; Tsukada, L.; Tsuzuki, T.;
Uchikata, N.; Uchiyama, T.; Uehara, T.; Ueki, S.; Ueno, K.; Uraguchi,
F.; Ushiba, T.; van Putten, M. H. P. M.; Wada, S.; Wakamatsu, T.;
Yaginuma, T.; Yamamoto, K.; Yamamoto, S.; Yamamoto, T.; Yano, K.;
Yokoyama, J.; Yokozawa, T.; Yoon, T. H.; Yuzurihara, H.; Zeidler,
S.; Zhao, Y.; Zheng, L.; Agatsuma, K.; Akiyama, Y.; Arai, N.; Asano,
M.; Bertolini, A.; Fujisawa, M.; Goetz, R.; Guscott, J.; Hashimoto,
Y.; Hayashida, Y.; Hennes, E.; Hirai, K.; Hirayama, T.; Ishitsuka,
H.; Kato, J.; Khalaidovski, A.; Koike, S.; Kumeta, A.; Miener,
T.; Morioka, M.; Mueller, C. L.; Narita, T.; Oda, Y.; Ogawa, T.;
Sekiguchi, T.; Tamura, H.; Tanner, D. B.; Tokoku, C.; Toritani, M.;
Utsuki, T.; Uyeshima, M.; van den Brand, J. F. J.; van Heijningen,
J. V.; Yamaguchi, S.; Yanagida, A.
Bibcode: 2018PTEP.2018a3F01A
Altcode: 2017arXiv171200148A
The major construction and initial-phase operation of a
second-generation gravitational-wave detector, KAGRA, has been
completed. The entire 3 km detector is installed underground in
a mine in order to be isolated from background seismic vibrations
on the surface. This allows us to achieve a good sensitivity at low
frequencies and high stability of the detector. Bare-bones equipment
for the interferometer operation has been installed and the first test
run was accomplished in March and April of 2016 with a rather simple
configuration. The initial configuration of KAGRA is called iKAGRA. In
this paper, we summarize the construction of KAGRA, including a study
of the advantages and challenges of building an underground detector,
and the operation of the iKAGRA interferometer together with the
geophysics interferometer that has been constructed in the same tunnel.
Title: Observation of a Large-scale Quasi-circular Secondary Ribbon
Associated with Successive Flares and a Halo CME
Authors: Lim, Eun-Kyung; Yurchyshyn, Vasyl; Kumar, Pankaj; Cho,
Kyuhyoun; Jiang, Chaowei; Kim, Sujin; Yang, Heesu; Chae, Jongchul;
Cho, Kyung-Suk; Lee, Jeongwoo
Bibcode: 2017ApJ...850..167L
Altcode: 2017arXiv171100622L
Solar flare ribbons provide an important clue to the magnetic
reconnection process and associated magnetic field topology in the
solar corona. We detected a large-scale secondary flare ribbon of
a circular shape that developed in association with two successive
M-class flares and one coronal mass ejection. The ribbon revealed
interesting properties such as (1) a quasi-circular shape and enclosing
the central active region (AR); (2) the size as large as 500″ by
650″ (3) successive brightenings in the clockwise direction at a
speed of 160 km s-1 starting from the nearest position to
the flaring sunspots; (4) radial contraction and expansion in the
northern and the southern part, respectively, at speeds of ≤10
km s-1. Using multi-wavelength data from Solar Dynamics
Observatory, RHESSI, XRT, and Nobeyama, along with magnetic field
extrapolations, we found that: (1) the secondary ribbon location is
consistent with those of the field line footpoints of a fan-shaped
magnetic structure that connects the flaring region and the ambient
decaying field; (2) the second M2.6 flare occurred when the expanding
coronal loops driven by the first M2.0 flare encountered the background
decayed field; (3) immediately after the second flare, the secondary
ribbon developed along with dimming regions. Based on our findings,
we suggest that interaction between the expanding sigmoid field and
the overlying fan-shaped field triggered the secondary reconnection
that resulted in the field opening and formation of the quasi-circular
secondary ribbon. We thus conclude that interaction between the AR and
the ambient large-scale fields should be taken into account to fully
understand the entire eruption process.
Title: Interplanetary Magnetic Flux Ropes as Agents Connecting Solar
Eruptions and Geomagnetic Activities
Authors: Marubashi, K.; Cho, K. -S.; Ishibashi, H.
Bibcode: 2017SoPh..292..189M
Altcode:
We investigate the solar wind structure for 11 cases that were
selected for the campaign study promoted by the International Study
of Earth-affecting Solar Transients (ISEST) MiniMax24 Working Group
4. We can identify clear flux rope signatures in nine cases. The
geometries of the nine interplanetary magnetic flux ropes (IFRs) are
examined with a model-fitting analysis with cylindrical and toroidal
force-free flux rope models. For seven cases in which magnetic fields in
the solar source regions were observed, we compare the IFR geometries
with magnetic structures in their solar source regions. As a result,
we can confirm the coincidence between the IFR orientation and the
orientation of the magnetic polarity inversion line (PIL) for six cases,
as well as the so-called helicity rule as regards the handedness of
the magnetic chirality of the IFR, depending on which hemisphere of
the Sun the IFR originated from, the northern or southern hemisphere;
namely, the IFR has right-handed (left-handed) magnetic chirality when
it is formed in the southern (northern) hemisphere of the Sun. The
relationship between the orientation of IFRs and PILs can be taken
as evidence that the flux rope structure created in the corona is in
most cases carried through interplanetary space with its orientation
maintained. In order to predict magnetic field variations on Earth
from observations of solar eruptions, further studies are needed about
the propagation of IFRs because magnetic fields observed at Earth
significantly change depending on which part of the IFR hits the Earth.
Title: Toward a Next Generation Solar Coronagraph: Development of
a Compact Diagnostic Coronagraph on the ISS
Authors: Cho, K. -S.; Bong, S. -C.; Choi, S.; Yang, H.; Kim, J.;
Baek, J. -H.; Park, J.; Lim, E. -K.; Kim, R. -S.; Kim, S.; Kim,
Y. -H.; Park, Y. -D.; Clarke, S. W.; Davila, J. M.; Gopalswamy, N.;
Nakariakov, V. M.; Li, B.; Pinto, R. F.
Bibcode: 2017JKAS...50..139C
Altcode:
The Korea Astronomy and Space Science Institute plans to develop
a coronagraph in collaboration with National Aeronautics and Space
Administration (NASA) and to install it on the International Space
Station (ISS). The coronagraph is an externally occulted one-stage
coronagraph with a field of view from 3 to 15 solar radii. The
observation wavelength is approximately 400 nm, where strong Fraunhofer
absorption lines from the photosphere experience thermal broadening and
Doppler shift through scattering by coronal electrons. Photometric
filter observations around this band enable the estimation of
2D electron temperature and electron velocity distribution in the
corona. Together with a high time cadence (<12 min) of corona images
used to determine the geometric and kinematic parameters of coronal
mass ejections, the coronagraph will yield the spatial distribution
of electron density by measuring the polarized brightness. For the
purpose of technical demonstration, we intend to observe the total
solar eclipse in August 2017 with the filter system and to perform a
stratospheric balloon experiment in 2019 with the engineering model
of the coronagraph. The coronagraph is planned to be installed on the
ISS in 2021 for addressing a number of questions (e.g., coronal heating
and solar wind acceleration) that are both fundamental and practically
important in the physics of the solar corona and of the heliosphere.
Title: A New Method for Coronal Magnetic Field Reconstruction
Authors: Yi, Sibaek; Choe, Gwang-Son; Cho, Kyung-Suk; Kim, Kap-Sung
Bibcode: 2017SPD....4810604Y
Altcode:
A precise way of coronal magnetic field reconstruction (extrapolation)
is an indispensable tool for understanding of various solar
activities. A variety of reconstruction codes have been developed so
far and are available to researchers nowadays, but they more or less
bear this and that shortcoming. In this paper, a new efficient method
for coronal magnetic field reconstruction is presented. The method
imposes only the normal components of magnetic field and current
density at the bottom boundary to avoid the overspecification of the
reconstruction problem, and employs vector potentials to guarantee the
divergence-freeness. In our method, the normal component of current
density is imposed, not by adjusting the tangential components of
A, but by adjusting its normal component. This allows us to avoid a
possible numerical instability that on and off arises in codes using
A. In real reconstruction problems, the information for the lateral
and top boundaries is absent. The arbitrariness of the boundary
conditions imposed there as well as various preprocessing brings about
the diversity of resulting solutions. We impose the source surface
condition at the top boundary to accommodate flux imbalance, which
always shows up in magnetograms. To enhance the convergence rate, we
equip our code with a gradient-method type accelerator. Our code is
tested on two analytical force-free solutions. When the solution is
given only at the bottom boundary, our result surpasses competitors
in most figures of merits devised by Schrijver et al. (2006). We have
also applied our code to a real active region NOAA 11974, in which two
M-class flares and a halo CME took place. The EUV observation shows
a sudden appearance of an erupting loop before the first flare. Our
numerical solutions show that two entwining flux tubes exist before the
flare and their shackling is released after the CME with one of them
opened up. We suggest that the erupting loop is created by magnetic
reconnection between two entwining flux tubes and later appears in
the coronagraph as the major constituent of the observed CME.
Title: Comparison of coronal electron density distributions from
MLSO/MK4, STEREO/SECCHI-COR1, SOHO/LASCO-C2, and SOHO/UVCS
Authors: Lee, Jae-Ok; Cho, Kyung-Suk; Lee, Jin-Yi; Lee, Kyoung-Sun;
Jang, Soojeong; Kim, Roksoon; Moon, Yong-Jae
Bibcode: 2017SPD....4810635L
Altcode:
The coronal electron density is a fundamental and important physical
quantity in solar physics. In this study, we compare coronal electron
density distributions (CEDDs) derived from polarized brightness (pB)
observations (MLSO/MK4 coronameter, STEREO/SECCHI-COR1 and SOHO/LASCO-C2
Coronagraphs) and one spectroscopic observation (SOHO/UVCS). For
this, we consider data from January to August 2007 with the following
conditions: the separation angle between the either of the STEREO
spacecraft and Earth is less than 10 degrees and the observation
time differences from one another are less than 1 minutes. In the pB
observations, the CEDDs can be estimated by using inversion methods
(Van de Hulst inversion for MK4 and LASCO-C2 pB data, and spherically
symmetric polynomial approximation inversion for COR1 pB data). In
the spectroscopic observation, we use the ratio of radiative and
collisional components of the O vi doublet (O vi 1032 Å and 1037.6
Å) to estimate the CEDDs. We will show you some results about the
estimated CEDDs and their dependence on different coronal regions such
as backgournd corona and streamers.
Title: Quasi-periodic Radio Bursts Associated with Fast-mode Waves
near a Magnetic Null Point
Authors: Kumar, Pankaj; Nakariakov, Valery M.; Cho, Kyung-Suk
Bibcode: 2017ApJ...844..149K
Altcode: 2017arXiv170609988K
This paper presents an observation of quasi-periodic rapidly propagating
waves observed in the Atmospheric Image Assembly (AIA) 171/193 Å
channels during the impulsive phase of an M1.9 flare that occurred on
2012 May 7. The instant period was found to decrease from 240 to 120
s, and the speed of the wavefronts was in the range of ∼664-1416
km s-1. Almost simultaneously, quasi-periodic bursts with
similar instant periods, ∼70 and ∼140 s, occur in the microwave
emission and in decimetric type IV and type III radio bursts, and in
the soft X-ray emission. The magnetic field configuration of the flare
site was consistent with a breakout topology, I.e., a quadrupolar
field along with a magnetic null point. The quasi-periodic rapidly
propagating wavefronts of the EUV emission are interpreted as a fast
magnetoacoustic wave train. The observations suggest that the fast-mode
waves are generated during the quasi-periodic magnetic reconnection
in the cusp region above the flare arcade loops. For the first time,
we provide evidence of a tadpole wavelet signature at about 70-140
s in decimetric (245/610 MHz) radio bursts, along with the direct
observation of a coronal fast-mode wave train in EUV. In addition, at
AIA 131/193 Å we observed quasi-periodic EUV disturbances with periods
of 95 and 240 s propagating downward at apparent speeds of 172-273 km
s-1. The nature of these downward propagating disturbances
is not revealed, but they could be connected to magnetoacoustic waves
or periodically shrinking loops.
Title: Multi-wavelength Observation of M-class Flare associated with
Filament eruption
Authors: Kim, Sujin; Yurchyshyn, Vasyl B.; Jiang, Chaowei; Cho,
Kyung-Suk
Bibcode: 2017SPD....4810822K
Altcode:
We have investigated a M-class flare associated with filament eruption
which developed into a Halo CME. The M-class flare occurred in 2011
August 4. For this study, we used the Nobryama Radioheliograph (NoRH)
17 and 34 GHz, RHESSI Hard X-ray satellite, and Atmo- spheric Imaging
Assembly (AIA) and the Heliospheric Magentic Imager(HMI) onboard the
Solar Dynamic Observatory (SDO). During the pre-eruption phase, clear
nonthermal emission was detected in microwaves of NoRH and hard-X-ray
of RHESSI. At the moment that the nonthermal emission start, the
nonthermal sources appeared at the one edge of the filament structure on
a polarity inversion line, and the slowing rising filament structure in
AIA 94A underwent a sudden acceleration on its ascendance. Magnetograms
showed converging motion of magnetic elements at the source position
of HXR and MW. Based on the results, we conjecture that the plausible
trigger of the filament eruption is magnetic reconnections at the HXR
source position by converging motion of magnetic elements. In addition,
we will discuss on the magnetic flux variation before and after the
eruption based on the result of Nonlinear force-free field model.
Title: Multiwavelength observations of a flux rope formation by
series of magnetic reconnection in the chromosphere
Authors: Kumar, Pankaj; Yurchyshyn, Vasyl; Cho, Kyung-Suk; Wang, Haimin
Bibcode: 2017A&A...603A..36K
Altcode: 2017arXiv170309871K
Using high-resolution observations from the 1.6 m New Solar Telescope
(NST) operating at the Big Bear Solar Observatory (BBSO), we report
direct evidence of merging and reconnection of cool Hα loops in the
chromosphere during two homologous flares (B and C class) caused by a
shear motion at the footpoints of two loops. The reconnection between
these loops caused the formation of an unstable flux rope that showed
counterclockwise rotation. The flux rope could not reach the height of
torus instability and failed to form a coronal mass ejection. The HMI
magnetograms revealed rotation of the negative and positive (N1/P2)
polarity sunspots in the opposite directions, which increased the
right- and left-handed twist in the magnetic structures rooted at
N1/P2. Rapid photospheric flux cancellation (duration 20-30 min,
rate ≈3.44 × 1020 Mx h-1) was observed
during and even after the first B6.0 flare and continued until
the end of the second C2.3 flare. The RHESSI X-ray sources were
located at the site of the loop coalescence. To the best of our
knowledge, such a clear interaction of chromospheric loops along
with rapid flux cancellation has not been reported before. These
high-resolution observations suggest the formation of a small flux
rope by a series of magnetic reconnections within chromospheric
loops that are associated with very rapid flux cancellation. Movies attached to Figs. 2, 7, 8, and 10 are available at http://www.aanda.org
Title: Investigating the Origins of Two Extreme Solar Particle Events:
Proton Source Profile and Associated Electromagnetic Emissions
Authors: Kocharov, Leon; Pohjolainen, Silja; Mishev, Alexander; Reiner,
Mike J.; Lee, Jeongwoo; Laitinen, Timo; Didkovsky, Leonid V.; Pizzo,
Victor J.; Kim, Roksoon; Klassen, Andreas; Karlicky, Marian; Cho,
Kyung-Suk; Gary, Dale E.; Usoskin, Ilya; Valtonen, Eino; Vainio, Rami
Bibcode: 2017ApJ...839...79K
Altcode:
We analyze the high-energy particle emission from the Sun in two
extreme solar particle events in which protons are accelerated to
relativistic energies and can cause a significant signal even in the
ground-based particle detectors. Analysis of a relativistic proton event
is based on modeling of the particle transport and interaction, from a
near-Sun source through the solar wind and the Earth’s magnetosphere
and atmosphere to a detector on the ground. This allows us to deduce
the time profile of the proton source at the Sun and compare it with
observed electromagnetic emissions. The 1998 May 2 event is associated
with a flare and a coronal mass ejection (CME), which were well
observed by the Nançay Radioheliograph, thus the images of the radio
sources are available. For the 2003 November 2 event, the low corona
images of the CME liftoff obtained at the Mauna Loa Solar Observatory
are available. Those complementary data sets are analyzed jointly
with the broadband dynamic radio spectra, EUV images, and other data
available for both events. We find a common scenario for both eruptions,
including the flare’s dual impulsive phase, the CME-launch-associated
decimetric-continuum burst, and the late, low-frequency type III
radio bursts at the time of the relativistic proton injection into
the interplanetary medium. The analysis supports the idea that the
two considered events start with emission of relativistic protons
previously accelerated during the flare and CME launch, then trapped
in large-scale magnetic loops and later released by the expanding CME.
Title: Impact of the Icme-Earth Geometry on the Strength of the
Associated Geomagnetic Storm: The September 2014 and March 2015 Events
Authors: Cho, K. S.; Marubashi, K.; Kim, R. S.; Park, S. H.; Lim,
E. K.; Kim, S. J.; Kumar, P.; Yurchyshyn, V.; Moon, Y. J.; Lee, J. O.
Bibcode: 2017JKAS...50...29C
Altcode:
No abstract at ADS
Title: Relation of CME Speed and Magnetic Helicity in CME Source
Regions on the Sun during the Early Phase of Solar Cycles 23 and 24
Authors: Kim, R. -S.; Park, S. -H.; Jang, S.; Cho, K. -S.; Lee, B. S.
Bibcode: 2017SoPh..292...66K
Altcode:
To investigate the relations between coronal mass ejection (CME) speed
and magnetic field properties measured in the photospheric surface of
CME source regions, we selected 22 disk CMEs in the rising and early
maximum phases of the current Solar Cycle 24. For the CME speed,
we used two-dimensional (2D) projected speed observed by the Large
Angle and Spectroscopic Coronagraph onboard the Solar and Heliospheric
Observatory (SOHO/LASCO), as well as a 3D speed calculated from the
triangulation method using multi-point observations. Two magnetic
parameters of CME source regions were considered: the average of
magnetic helicity injection rate and the total unsigned magnetic
flux. We then classified the selected CMEs into two groups, showing: i)
a monotonically increasing pattern with one sign of helicity (group A:
16 CMEs) and ii) a pattern of significant helicity injection followed
by its sign reversal (group B: 6 CMEs). We found that: 1) 3D speed
generally shows better correlations with the magnetic parameters than
the 2D speed for 22 CME events in Solar Cycle 24; 2) 2D speed and the
magnetic parameters of 22 CME events in this solar cycle have lower
values than those of 47 CME events in Solar Cycle 23; 3) all events of
group B in Solar Cycle 24 occur only after the beginning of the maximum
phase, a trend well consistent with that shown in Solar Cycle 23; 4)
the 2D speed and the helicity parameter of group B events continue to
increase in the declining phase of Solar Cycle 23, while those of group
A events abruptly decrease in the same period. Our results indicate
that the two CME groups have a different tendency in the solar cycle
variations of CME speed and the helicity parameters. Active regions that
show a complex helicity evolution pattern tend to appear in the maximum
and declining phases, while active regions with a relatively simple
helicity evolution pattern appear throughout the whole solar cycle.
Title: Which Bow Shock Theory, Gasdynamic or Magnetohydrodynamic,
Better Explains CME Stand-off Distance Ratios from LASCO-C2
Observations ?
Authors: Lee, Jae-Ok; Moon, Y. -J.; Lee, Jin-Yi; Kim, R. -S.; Cho,
K. -S.
Bibcode: 2017ApJ...838...70L
Altcode:
It is generally believed that fast coronal mass ejections (CMEs) can
generate their associated shocks, which are characterized by faint
structures ahead of CMEs in white-light coronagraph images. In this
study, we examine whether the observational stand-off distance ratio,
defined as the CME stand-off distance divided by its radius, can be
explained by bow shock theories. Of 535 SOHO/LASCO CMEs (from 1996 to
2015) with speeds greater than 1000 km s-1 and angular widths
wider than 60°, we select 18 limb CMEs with the following conditions:
(1) their Alfvénic Mach numbers are greater than one under Mann’s
magnetic field and Saito’s density distributions; and (2) the
shock structures ahead of the CMEs are well identified. We determine
observational CME stand-off distance ratios by using brightness profiles
from LASCO-C2 observations. We compare our estimates with theoretical
stand-off distance ratios from gasdynamic (GD) and magnetohydrodynamic
(MHD) theories. The main results are as follows. Under the GD theory,
39% (7/18) of the CMEs are explained in the acceptable ranges of
adiabatic gamma (γ) and CME geometry. Under the MHD theory, all the
events are well explained when we consider quasi-parallel MHD shocks
with γ = 5/3. When we use polarized brightness (pB) measurements
for coronal density distributions, we also find similar results: 8%
(1/12) under GD theory and 100% (12/12) under MHD theory. Our results
demonstrate that the bow shock relationships based on MHD theory are
more suitable than those based on GD theory for analyzing CME-driven
shock signatures.
Title: Characteristics of radio-loud CME
Authors: Pankaj Kumar; P. K., Manoharan; Cho, K. S.
Bibcode: 2017ursi.confE...1P
Altcode:
In this paper, we study the characteristics of 46 radio-loud (RL)
Coronal Mass Ejections (CMEs) which occurred during 1997-2006. All
these RL CMEs were associated with M- and X-class flares. We selected
46 RL CMEs, out of which 26 events (57%) were associated with Solar
Energetic Particle (SEP) events detected at 1 AU. Furthermore, we study
the link between the flare accelerated electrons in the low corona and
protons at 1 AU and found a positive correlation (30%). It suggests the
link between the injection sites for electrons and protons, which are
most likely accelerated at the flare current sheet. We also study the
relationship between the CME speed and peak proton flux (>10 MeV)
at 1 AU and found a good correlation ( 60%), which suggests the proton
acceleration by CME driven shocks. In addition, we found two branches
(lower and upper) of SEP events showing different characteristics. The
lower branch SEP events are associated with impulsive rise with more
proton flux whereas the upper branch SEP events exhibit gradual rise
and less proton flux. We suggest that flares (current sheet) and CMEs
(shocks) both are involved in the particle acceleration for the lower
branch, whereas in the upper branch mostly CME driven shocks play an
important role in the particle acceleration.
Title: High-resolution Observations of a White-light Flare with NST
Authors: Yurchyshyn, V.; Kumar, P.; Abramenko, V.; Xu, Y.; Goode,
P. R.; Cho, K. -S.; Lim, E. -K.
Bibcode: 2017ApJ...838...32Y
Altcode:
Using high-resolution data from the New Solar Telescope, we studied
fine spatial and temporal details of an M1.3 white-light (WL) flare,
which was one of three homologous solar flares (C6.8, M1.3, and M2.3)
observed in close proximity to the west solar limb on 2014 October 29
in NOAA active region 12192. We report that the TiO WL flare consists of
compact and intense cores surrounded by less intense spatial halos. The
strong and compact WL cores were measured to be ≈ 0.2 Mm across,
with an area of about 1014 cm2. Several TiO
features were not cospatial with Hα flare ribbons and were displaced
toward the disk center by about 500 km, which suggests that the TiO
and Hα radiation probably did not originate in the same chromospheric
volume. The observed TiO intensity enhancements are not normally
distributed and are structured by the magnetic field of the penumbra.
Title: Determination of the Alfvén Speed and Plasma-beta Using the
Seismology of Sunspot Umbra
Authors: Cho, I. -H.; Cho, K. -S.; Bong, S. -C.; Moon, Y. -J.;
Nakariakov, V. M.; Park, J.; Baek, J. -H.; Choi, S.; Kim, Y. -H.;
Lee, J.
Bibcode: 2017ApJ...837L..11C
Altcode:
For 478 centrally located sunspots observed in the optical continuum
with Solar Dynamics Observatory/Helioseismic Magnetic Imager,
we perform seismological diagnostics of the physical parameters of
umbral photospheres. The new technique is based on the theory of slow
magnetoacoustic waves in a non-isothermally stratified photosphere
with a uniform vertical magnetic field. We construct a map of the
weighted frequency of three-minute oscillations inside the umbra
and use it for the estimation of the Alfvén speed, plasma-beta,
and mass density within the umbra. We find the umbral mean Alfvén
speed ranges between 10.5 and 7.5 km s-1 and is negatively
correlated with magnetic field strength. The umbral mean plasma-beta
is found to range approximately between 0.65 and 1.15 and does not
vary significantly from pores to mature sunspots. The mean density
ranges between (1-6) × 10-4 kg m-3 and shows
a strong positive correlation with magnetic field strength.
Title: Observation of a Short Period Quasi-periodic Pulsation in
Solar X-Ray, Microwave, and EUV Emissions
Authors: Kumar, Pankaj; Nakariakov, Valery M.; Cho, Kyung-Suk
Bibcode: 2017ApJ...836..121K
Altcode: 2017arXiv170102159K
This paper presents the multiwavelength analysis of a 13 s
quasi-periodic pulsation (QPP) observed in hard X-ray (12-300 keV)
and microwave (4.9-34 GHz) emissions during a C-class flare that
occurred on 2015 September 21. Atmospheric Image Assembly (AIA) 304
and 171 Å images show an emerging loop/flux tube (L1) moving radially
outward, which interacts with the preexisting structures within the
active region (AR). The QPP was observed during the expansion of and
rising motion of L1. The Nobeyama Radioheliograph microwave images in
17/34 GHz channels reveal a single radio source that was co-spatial
with a neighboring loop (L2). In addition, using AIA 304 Å images,
we detected intensity oscillations in the legs of L2 with a period
of about 26 s. A similar oscillation period was observed in the GOES
soft X-ray flux derivative. This oscillation period seems to increase
with time. We suggest that the observed QPP is most likely generated
by the interaction between L2 and L3 observed in the AIA hot channels
(131 and 94 Å). The merging speed of loops L2 and L3 was ∼35 km
s-1. L1 was destroyed possibly by its interaction with
preexisting structures in the AR, and produced a cool jet with the
speed of ∼106-118 km s-1 associated with a narrow CME
(∼770 km s-1). Another mechanism of the QPP in terms of
a sausage oscillation of the loop (L2) is also possible.
Title: Chromospheric Plasma Ejections in a Light Bridge of a Sunspot
Authors: Song, Donguk; Chae, Jongchul; Yurchyshyn, Vasyl; Lim,
Eun-Kyung; Cho, Kyung-Suk; Yang, Heesu; Cho, Kyuhyoun; Kwak, Hannah
Bibcode: 2017ApJ...835..240S
Altcode: 2017arXiv170106808S
It is well-known that light bridges (LBs) inside a sunspot produce
small-scale plasma ejections and transient brightenings in the
chromosphere, but the nature and origin of such phenomena are still
unclear. Utilizing the high-spatial and high-temporal resolution
spectral data taken with the Fast Imaging Solar Spectrograph
and the TiO 7057 Å broadband filter images installed at the 1.6
m New Solar Telescope of Big Bear Solar Observatory, we report
arcsecond-scale chromospheric plasma ejections (1.″7) inside a
LB. Interestingly, the ejections are found to be a manifestation of
upwardly propagating shock waves as evidenced by the sawtooth patterns
seen in the temporal-spectral plots of the Ca II 8542 Å and Hα
intensities. We also found a fine-scale photospheric pattern (1″)
diverging with a speed of about 2 km s-1 two minutes before
the plasma ejections, which seems to be a manifestation of magnetic
flux emergence. As a response to the plasma ejections, the corona
displayed small-scale transient brightenings. Based on our findings,
we suggest that the shock waves can be excited by the local disturbance
caused by magnetic reconnection between the emerging flux inside the
LB and the adjacent umbral magnetic field. The disturbance generates
slow-mode waves, which soon develop into shock waves, and manifest
themselves as the arcsecond-scale plasma ejections. It also appears
that the dissipation of mechanical energy in the shock waves can heat
the local corona.
Title: Pre-eruption Oscillations in Thin and Long Features in a
Quiescent Filament
Authors: Joshi, Anand D.; Hanaoka, Yoichiro; Suematsu, Yoshinori;
Morita, Satoshi; Yurchyshyn, Vasyl; Cho, Kyung-Suk
Bibcode: 2016ApJ...833..243J
Altcode: 2016arXiv161204917J
We investigate the eruption of a quiescent filament located close to
an active region. Large-scale activation was observed in only half of
the filament in the form of pre-eruption oscillations. Consequently
only this half erupted nearly 30 hr after the oscillations
commenced. Time-slice diagrams of 171 Å images from the Atmospheric
Imaging Assembly were used to study the oscillations. These were
observed in several thin and long features connecting the filament
spine to the chromosphere below. This study traces the origin of
such features and proposes their possible interpretation. Small-scale
magnetic flux cancellation accompanied by a brightening was observed
at the footpoint of the features shortly before their appearance, in
images recorded by the Helioseismic and Magnetic Imager. A slow rise of
the filament was detected in addition to the oscillations, indicating
a gradual loss of equilibrium. Our analysis indicates that a change in
magnetic field connectivity between two neighbouring active regions
and the quiescent filament resulted in a weakening of the overlying
arcade of the filament, leading to its eruption. It is also suggested
that the oscillating features are filament barbs, and the oscillations
are a manifestation during the pre-eruption phase of the filaments.
Title: Pre-flare Coronal Jet and Evolutionary Phases of a Solar
Eruptive Prominence Associated with the M1.8 Flare: SDO and RHESSI
Observations
Authors: Joshi, Bhuwan; Kushwaha, Upendra; Veronig, Astrid M.; Cho,
K. -S.
Bibcode: 2016ApJ...832..130J
Altcode: 2016arXiv161103629J
We investigate the triggering, activation, and ejection of a solar
eruptive prominence that occurred in a multi-polar flux system of
active region NOAA 11548 on 2012 August 18 by analyzing data from the
Atmospheric Imaging Assembly on board the Solar Dynamics Observatory,
the Reuven Ramaty High Energy Solar Spectroscopic Imager, and the
Extreme Ultraviolet Imager/Sun Earth Connection Coronal and Heliospheric
Investigation on board the Solar Terrestrial Relation Observatory. Prior
to the prominence activation, we observed striking coronal activities in
the form of a blowout jet, which is associated with the rapid eruption
of a cool flux rope. Furthermore, the jet-associated flux rope eruption
underwent splitting and rotation during its outward expansion. These
coronal activities are followed by the prominence activation during
which it slowly rises with a speed of ∼12 km s-1 while
the region below the prominence emits gradually varying EUV and thermal
X-ray emissions. From these observations, we propose that the prominence
eruption is a complex, multi-step phenomenon in which a combination of
internal (tether-cutting reconnection) and external (I.e., pre-eruption
coronal activities) processes are involved. The prominence underwent
catastrophic loss of equilibrium with the onset of the impulsive
phase of an M1.8 flare, suggesting large-scale energy release by
coronal magnetic reconnection. We obtained signatures of particle
acceleration in the form of power-law spectra with hard electron
spectral index (δ ∼ 3) and strong HXR footpoint sources. During
the impulsive phase, a hot EUV plasmoid was observed below the apex
of the erupting prominence that ejected in the direction of the
prominence with a speed of ∼177 km s-1. The temporal,
spatial, and kinematic correlations between the erupting prominence
and the plasmoid imply that the magnetic reconnection supported the
fast ejection of prominence in the lower corona.
Title: The 17 March 2015 storm: the associated magnetic flux rope
structure and the storm development
Authors: Marubashi, Katsuhide; Cho, Kyung-Suk; Kim, Rok-Soon; Kim,
Sujin; Park, Sung-Hong; Ishibashi, Hiromitsu
Bibcode: 2016EP&S...68..173M
Altcode:
The objective of this study is (1) to determine the magnetic cloud
(MC) structure associated with the 17 March 2015 storm and (2) to
gain an insight into how the storm developed responding to the solar
wind conditions. First, we search MC geometries which can explain the
observed solar wind magnetic fields by fitting to both cylindrical
and toroidal flux rope models. Then, we examine how the resultant
MC geometries can be connected to the solar source region to find
out the most plausible model for the observed MC. We conclude that
the observations are most consistently explained by a toroidal flux
rope with the torus plane nearly parallel to the ecliptic plane. It
is emphasized that the observations are characterized by the peculiar
spacecraft crossing through the MC, in that the magnetic fields to be
observed are southward throughout the passage. For understanding of
the storm development, we first estimate the injection rate of the
storm ring current from the observed Dst variation. Then, we derive
an expression to calculate the estimated injection rate from the
observed solar wind variations. The point of the method is to evaluate
the injection rate by the convolution of the dawn-to-dusk electric
field in the solar wind and a response function. By using the optimum
response function thus determined, we obtain a modeled Dst variation
from the solar wind data, which is in good agreement with the observed
Dst variation. The agreement supports the validity of our method to
derive an expression for the ring current injection rate as a function
of the solar wind variation.[Figure not available: see fulltext.]
Title: Pre-Eruption Oscillations in Quiescent Filament Observed in
AIA 171 Å
Authors: Joshi, Anand D.; Yurchyshyn, Vasyl; Cho, Kyung-Suk
Bibcode: 2016usc..confE..62J
Altcode:
A large quiescent filament located near the south-west limb of the
Sun underwent an eruption on 14 August 2013. Shortly before the
eruption two flares occur in NOAA Active Region (AR) 11817, located
near the filament. The temporal and spatial proximity suggests that
the flares caused the filament to erupt. However, there is no extreme
ultraviolet (EUV) wave or ejection which seemed to cause this. We use
171 Å images for over two days before the eruption from Atmospheric
Imaging Assembly (AIA) on board Solar Dynamics Observatory (SDO) to
investigate this event. We observe oscillations in the western portion
of the quiescent filament almost 40 hours prior to eruption, but not
so much in the eastern portion. For several hours prior to eruption,
the western portion is seen to undergo a slow rise. Subsequently, it
is this western portion which erupts, while the eastern portion does
not. We also use Helioseismic and Magnetic Imager (HMI) to study changes
in the active region, and find that along with a continuous emergence
of magnetic flux in the region, there was also a migration of polarity
producing a large shear. We make use of the hmi.sharp to determine shear
in the active region. We suggest that the oscillations are a result of
natural perturbation, and the flares acted as a destabilising factor
which resulted in the eruption.
Title: Comparison of Damped Oscillations in Solar and Stellar
X-Ray flares
Authors: Cho, I. -H.; Cho, K. -S.; Nakariakov, V. M.; Kim, S.;
Kumar, P.
Bibcode: 2016ApJ...830..110C
Altcode:
We explore the similarity and difference of the quasi-periodic
pulsations (QPPs) observed in the decay phase of solar and stellar
flares at X-rays. We identified 42 solar flares with pronounced QPPs,
observed with RHESSI, and 36 stellar flares with QPPs, observed
with XMM-Newton. The empirical mode decomposition (EMD) method and
least-squares fit by a damped sine function were applied to obtain
the periods (P) and damping times (τ) of the QPPs. We found that (1)
the periods and damping times of the stellar QPPs are 16.21 ± 15.86
minutes and 27.21 ± 28.73 minutes, while those of the solar QPPs are
0.90 ± 0.56 and 1.53 ± 1.10 minutes, respectively; (2) the ratios of
the damping times to the periods (τ /P) observed in the stellar QPPs
(1.69 ± 0.56) are statistically identical to those of solar QPPs
(1.74 ± 0.77) and (3) the scalings of the QPP damping time with the
period are well described by the power law in both solar and stellar
cases. The power indices of the solar and stellar QPPs are 0.96 ±
0.10 and 0.98+/- 0.05, respectively. This scaling is consistent with
the scalings found for standing slow magnetoacoustic and kink modes in
solar coronal loops. Thus, we propose that the underlying mechanism
responsible for the stellar QPPs is the natural magnetohydrodynamic
oscillation in the flaring or adjacent coronal loops, as in the case
of solar flares.
Title: Flare-generated Shock Wave Propagation through Solar Coronal
Arcade Loops and an Associated Type II Radio Burst
Authors: Kumar, Pankaj; Innes, D. E.; Cho, Kyung-Suk
Bibcode: 2016ApJ...828...28K
Altcode: 2016arXiv160605056K
This paper presents multiwavelength observations of a flare-generated
type II radio burst. The kinematics of the shock derived from the type
II burst closely match a fast extreme ultraviolet (EUV) wave seen
propagating through coronal arcade loops. The EUV wave was closely
associated with an impulsive M1.0 flare without a related coronal mass
ejection, and was triggered at one of the footpoints of the arcade
loops in active region NOAA 12035. It was initially observed in the 335
Å images from the Atmospheric Image Assembly with a speed of ∼800
km s-1 and it accelerated to ∼1490 km s-1
after passing through the arcade loops. A fan-spine magnetic topology
was revealed at the flare site. A small, confined filament eruption
(∼340 km s-1) was also observed moving in the opposite
direction to the EUV wave. We suggest that breakout reconnection in
the fan-spine topology triggered the flare and associated EUV wave
that propagated as a fast shock through the arcade loops.
Title: Characteristics of radio-loud CMEs
Authors: Kumar, Pankaj; Manoharan, P. K.; Cho, K. S.
Bibcode: 2016ursi.confE...2K
Altcode:
In this paper, we study the characteristics of 46 radio-loud (RL)
Coronal Mass Ejections (CMEs) which occurred during 1997-2006. All
these RL CMEs were associated with M- and X-class flares. We selected
46 RL CMEs, out of which 26 events (57%) were associated with Solar
Energetic Particle (SEP) events detected at 1 AU. Furthermore, we study
the link between the flare accelerated electrons in the low corona and
protons at 1 AU and found a positive correlation (30%). It suggests
the link between the injection sites for electrons and protons, which
are most likely accelerated at the flare current sheet. We also study
the relation between the CME speed and peak proton flux (>10 MeV)
at 1 AU and found a good correlation (~60%), which suggests the proton
acceleration by CME-driven shocks. In addition, we found two branches
(lower and upper) of SEP events showing different characteristics. The
lower branch SEP events are associated with impulsive rise with more
proton flux whereas the upper branch SEP events exhibit gradual rise
and less proton flux. We suggest that flares (current sheet) and CMEs
(shocks) both are involved in the particle acceleration for the lower
branch, whereas in the upper branch mostly CME-driven shocks play an
important role in the particle acceleration.
Title: Ultra-Narrow Negative Flare Front Observed in Helium-10830
Å Using the1.6m New Solar Telescope
Authors: Xu, Yan; Cao, Wenda; Ding, Mingde; Kleint, Lucia; Su,
Jiangtao; Liu, Chang; Ji, Haisheng; Chae, Jongchul; Jing, Ju; Cho,
Kyuhyoun; Cho, Kyung-Suk; Gary, Dale E.; Wang, Haimin
Bibcode: 2016SPD....47.0633X
Altcode:
Solar flares are sudden flashes of brightness on the Sun and are often
associated with coronal mass ejections and solar energetic particles
that have adverse effects on the near-Earth environment. By definition,
flares are usually referred to as bright features resulting from excess
emission. Using the newly commissioned 1.6-m New Solar Telescope at
Big Bear Solar Observatory, we show a striking “negative” flare
with a narrow but unambiguous “dark” moving front observed in He I
10830 Å, which is as narrow as 340 km and is associated with distinct
spectral characteristics in Hα and Mg II lines. Theoretically, such
negative contrast in He I 10830 Å can be produced under special
circumstances by nonthermal electron collisions or photoionization
followed by recombination. Our discovery, made possible due to
unprecedented spatial resolution, confirms the presence of the required
plasma conditions and provides unique information in understanding
the energy release and radiative transfer in solar flares.
Title: Observation of a Quasiperiodic Pulsation in Hard X-Ray, Radio,
and Extreme-ultraviolet Wavelengths
Authors: Kumar, Pankaj; Nakariakov, Valery M.; Cho, Kyung-Suk
Bibcode: 2016ApJ...822....7K
Altcode: 2016arXiv160303121K
We present a multiwavelength analysis of a quasiperiodic pulsation (QPP)
observed in the hard X-ray (HXR), radio, and extreme-ultraviolet (EUV)
channels during an M1.9 flare that occurred on 2011 September 23-24. The
nonthermal HXR emission in 25-50 keV observed by RHESSI shows five
distinct impulsive peaks of decaying amplitude with a period of about 3
minutes. A similar QPP was observed in the microwave emission recorded
by the Nobeyama Radioheliograph and Polarimeter in the 2, 3.75, 9.4,
and 17 GHz channels. Interestingly, the 3-minute QPP was also observed
in the metric and decimetric radio frequencies (25-180, 245, 610 MHz) as
repetitive type III bursts. Multiwavelength observations from the Solar
Dynamics Observatory/Atmospheric Image Assembly, Hinode/SOT, and Solar
TErrestrial RElations Observatory/SECCHI suggest a fan-spine topology
at the eruption site, associated with the formation of a quasi-circular
ribbon during the flare. A small filament was observed below the fan
loops before the flare onset. The filament rose slowly and interacted
with the ambient field. This behavior was followed by an untwisting
motion of the filament. Two different structures of the filament
showed an approximately 3-minute periodic alternate rotation in the
clockwise and counterclockwise directions. The 3-minute QPP was found
to highly correlate with 3-minute oscillations in a nearby sunspot. We
suggest that the periodic reconnection (modulated either by a sunspot
slow-mode wave or by an untwisting filament) at a magnetic null point
most likely causes the repetitive particle acceleration, generating
the QPP observed in HXR, microwave, and type III radio bursts.
Title: Comparison between 2D and 3D Parameters of 306 Front-side
Halo CMEs from 2009 to 2013
Authors: Jang, Soojeong; Moon, Y. -J.; Kim, R. -S.; Lee, Harim; Cho,
K. -S.
Bibcode: 2016ApJ...821...95J
Altcode:
We investigate 306 LASCO front-side halo (partial and full) CMEs
from 2009 to 2013, which are well-observed by both the Solar and
Heliospheric Observatory (SOHO) and the Solar TErrestrial RElations
Observatory (STEREO). These CMEs have two-dimensional (2D) parameters,
such as speed, angular width, and propagation direction, from a single
spacecraft (SOHO), as well as three-dimensional (3D) parameters from a
multi-spacecraft (STEREO). These 2D CME parameters, which are based on
plane-of-sky observations, are taken from the SOHO LASCO CME catalog
and the NGDC flare catalog. We have determined their 3D CME parameters
using the Stereoscopic CME analysis tool (StereoCAT) provided by the
Community Coordinated Modeling Center at NASA. We compare 2D and 3D CME
parameters, making this the most comprehensive statistical study on CME
3D parameters. As a result, we find that 2D speeds underestimate the
3D speed by about 20%. The 3D width ranges from 30° to 158°, values
which are much smaller than the 2D widths with a mean value of 225°. We
also find that the ratio between the 2D and 3D widths decreases with
central meridian distance. The 3D propagation directions are similar to
the flare locations, with a mean absolute difference of about 13°. The
width-speed relationship in 3D is much stronger than that in 2D.
Title: a New Method to Determine the Temperature of CMES Using a
Coronagraph Filter System
Authors: Cho, Kyuhyoun; Chae, Jongchul; Lim, Eun-Kyung; Cho, Kyung-Suk;
Bong, Su-Chan; Yang, Heesu
Bibcode: 2016JKAS...49...45C
Altcode: 2016arXiv160307047C
The coronagraph is an instrument enables the investigation of faint
features in the vicinity of the Sun, particularly coronal mass ejections
(CMEs). So far coronagraphic observations have been mainly used to
determine the geometric and kinematic parameters of CMEs. Here, we
introduce a new method for the determination of CME temperature using
a two filter (4025 A and 3934 A) coronagraph system. The thermal motion
of free electrons in CMEs broadens the absorption lines in the optical
spectra that are produced by the Thomson scattering of visible light
originating in the photosphere, which affects the intensity ratio at two
different wavelengths. Thus the CME temperature can be inferred from
the intensity ratio measured by the two filter coronagraph system. We
demonstrate the method by invoking the graduated cylindrical shell
(GCS) model for the 3 dimensional CME density distribution and discuss
its significance.
Title: Observations of a Series of Flares and Associated Jet-like
Eruptions Driven by the Emergence of Twisted Magnetic Fields
Authors: Lim, Eun-Kyung; Yurchyshyn, Vasyl; Park, Sung-Hong; Kim,
Sujin; Cho, Kyung-Suk; Kumar, Pankaj; Chae, Jongchul; Yang, Heesu;
Cho, Kyuhyoun; Song, Donguk; Kim, Yeon-Han
Bibcode: 2016ApJ...817...39L
Altcode: 2015arXiv151201330L
We studied temporal changes of morphological and magnetic properties
of a succession of four confined flares followed by an eruptive flare
using the high-resolution New Solar Telescope (NST) operating at the Big
Bear Solar Observatory (BBSO) and Helioseismic and Magnetic Imager (HMI)
magnetograms and Atmospheric Image Assembly (AIA) EUV images provided by
the Solar Dynamics Observatory (SDO). From the NST/Hα and the SDO/AIA
304 Å observations we found that each flare developed a jet structure
that evolved in a manner similar to evolution of the blowout jet: (1)
an inverted-Y-shaped jet appeared and drifted away from its initial
position; (2) jets formed a curtain-like structure that consisted
of many fine threads accompanied by subsequent brightenings near
the footpoints of the fine threads; and finally, (3) the jet showed
a twisted structure visible near the flare maximum. Analysis of the
HMI data showed that both the negative magnetic flux and the magnetic
helicity have been gradually increasing in the positive-polarity region,
indicating the continuous injection of magnetic twist before and during
the series of flares. Based on these results, we suggest that the
continuous emergence of twisted magnetic flux played an important role
in producing successive flares and developing a series of blowout jets.
Title: Non-Uniqueness of the Geometry of Interplanetary Magnetic
Flux Ropes Obtained from Model-Fitting
Authors: Marubashi, K.; Cho, K. -S.
Bibcode: 2015SunGe..10..119M
Altcode:
Since the early recognition of the important role of interplanetary
magnetic flux ropes (IPFRs) to carry the southward magnetic fields
to the Earth, many attempts have been made to determine the structure
of the IPFRs by model-fitting analyses to the interplanetary magnetic
field variations. This paper describes the results of fitting analyses
for three selected solar wind structures in the latter half of 2014. In
the fitting analysis a special attention was paid to identification of
all the possible models or geometries that can reproduce the observed
magnetic field variation. As a result, three or four geometries have
been found for each of the three cases. The non-uniqueness of the fitted
results include (1) the different geometries naturally stemming from the
difference in the models used for fitting, and (2) an unexpected result
that either of magnetic field chirality, left-handed and right-handed,
can reproduce the observation in some cases. Thus we conclude that the
model-fitting cannot always give us a unique geometry of the observed
magnetic flux rope. In addition, we have found that the magnetic field
chirality of a flux rope cannot be uniquely inferred from the sense
of field vector rotation observed in the plane normal to the Earth-Sun
line; the sense of rotation changes depending on the direction of the
flux rope axis. These findings exert an important impact on the studies
aimed at the geometrical relationships between the flux ropes and the
magnetic field structures in the solar corona where the flux ropes
were produced, such studies being an important step toward predicting
geomagnetic storms based on observations of solar eruption phenomena.
Title: Development of AN Automatic Observation System for Korean
e-CALLISTO Station
Authors: Park, Jongyeob; Choi, Seonghwan; Bong, Su-Chan; Kwon,
Yongjun; Baek, Ji-Hye; Jang, Bi-Ho; Cho, Kyung-Suk; Moon, Yong-Jae;
Monstein, Christian
Bibcode: 2015PKAS...30..811P
Altcode:
No abstract at ADS
Title: Transfer of Real-time Dynamic Radiation Environment
Assimilation Model; Research to Operation
Authors: Cho, K. S. F.; Hwang, J.; Shin, D. K.; Kim, G. J.; Morley,
S.; Henderson, M. G.; Friedel, R. H.; Reeves, G. D.
Bibcode: 2015AGUFMSM41A2477C
Altcode:
Real-time Dynamic Radiation Environment Assimilation Model (rtDREAM)
was developed by LANL for nowcast of energetic electrons' flux at the
radiation belt to quantify potential risks from radiation damage at
the satellites. Assimilated data are from multiple sources including
LANL assets (GEO, GPS). For transfer from research to operation of
the rtDREAM code, LANL/KSWC/NOAA makes a Memorandum Of Understanding
(MOU) on the collaboration between three parts. By this MOU, KWSC/RRA
provides all the support for transitioning the research version of
DREAM to operations. KASI is primarily responsible for providing all
the interfaces between the current scientific output formats of the code
and useful space weather products that can be used and accessed through
the web. In the second phase, KASI will be responsible in performing
the work needed to transform the Van Allen Probes beacon data into
"DREAM ready" inputs. KASI will also provide the "operational" code
framework and additional data preparation, model output, display and
web page codes back to LANL and SWPC. KASI is already a NASA partnering
ground station for the Van Allen Probes' space weather beacon data
and can here show use and utility of these data for comparison between
rtDREAM and observations by web. NOAA has offered to take on some of
the data processing tasks specific to the GOES data.
Title: Multiwavelength Observations of a Slow-rise, Multistep X1.6
Flare and the Associated Eruption
Authors: Yurchyshyn, V.; Kumar, P.; Cho, K. -S.; Lim, E. -K.;
Abramenko, V. I.
Bibcode: 2015ApJ...812..172Y
Altcode:
Using multiwavelength observations, we studied a slow-rise, multistep
X1.6 flare that began on 2014 November 7 as a localized eruption of core
fields inside a δ-sunspot and later engulfed the entire active region
(AR). This flare event was associated with formation of two systems
of post-eruption arcades (PEAs) and several J-shaped flare ribbons
showing extremely fine details, irreversible changes in the photospheric
magnetic fields, and it was accompanied by a fast and wide coronal mass
ejection. Data from the Solar Dynamics Observatory and IRIS spacecraft,
along with the ground-based data from the New Solar Telescope, present
evidence that (i) the flare and the eruption were directly triggered
by a flux emergence that occurred inside a δ-sunspot at the boundary
between two umbrae; (ii) this event represented an example of the
formation of an unstable flux rope observed only in hot AIA channels
(131 and 94 Å) and LASCO C2 coronagraph images; (iii) the global
PEA spanned the entire AR and was due to global-scale reconnection
occurring at heights of about one solar radius, indicating the global
spatial and temporal scale of the eruption.
Title: Detection of a Fine-scale Discontinuity of Photospheric
Magnetic Fields Associated with Solar Coronal Loop Brightenings
Authors: Song, Donguk; Chae, Jongchul; Park, Soyoung; Cho, Kyung-Suk;
Lim, Eun-Kyung; Ahn, Kwangsu; Cao, Wenda
Bibcode: 2015ApJ...810L..16S
Altcode:
We present the transient brightening of a coronal loop and an associated
fine-scale magnetic discontinuity detected in the photosphere. Utilizing
the high-resolution data taken with the Fast Imaging Solar Spectrograph
and InfraRed Imaging Magnetograph of the New Solar Telescope at Big
Bear Solar Observatory, we detect a narrow lane of intense horizontal
magnetic field representing a magnetic discontinuity. It was visible
as a dark lane partially encircling a pore in the continuum image,
and was located near one of the footpoints of a small coronal loop
that experienced transient brightenings. The horizontal field strength
gradually increased before the loop brightening, and then rapidly
decreased in the impulsive phase of the brightening, suggesting the
increase of the magnetic non-potentiality at the loop footpoint and the
sudden release of magnetic energy via magnetic reconnection. Our results
support the nanoflare theory that coronal heating events are caused
by magnetic reconnection events at fine-scale magnetic discontinuities.
Title: Simultaneous observation of a hot explosion by NST and IRIS
Authors: Kim, Yeon-Han; Yurchyshyn, Vasyl; Bong, Su-Chan; Cho, Il-Hyun;
Cho, Kyung-Suk; Lee, Jaejin; Lim, Eun-Kyung; Park, Young-Deuk; Yang,
Heesu; Ahn, Kwangsu; Goode, Philip R.; Jang, Bi-Ho
Bibcode: 2015ApJ...810...38K
Altcode:
We present the first simultaneous observations of so-called “hot
explosions” in the cool atmosphere of the Sun made by the New Solar
Telescope (NST) of Big Bear Solar Observatory and the Interface Region
Imaging Spectrograph (IRIS) in space. The data were obtained during
the joint IRIS-NST observations on 2014 July 30. The explosion of
interest started around 19:20 UT and lasted for about 10 minutes. Our
findings are as follows: (1) the IRIS brightening was observed in
three channels of slit-jaw images, which cover the temperature range
from 4000 to 80,000 K; (2) during the brightening, the Si iv emission
profile showed a double-peaked shape with highly blue and redshifted
components (-40 and 80 km s-1) (3) wing brightening occurred
in Hα and Ca ii 8542 Å bands and related surges were observed in both
bands of the NST Fast Imaging Solar Spectrograph (FISS) instrument;
(4) the elongated granule, seen in NST TiO data, is clear evidence of
the emergence of positive flux to trigger the hot explosion; (5) the
brightening in Solar Dynamics Observatory/Atmospheric Imaging Assembly
1600 Å images is quite consistent with the IRIS brightening. These
observations suggest that our event is a hot explosion that occurred
in the cool atmosphere of the Sun. In addition, our event appeared as
an Ellerman bomb (EB) in the wing of Hα, although its intensity is
weak and the vertical extent of the brightening seems to be relatively
high compared with the typical EBs.
Title: Characteristics of four SPE groups with different origins
and acceleration processes
Authors: Kim, R. -S.; Cho, K. -S.; Lee, J.; Bong, S. -C.; Joshi,
A. D.; Park, Y. -D.
Bibcode: 2015JGRA..120.7083K
Altcode:
Solar proton events (SPEs) can be categorized into four groups based
on their associations with flare or CME inferred from onset timings
as well as acceleration patterns using multienergy observations. In
this study, we have investigated whether there are any typical
characteristics of associated events and acceleration sites in each
group using 42 SPEs from 1997 to 2012. We find the following: (i)
if the proton acceleration starts from a lower energy, a SPE has a
higher chance to be a strong event (> 5000 particle flux per unit
(pfu)) even if its associated flare and/or CME are not so strong. The
only difference between the SPEs associated with flare and CME is
the location of the acceleration site. (ii) For the former (Group A),
the sites are very low (∼ 1 Rs) and close to the western
limb, while the latter (Group C) have relatively higher (mean = 6.05
Rs) and wider acceleration sites. (iii) When the proton
acceleration starts from the higher energy (Group B), a SPE tends to be
a relatively weak event (< 1000 pfu), although its associated CME is
relatively stronger than previous groups. (iv) The SPEs categorized
by the simultaneous acceleration in whole energy range within 10
min (Group D) tend to show the weakest proton flux (mean = 327 pfu)
in spite of strong associated eruptions. Based on those results, we
suggest that the different characteristics of SPEs are mainly due to
the different conditions of magnetic connectivity and particle density,
which are changed with longitude and height as well as their origin.
Title: Solar Dynamics Observatory Data Search using Metadata in
the KDC
Authors: Hwang, E.; Choi, S.; Baek, J. -H.; Park, J.; Lee, J.; Cho, K.
Bibcode: 2015ASPC..495..539H
Altcode: 2015adass..24..539H
We have constructed the Korean Data Center (KDC) for the Solar Dynamics
Observatory (SDO) in the Korea Astronomy and Space Science Institute
(KASI). The SDO comprises three instruments; the Atmospheric Imaging
Assembly (AIA), the Helioseismic and Magnetic Imager (HMI), and the
Extreme Ultraviolet Variability Experiment (EVE). We archive AIA and
HMI FITS data. The size of data is about 1 TB of a day. The goal of
KDC for SDO is to provide easy and fast access service to the data
for researchers in Asia. In order to improve the data search rate, we
designed the system to search data without going through a process of
database query. The fields of instrument, wavelength, data path, date,
and time are saved as a text file. This metadata file and SDO FITS
data can be simply accessed via HTTP and are open to the public. We
present a process of creating metadata and a way to access SDO FITS
data in detail.
Title: Statistical Comparison Between Pores and Sunspots by Using
SDO/HMI
Authors: Cho, I. -H.; Cho, K. -S.; Bong, S. -C.; Lim, E. -K.; Kim,
R. -S.; Choi, S.; Kim, Y. -H.; Yurchyshyn, V.
Bibcode: 2015ApJ...811...49C
Altcode:
We carried out an extensive statistical study of the properties of
pores and sunspots, and investigated the relationship among their
physical parameters such as size, intensity, magnetic field, and the
line-of-sight (LOS) velocity in the umbrae. For this, we classified
9881 samples into three groups of pores, transitional sunspots, and
mature sunspots. As a result, (1) we find that the total magnetic
flux inside the umbra of pores, transitional sunspots, and mature
sunspots increases proportionally to the powers of the area and
the power indices in the three groups significantly differ from each
other. (2) The umbral area distribution of each group shows a Gaussian
distribution and they are clearly separated, displaying three distinct
peak values. All of the quantities significantly overlap among the three
groups. (3) The umbral intensity shows a rapid decrease with increasing
area, and their magnetic field strength shows a rapid increase with
decreasing intensity. (4) The LOS velocity in pores is predominantly
redshifted and its magnitude decreases with increasing magnetic field
strength. The decreasing trend becomes nearly constant with marginal
blueshift in the case of mature sunspots. The dispersion of LOS
velocities in mature sunspots is significantly suppressed compared
to pores. From our results, we conclude that the three groups have
different characteristics in their area, intensity, magnetic field,
and LOS velocity as well in their relationships.
Title: A Prestudy for the Development of a Compact Coronagraph
Authors: Bong, Su-Chan; Yang, Heesu; Cho, Kyuhyoun; Cho, Kyung-Suk;
Lim, Eun-Kyung; Park, Young-Deuk; Chae, Jongchul
Bibcode: 2015IAUGA..2254511B
Altcode:
We are conducting a prestudy for the development of a compact
coronagraph. The coronagraph is comprised of the external occulter,
lens, filter, and the CCD. We focus on the performance of the external
occulter, and the measurement of the coronal temperature and velocity
using a set of filters. We have tested the diffraction of a singlet
occulter and a cone occulter using laser. Compared to the singlet
occulter, the cone occulter gave rather symmetric, smooth and weak
diffraction pattern. We also have calculated the Thomson scattering of
the K corona to form coronal spectra in various temperature and velocity
conditions. We found the optimized wavelength set (393.4, 399.0, 402.5,
and 482.7 nm) for temperature and velocity measurement. We plan to
build a prototype coronagraph and make a test observation during the
total eclipse in 2016 without the occulter.
Title: Formation and Eruption of a Small Flux Rope in the Chromosphere
Observed by NST, IRIS, and SDO
Authors: Kumar, Pankaj; Yurchyshyn, Vasyl; Wang, Haimin; Cho, Kyung-Suk
Bibcode: 2015ApJ...809...83K
Altcode: 2015arXiv150701761K
Using high-resolution images from the 1.6 m New Solar Telescope
at Big Bear Solar Observatory, we report the direct evidence of
chromospheric reconnection at the polarity inversion line between
two small opposite polarity sunspots. Small jetlike structures
(with velocities of ∼20-55 km s-1) were observed at the
reconnection site before the onset of the first M1.0 flare. The slow
rise of untwisting jets was followed by the onset of cool plasma inflow
(∼10 km s-1) at the reconnection site, causing the onset
of a two-ribbon flare. The reconnection between two sheared J-shaped
cool Hα loops causes the formation of a small twisted (S-shaped) flux
rope in the chromosphere. In addition, Helioseismic and Magnetic Imager
magnetograms show the flux cancellation (both positive and negative)
during the first M1.0 flare. The emergence of negative flux and the
cancellation of positive flux (with shear flows) continue until the
successful eruption of the flux rope. The newly formed chromospheric
flux rope becomes unstable and rises slowly with a speed of ∼108 km
s-1 during a second C8.5 flare that occurred after ∼3
hr of the first M1.0 flare. The flux rope was destroyed by repeated
magnetic reconnection induced by its interaction with the ambient field
(fan-spine topology) and looks like an untwisting surge (∼170 km
s-1) in the coronal images recorded by the Solar Dynamics
Observatory/Atmospheric Imaging Assembly. These observations suggest
the formation of a chromospheric flux rope (by magnetic reconnection
associated with flux cancellation) during the first M1.0 flare and
its subsequent eruption/disruption during the second C8.5 flare.
Title: Causes of the Sep. 12-13, 2014 geomagnetic storms
Authors: Cho, Kyung-Suk; Kim, Rooksoon; Park, Sung-Hong; Kim, Sujin
Bibcode: 2015IAUGA..2249582C
Altcode:
Solar cycle 24 is very modest compared to previous solar cycles. The
solar maximum phase may have been reached in the middle of 2014 and
the sunspot number has decreased since the beginning of 2015. During
this period, it has been reported that only few events produced strong
X-class flares, solar proton events, and geomagnetic storms. In this
study we have investigated causes of the multiple geomagnetic storms
occurred on September 12-13, 2014. The geomagnetic storm forecast
model based on the CME observations was used for identification of
the causes of the geomagnetic storms. Details of the solar source
region were investigated to give an answer why the geomagnetic
storms were not so strong even though they were related to fast
coronal mass ejections with large earth-ward direction. As a result,
we found that the first weak storm was driven by the CME related to
M4.6 flare and the second minor storm was driven by one of the fast
CMEs related to strong X1.6 flare. Our result shows that the reason
why the second storm was not strong is that it was caused by the CME
with northward magnetic field. Therefore we suggest that one of the
essential ingredients for geomagnetic storm forecasting is to find
out the magnetic field direction of earth-ward CMEs, which can be
accomplished by investigating magnetic fields of their solar source
regions a few days before their arrival to the earth.
Title: A comprehensive catalog of 3D parameters of front-side halo
CMEs using STEREO and SOHO from 2009 to 2013
Authors: Jang, Soojeong; Moon, Yong-Jae; Kim, Rok-Soon; Lee, Harim;
Cho, Kyung-Suk
Bibcode: 2015shin.confE..85J
Altcode:
We present a comprehensive catalog of 308 front-side halo (partial and
full) CMEs from 2009 to 2013 observed by both SOHO and STEREO. This
catalog includes 2D CME parameters from single spacecraft (SOHO)
as well as 3D ones from multi-spacecraft. To determine the 3D CME
parameters (speed, angular width, and source location), we use the
STEREO CME analysis tool based on a triangulation method. In this
paper, we compare between 2D and 3D CME parameters, which is the
first statistical comparison between them. As a result, we find that
2D speeds tend to be about 20% underestimated when compared to 3D
ones. The 3D angular width ranges from 30° to 158°, which are much
smaller than the 2D angular widths with the mean value of 225°. We
also find that a ratio between 3D and 2D angular width increase with
central meridian distance. The 3D propagation directions are similar
to the flare locations. The angular width-speed relationship in 3D is
much stronger than that in 2D.
Title: Detection of Shock Merging in the Chromosphere of a Solar Pore
Authors: Chae, Jongchul; Song, Donguk; Seo, Minju; Cho, Kyung-Suk;
Park, Young-Deuk; Yurchyshyn, Vasyl
Bibcode: 2015ApJ...805L..21C
Altcode:
It was theoretically demonstrated that a shock propagating in the solar
atmosphere can overtake another and merge with it. We provide clear
observational evidence that shock merging does occur quite often in
the chromosphere of sunspots. Using Hα imaging spectral data taken by
the Fast Imaging Solar Spectrograph of the 1.6 m New Solar Telescope
at the Big Bear Soar Observatory, we construct time-distance maps
of line-of-sight velocities along two appropriately chosen cuts in
a pore. The maps show a number of alternating redshift and blueshift
ridges, and we identify each interface between a preceding redshift
ridge and the following blueshift ridge as a shock ridge. The important
finding of ours is that two successive shock ridges often merge with
each other. This finding can be theoretically explained by the merging
of magneto-acoustic shock waves propagating with lower speeds of about
10 km s-1 and those propagating at higher speeds of about
16-22 km s-1. The shock merging is an important nonlinear
dynamical process of the solar chromosphere that can bridge the gap
between higher-frequency chromospheric oscillations and lower-frequency
dynamic phenomena such as fibrils.
Title: X-Ray and EUV Observations of Simultaneous Short and Long
Period Oscillations in Hot Coronal Arcade Loops
Authors: Kumar, Pankaj; Nakariakov, Valery M.; Cho, Kyung-Suk
Bibcode: 2015ApJ...804....4K
Altcode: 2015arXiv150207117K
We report decaying quasi-periodic intensity oscillations in the X-ray
(6-12 keV) and extreme-ultraviolet (EUV) channels (131, 94, 1600, 304
Å) observed by the Fermi Gamma-ray Burst Monitor and Solar Dynamics
Observatory/Atmospheric Imaging Assembly (AIA), respectively, during a
C-class flare. The estimated periods of oscillation and decay time in
the X-ray channel (6-12 keV) were about 202 and 154 s, respectively. A
similar oscillation period was detected at the footpoint of the
arcade loops in the AIA 1600 and 304 Å channels. Simultaneously,
AIA hot channels (94 and 131 Å) reveal propagating EUV disturbances
bouncing back and forth between the footpoints of the arcade loops. The
period of the oscillation and decay time were about 409 and 1121 s,
respectively. The characteristic phase speed of the wave is about 560
km s-1 for about 115 Mm of loop length, which is roughly
consistent with the sound speed at the temperature about 10-16 MK
(480-608 km s-1). These EUV oscillations are consistent with
the Solar and Heliospheric Observatory/Solar Ultraviolet Measurement
of Emitted Radiation Doppler-shift oscillations interpreted as the
global standing slow magnetoacoustic wave excited by a flare. The
flare occurred at one of the footpoints of the arcade loops, where the
magnetic topology was a 3D fan-spine with a null-point. Repetitive
reconnection at this footpoint could have caused the periodic
acceleration of non-thermal electrons that propagated to the opposite
footpoint along the arcade and that are precipitating there, causing
the observed 202 s periodicity. Other possible interpretations, e.g.,
the second harmonics of the slow mode, are also discussed.
Title: Search for the Dark Photon and the Dark Higgs Boson at Belle
Authors: Jaegle, I.; Adachi, I.; Aihara, H.; Al Said, S.; Asner, D. M.;
Aushev, T.; Ayad, R.; Bakich, A. M.; Bansal, V.; Barrett, M.; Bhuyan,
B.; Bozek, A.; Bračko, M.; Browder, T. E.; Červenkov, D.; Chang,
M. -C.; Cheon, B. G.; Chilikin, K.; Cho, K.; Chobanova, V.; Choi,
S. -K.; Choi, Y.; Cinabro, D.; Dalseno, J.; Doležal, Z.; Drásal,
Z.; Drutskoy, A.; Dutta, D.; Eidelman, S.; Epifanov, D.; Farhat, H.;
Fast, J. E.; Ferber, T.; Frost, O.; Gaur, V.; Gabyshev, N.; Ganguly,
S.; Garmash, A.; Getzkow, D.; Gillard, R.; Goh, Y. M.; Golob, B.;
Grzymkowska, O.; Hayasaka, K.; Hayashii, H.; He, X. H.; Hedges, M.;
Hou, W. -S.; Iijima, T.; Inami, K.; Ishikawa, A.; Iwasaki, Y.; Julius,
T.; Kang, K. H.; Kato, E.; Kawasaki, T.; Kim, D. Y.; Kim, J. B.; Kim,
J. H.; Kim, S. H.; Kinoshita, K.; Ko, B. R.; Kodyš, P.; Korpar, S.;
Križan, P.; Krokovny, P.; Kuzmin, A.; Kwon, Y. -J.; Lange, J. S.; Lee,
I. S.; Lewis, P.; Li Gioi, L.; Libby, J.; Liventsev, D.; Matvienko, D.;
Miyata, H.; Mizuk, R.; Mohanty, G. B.; Moll, A.; Mussa, R.; Nakano,
E.; Nakao, M.; Nisar, N. K.; Nishida, S.; Ogawa, S.; Pakhlov, P.;
Pakhlova, G.; Park, H.; Pedlar, T. K.; Pesántez, L.; Petrič, M.;
Piilonen, L. E.; Ritter, M.; Rostomyan, A.; Sakai, Y.; Sandilya,
S.; Santelj, L.; Sanuki, T.; Sato, Y.; Savinov, V.; Schneider, O.;
Schnell, G.; Schwanda, C.; Semmler, D.; Senyo, K.; Seon, O.; Seong, I.;
Sevior, M. E.; Shebalin, V.; Shibata, T. -A.; Shiu, J. -G.; Shwartz,
B.; Simon, F.; Sinha, R.; Sohn, Y. -S.; Starič, M.; Sumihama, M.;
Sumisawa, K.; Tamponi, U.; Tatishvili, G.; Teramoto, Y.; Thorne, F.;
Uchida, M.; Uehara, S.; Unno, Y.; Uno, S.; Vahsen, S. E.; Van Hulse,
C.; Vanhoefer, P.; Varner, G.; Vinokurova, A.; Wagner, M. N.; Wang,
C. H.; Wang, M. -Z.; Wang, P.; Wang, X. L.; Watanabe, M.; Watanabe,
Y.; Williams, K. M.; Won, E.; Yamaoka, J.; Yashchenko, S.; Yook, Y.;
Yusa, Y.; Zhilich, V.; Zhulanov, V.; Zupanc, A.; Belle Collaboration
Bibcode: 2015PhRvL.114u1801J
Altcode: 2015arXiv150200084T
The dark photon A' and the dark Higgs boson h'
are hypothetical constituents featured in a number of recently proposed
dark sector models. Assuming prompt decays of both dark particles,
we search for their production in the so-called Higgstrahlung
channel e+e-→A'h' ,
with h'→A'A'. We investigate ten
exclusive final states with A'→e+e-,
μ+μ-, or π+π-
in the mass ranges 0.1 GeV /c2
<mA'<3.5 GeV /c2 and
0.2 GeV /c2 <mh'<10.5 GeV
/c2 . We also investigate three inclusive final states 2
(e+e-)X , 2 (μ+μ-)X ,
and (e+e-)(μ+μ-)X
, where X denotes a dark photon candidate detected via
missing mass, in the mass ranges 1.1 GeV /c2
<mA'<3.5 GeV /c2 and 2.2 GeV
/c2 <mh'<10.5 GeV /c2
. Using the entire 977 fb-1 data set collected by Belle,
we observe no significant signal. We obtain individual and combined
90% credibility level upper limits on the branching fraction times
the Born cross section, B ×σBorn , on the Born cross
section σBorn, and on the dark photon coupling to the
dark Higgs boson times the kinetic mixing between the standard
model photon and the dark photon, αD×ɛ2
. These limits improve upon and cover wider mass ranges
than previous experiments. The limits from the final states 3
(π+π-) and 2 (e+e-)X
are the first placed by any experiment. For αD equal to
1 /137 , mh'< 8 GeV /c2 , and
mA'<1 GeV /c2 , we exclude values
of the mixing parameter ɛ above ∼8 ×10-4.
Title: Geometrical Relationship Between Interplanetary Flux Ropes
and Their Solar Sources
Authors: Marubashi, K.; Akiyama, S.; Yashiro, S.; Gopalswamy, N.;
Cho, K. -S.; Park, Y. -D.
Bibcode: 2015SoPh..290.1371M
Altcode: 2015SoPh..tmp...46M
We investigated the physical connection between interplanetary flux
ropes (IFRs) near Earth and coronal mass ejections (CMEs) by comparing
the magnetic field structures of IFRs and CME source regions. The
analysis is based on the list of 54 pairs of ICMEs (interplanetary
coronal mass ejections) and CMEs that are taken to be the most probable
solar source events. We first attempted to identify the flux rope
structure in each of the 54 ICMEs by fitting models with a cylinder
and torus magnetic field geometry, both with a force-free field
structure. This analysis determined the possible geometries of the
identified flux ropes. Then we compared the flux rope geometries with
the magnetic field structure of the solar source regions. We obtained
the following results: (1) Flux rope structures are seen in 51 ICMEs
out of the 54. The result implies that all ICMEs have an intrinsic
flux rope structure, if the three exceptional cases are attributed to
unfavorable observation conditions. (2) It is possible to find flux rope
geometries with the main axis orientation close to the orientation of
the magnetic polarity inversion line (PIL) in the solar source regions,
the differences being less than 25°. (3) The helicity sign of an IFR
is strongly controlled by the location of the solar source: flux ropes
with positive (negative) helicity are associated with sources in the
southern (northern) hemisphere (six exceptions were found). (4) Over
two-thirds of the sources in the northern hemisphere are concentrated
along PILs with orientations of 45° ± 30° (measured clockwise from
the east), and over two-thirds in the southern hemisphere along PILs
with orientations of 135° ± 30°, both corresponding to the Hale
boundaries. These results strongly support the idea that a flux rope
with the main axis parallel to the PIL erupts in a CME and that the
erupted flux rope propagates through the interplanetary space with
its orientation maintained and is observed as an IFR.
Title: Intensity and Doppler Velocity Oscillations in Pore Atmospheres
Authors: Cho, K. -S.; Bong, S. -C.; Nakariakov, V. M.; Lim, E. -K.;
Park, Y. -D.; Chae, J. C.; Yang, H. -S.; Park, H. -M.; Yurchyshyn, V.
Bibcode: 2015ApJ...802...45C
Altcode:
We have investigated chromospheric traveling features running across two
merged pores from their centers at speeds of about 55 km s-1,
in the active region AR 11828. The pores were observed on 2013 August
24 by using high-time, spatial, and spectral resolution data from the
Fast Imaging Solar Spectrograph of the 1.6 m New Solar Telescope. We
infer a line-of-sight (LOS) velocity by applying the lambdameter method
to the Ca ii 8542 Å band and Hα band, and investigate intensity and
LOS velocity changes at different wavelengths and different positions
at the pores. We find that they have three-minute oscillations, and
the intensity oscillation from the line center (0.0 \overset{\circ}A
) is preceded by that from the core (-0.3 \overset{\circ}A ) of the
bands. There is no phase difference between the intensity and the
LOS velocity oscillations at a given wavelength. The amplitude of LOS
velocity from the near core spectra ({Δ }λ =0.10-0.21 \overset{\circ}A
) is greater than that from the far core spectra ({Δ }λ =0.24-0.36
\overset{\circ}A ). These results support the interpretation of the
observed wave as a slow magnetoacoustic wave propagating along the
magnetic field lines in the pores. The apparent horizontal motion and
a sudden decrease of its speed beyond the pores can be explained by
the projection effect caused by inclination of the magnetic field with
a canopy structure. We conclude that the observed wave properties of
the pores are quite similar to those from the sunspot observations.
Title: Burst Locating Capability of the Korean Solar Radio Burst
Locator (KSRBL)
Authors: Hwangbo, Jung-Eun; Bong, Su-Chan; Park, Sung-Hong; Lee,
Dae-Young; Cho, Kyung-Suk; Lee, Jaejin; Park, Young-Deuk
Bibcode: 2015JASS...32...91H
Altcode:
The Korean Solar Radio Burst Locator (KSRBL) is a solar radio
spectrograph observing the broad frequency range from 0.245 to 18 GHz
with the capability of locating wideband gyrosynchrotron bursts. Due to
the characteristics of a spiral feed, the beam center varies in a spiral
pattern with frequency, making a modulation pattern over the wideband
spectrum. After a calibration process, we obtained dynamic spectra
consistent with the Nobeyama Radio Polarimeter (NoRP). We compared and
analyzed the locations of bursts observed by KSRBL with results from
the Nobeyama Radioheliograph (NoRH) and Atmospheric Imaging Assembly
(AIA). As a result, we found that the KSRBL provides the ability to
locate flaring sources on the Sun within around 2'.
Title: A Trio of Confined Flares in AR 11087
Authors: Joshi, Anand D.; Forbes, Terry G.; Park, Sung-Hong; Cho,
Kyung-Suk
Bibcode: 2015ApJ...798...97J
Altcode:
We investigate three flares that occurred in active region, AR 11087,
observed by the Dutch Open Telescope (DOT) on 2010 July 13, in a
span of three hours. The first two flares have soft X-ray class B3,
whereas the third flare has class C3. The third flare not only was the
largest in terms of area and brightness but also showed a very faint
coronal mass ejection (CME) associated with it, while the earlier two
flares had no associated CME. The active region, located at 27° N,
26° E, has a small U-shaped active region filament to the south of
the sunspot, and a quiescent filament is located to its west. Hα
observations from DOT, as well as extreme-ultraviolet images and
magnetograms from the STEREO spacecraft and Solar Dynamics Observatory,
are used to study the dynamics of the active region during the three
flares. Our observations imply that the first two flares are confined
and that some filament material drains to the surface during these
flares. At the onset of the third flare downflows are again observed
within the active region, but a strong upflow is also observed at the
northern end of the adjacent quiescent filament to the west. It is at
the latter location that the CME originates. The temporal evolution of
the flare ribbons and the dynamics of the filaments are both consistent
with the idea that reconnection in a pre-existing current sheet leads
to a loss of equilibrium.
Title: Statistical Study on Personal Reduction Coefficients of
Sunspot Numbers Since 1981
Authors: Cho, Il-Hyun; Bong, Su-Chan; Cho, Kyung-Suk; Lee, Jaejin;
Kim, Rok-Soon; Park, Young-Deuk; Kim, Yeon-Han
Bibcode: 2014JKAS...47..255C
Altcode:
No abstract at ADS
Title: A refined classification of SPEs based on the multienergy
channel observations
Authors: Kim, R. -S.; Cho, K. -S.; Lee, J.; Bong, S. -C.; Park, Y. -D.
Bibcode: 2014JGRA..119.9419K
Altcode:
We have investigated characteristics of solar proton events (SPEs)
and their association with other types of solar eruption using 42
SPEs observed with SOlar and Heliospheric Observatory/Energetic
and Relativistic Nuclei and Electron detector from 1997 to 2012. A
velocity dispersion analysis was performed to correctly estimate the
onset times of proton flux increase at the solar vicinity. These SPE
onset times were compared with those of associated flares, coronal mass
ejections (CMEs), and interplanetary type II radio bursts. We found
that (i) the proton flux of 13 SPEs (31%) increase during the flare
X-ray intensity is increasing, and the rest 29 SPEs (69%) show onsets
well coincident with the first appearance of CMEs in Large Angle and
Spectrometric COronagraph field of view. (ii) All flare-associated
SPEs show the flux enhancements starting from the lower energy,
while the CME-associated SPEs show the flux enhancements starting
from either the higher or the lower energies. In the other events,
the flux enhancement occurs simultaneously at all energies within 10
min. (iii) For the former, large flux enhancements occur in a short
time, while the latter tend to show relatively weak and slow flux
enhancements. Our classification uses two criteria, SPE onset timing
relative to flares and energy-dependent flux enhancement, unlike
the conventional classification of SPEs based on whether the flux
time profile is impulsive or gradual. Nevertheless our classification
scheme refines the distinction between the flare-associated SPEs and the
CME-associated SPEs in terms of the onset timing. Additional information
on the proton acceleration as implied by the energy-dependent patterns
of flux enhancement is briefly discussed.
Title: Vertical Kink Oscillation of a Magnetic Flux Rope Structure
in the Solar Corona
Authors: Kim, S.; Nakariakov, V. M.; Cho, K. -S.
Bibcode: 2014ApJ...797L..22K
Altcode:
Vertical transverse oscillations of a coronal magnetic rope, observed
simultaneously in the 171 Å and 304 Å bandpasses of the Atmospheric
Imaging Assembly on board the Solar Dynamics Observatory (SDO), are
detected. The oscillation period is about 700 s and the displacement
amplitude is about 1 Mm. The oscillation amplitude remains constant
during the observation. Simultaneous observation of the rope in the
bandpasses corresponding to the coronal and chromospheric temperatures
suggests that it has a multi-thermal structure. Oscillatory patterns
in 171 Å and 304 Å are coherent, which indicates that the observed
kink oscillation is collective, in which the rope moves as a single
entity. We interpret the oscillation as a fundamental standing
vertically polarized kink mode of the rope, while the interpretation in
terms of a perpendicular fast wave could not be entirely ruled out. In
addition, the arcade situated above the rope and seen in the 171 Å
bandpass shows an oscillatory motion with the period of about 1000 s.
Title: KREAM: Korean Radiation Exposure Assessment Model for Aviation
Route Dose
Authors: Hwang, J.; Dokgo, K.; Choi, E. J.; Kim, K. C.; Kim, H. P.;
Cho, K. S. F.
Bibcode: 2014AGUFMSM31A4176H
Altcode:
Since Korean Air has begun to use the polar route from Seoul/ICN
airport to New York/JFK airport on August 2006, there are explosive
needs for the estimation and prediction against cosmic radiation
exposure for Korean aircrew and passengers in South Korea from
public. To keep pace with those needs of public, Korean government
made the law on safety standards and managements of cosmic radiation
for the flight attendants and the pilots in 2013. And we have begun
to develop our own Korean Radiation Exposure Assessment Model (KREAM)
for aviation route dose since last year funded by Korea Meteorological
Administration (KMA). GEANT4 model and NRLMSIS 00 model are used for
calculation of the energetic particles' transport in the atmosphere and
for obtaining the background atmospheric neutral densities depending on
altitude. For prediction the radiation exposure in many routes depending
on the various space weather effects, we constructed a database from
pre-arranged simulations using all possible combinations of R, S,
and G, which are the space weather effect scales provided by the
National Oceanic and Atmospheric Administration (NOAA). To get the
solar energetic particles' spectrum at the 100 km altitude which we
set as a top of the atmospheric layers in the KREAM, we use ACE and
GOES satellites' proton flux observations. We compare the results
between KREAM and the other cosmic radiation estimation programs such
as CARI-6M which is provided by the Federal Aviation Agency (FAA). We
also validate KREAM's results by comparison with the measurement from
Liulin-6K LET spectrometer onboard Korean commercial flights and Korean
Air Force reconnaissance flights.
Title: Multiwavelength observation of a large-scale flux rope eruption
above a kinked small filament
Authors: Kumar, Pankaj; Cho, Kyung-Suk
Bibcode: 2014A&A...572A..83K
Altcode: 2014arXiv1409.7213K
We analyzed multiwavelength observations of a western limb flare (C3.9)
that occurred in AR NOAA 111465 on 30 April 2012. The high-resolution
images recorded by SDO/AIA 304, 1600 Å and Hinode/SOT Hα show the
activation of a small filament (rising speed ~40 km s-1)
associated with a kink instability and the onset of a C-class
flare near the southern leg of the filament. The first magnetic
reconnection occurred at one of the footpoints of the filament and
caused the breaking of its southern leg. The filament shows unwinding
motion of the northern leg and apex in counterclockwise direction and
failed to erupt. A flux-rope structure (visible only in hot channels,
i.e., AIA 131 and 94 Å and Hinode/SXT) appeared along the neutral
line during the second magnetic reconnection that occurred above
the kinked filament. The formation of the RHESSI hard X-ray source
(12-25 keV) above the kinked filament and the simultaneous appearance
of the hot 131 Å loops associated with photospheric brightenings
(AIA 1700 Å) indicates the particle acceleration along these loops
from the top of the filament. In addition, extreme ultraviolet
disturbances or waves observed above the filament in 171 Å also
show a close association with magnetic reconnection. The flux rope
rises slowly (~100 km s-1), which produces a very large
twisted structure possibly through reconnection with the surrounding
sheared magnetic fields within ~15-20 min, and showed an impulsive
acceleration reaching a height of about 80-100 Mm. AIA 171 and SWAP 174
Å images reveal a cool compression front (or coronal mass ejection
frontal loop) surrounding the hot flux rope structure. Movies
associated with Figs. 2 and 7 are available in electronic form at http://www.aanda.org
Title: Magnetic Structure and Nonthermal Electrons in the X6.9 Flare
on 2011 August 09
Authors: Hwangbo, J. E.; Lee, J.; Park, S. H.; Bong, S. C.; Lee,
D. Y.; Kim, Y. H.; Cho, K. S. F.; Park, Y. D.
Bibcode: 2014AGUFMSH23A4155H
Altcode:
The 2011 August 09 Flare is one of the largest X-ray flares of Sunspot
Cycle 24, but the spatial information is rather limited due to its
position close to the western limb. This paper presents the information
on the location of high energy electrons derived from the hard X-ray
and microwave spectra obtained with the Reuven Ramaty High-Energy Solar
Spectroscopic Imager(RHESSI) and the Korean Solar Radio Burst Locator
(KSRBL), respectively. The KSRBL microwave spectrum shows significant
fluxes at low frequencies, implying that the high energy electrons
reside in a coronal volume highly concentrated at strong magnetic
fields, and rapidly expanding with decreasing magnetic fields. After a
simple modeling of the microwave spectrum, we found that the microwave
source should be located above the inner pair of magnetic poles in
a large quadrupolar configuration. The time-dependent evolution of
magnetic field distribution and total nonthermal energy derived from
the microwave spectra is also consistent with the standard picture
of multiple magnetic reconnections recurring at a magnetic null point
that forms above the magnetic quadrupoles and moves up with time.
Title: Kinematics of Solar Chromospheric Surges of AR 10930
Authors: Bong, Su-Chan; Cho, Kyung-Suk; Yurchyshyn, Vasyl
Bibcode: 2014JKAS...47..311B
Altcode:
No abstract at ADS
Title: Multi-wavelength Observation of Initiation Phase of Filament
Eruption
Authors: Kim, S.; Cho, K. S. F.; Park, S. H.
Bibcode: 2014AGUFMSH13B4102K
Altcode:
We have examined a nonthermal emission of a preflare activity associated
with M-class flare. This activity resulted in a filament eruption
that was developed into a halo CME. It was observed by microwave from
Nobeyama Radioheliograph (NoRH) at 17 GHz and 34 GHz, Hard X-ray
from Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI)
at 6-80 keV, and EUV from Atmospheric Imaging Assembly (AIA) onboard
Solar Dynamics Observatory (SDO). We found that a microwave nonthermal
source appeared near a southern footpoint of the filament system during
the preflare phase. Then it moved systematically away from there in the
direction parallel to two-ribbons together with the rapid eruption of
the filament system. It implies that the particle acceleration of the
flare started near the southern footpoint of the filament system and,
thus, it provided a decisive factor for the eruption of it. During the
preflare phase, Hard X-ray source also appeared in the position close
to microwave source and their source positions lined up depending on
their energy-bands. Unfortunately, there is no RHESSI data during the
main flare because it passed night-part of the earth. Here, we present
the detail investigation of physical parameters and emission mechanism
of the preflare nonthermal emission based on the imaging spectroscopy
of microwave and Hard X-ray.
Title: Magnetic Structure and Nonthermal Electrons in the X6.9 Flare
on 2011 August 9
Authors: Hwangbo, Jung-Eun; Lee, Jeongwoo; Park, Sung-Hong; Kim,
Sujin; Lee, Dae-Young; Bong, Su-Chan; Kim, Yeon-Han; Cho, Kyung-Suk;
Park, Young-Deuk
Bibcode: 2014ApJ...796...80H
Altcode:
The 2011 August 9 flare is one of the largest X-ray flares of sunspot
cycle 24, but spatial information is rather limited due to its position
close to the western limb. This paper presents information about
the location of high-energy electrons derived from hard X-ray and
microwave spectra obtained with the Reuven Ramaty High-Energy Solar
Spectroscopic Imager (RHESSI) and the Korean Solar Radio Burst Locator
(KSRBL), respectively. The KSRBL microwave spectrum shows significant
fluxes at low frequencies, implying that the high-energy electrons
reside in a coronal volume highly concentrated at strong magnetic
fields, and rapidly expanding with decreasing magnetic fields. After a
simple modeling of the microwave spectrum, we found that the microwave
source should be located above the inner pair of magnetic poles in a
large quadrupolar configuration. The time-dependent evolution of the
magnetic field distribution and total nonthermal energy derived from
the microwave spectra is also consistent with the standard picture
of multiple magnetic reconnections recurring at a magnetic null point
that forms above the magnetic quadrupoles and moves up with time.
Title: Active Region Coronal Rain Event Observed by the Fast Imaging
Solar Spectrograph on the NST
Authors: Ahn, Kwangsu; Chae, Jongchul; Cho, Kyung-Suk; Song, Donguk;
Yang, Heesu; Goode, Philip R.; Cao, Wenda; Park, Hyungmin; Nah,
Jakyung; Jang, Bi-Ho; Park, Young-Deuk
Bibcode: 2014SoPh..289.4117A
Altcode: 2014SoPh..tmp...98A
The Fast Imaging Solar Spectrograph (FISS) is being operated on the New
Solar Telescope of the Big Bear Solar Observatory. It simultaneously
records spectra of Hα and Ca II 8542 Å lines, and this dual-spectra
measurement provides an estimate of the temperature and nonthermal
speed components. We observed a loop structure in AR 11305 using the
FISS, SDO/AIA, and STEREO/EUVI in 304 Å, and found plasma material
falling along the loop from a coronal height into the umbra of a
sunspot, which accelerated up to 80 km s−1. We also
observed C2 and C7 flare events near the loop. The temperature of the
downflows was in the range of 10 000 - 33 000 K, increasing toward
the umbra. The temperature of the flow varied with time, and the
temperature near the footpoint rose immediately after the C7 flare,
but the temperature toward the umbra remained the same. There seemed
to be a temporal correlation between the amount of downflow material
and the observed C-class flares. The downflows decreased gradually soon
after the flares and then increased after a few hours. These high-speed
red-shift events occurred continuously during the observations. The
flows observed on-disk in Hα and Ca II 8542 Å appeared as fragmented,
fuzzy condensed material falling from the coronal heights when seen
off-limb with STEREO/EUVI at 304 Å. Based on these observations,
we propose that these flows were an on-disk signature of coronal rain.
Title: Impulsive Energy Release and Non-thermal Emission in a Confined
M4.0 Flare Triggered by Rapidly Evolving Magnetic Structures
Authors: Kushwaha, Upendra; Joshi, Bhuwan; Cho, Kyung-Suk; Veronig,
Astrid; Tiwari, Sanjiv Kumar; Mathew, S. K.
Bibcode: 2014ApJ...791...23K
Altcode: 2014arXiv1407.8115K
We present observations of a confined M4.0 flare from NOAA 11302
on 2011 September 26. Observations at high temporal, spatial, and
spectral resolution from the Solar Dynamics Observatory, Reuven Ramaty
High Energy Solar Spectroscopic Imager, and Nobeyama Radioheliograph
observations enabled us to explore the possible triggering and energy
release processes of this flare despite its very impulsive behavior
and compact morphology. The flare light curves exhibit an abrupt rise
of non-thermal emission with co-temporal hard X-ray (HXR) and microwave
(MW) bursts that peaked instantly without any precursor emission. This
stage was associated with HXR emission up to 200 keV that followed
a power law with photon spectral index (γ) ~ 3. Another non-thermal
peak, observed 32 s later, was more pronounced in the MW flux than the
HXR profiles. Dual peaked structures in the MW and HXR light curves
suggest a two-step magnetic reconnection process. Extreme ultraviolet
(EUV) images exhibit a sequential evolution of the inner and outer core
regions of magnetic loop systems while the overlying loop configuration
remained unaltered. Combined observations in HXR, (E)UV, and Hα
provide support for flare models involving the interaction of coronal
loops. The magnetograms obtained by the Helioseismic and Magnetic
Imager reveal emergence of magnetic flux that began ~five hr before the
flare. However, the more crucial changes in the photospheric magnetic
flux occurred about one minute prior to the flare onset with opposite
polarity magnetic transients appearing at the early flare location
within the inner core region. The spectral, temporal, and spatial
properties of magnetic transients suggest that the sudden changes
in the small-scale magnetic field have likely triggered the flare by
destabilizing the highly sheared pre-flare magnetic configuration.
Title: Superpenumbral Fibrils Powered by Sunspot Oscillations
Authors: Chae, Jongchul; Yang, Heesu; Park, Hyungmin; Ajor Maurya,
Ram; Cho, Kyung-Suk; Yurchysyn, Vasyl
Bibcode: 2014ApJ...789..108C
Altcode:
It is still a mystery how the solar chromosphere can stand high above
the photosphere. The dominant portion of this layer must be dynamically
supported, as is evident by the common occurrence of jets such as
spicules and mottles in quiet regions, and fibrils and surges in active
regions. Hence, revealing the driving mechanism of these chromospheric
jets is crucial for our understanding of how the chromosphere itself
exists. Here, we report our observational finding that fibrils in the
superpenumbra of a sunspot are powered by sunspot oscillations. We
find patterns of outward propagation that apparently originate from
inside the sunspot, propagate like running penumbral waves, and develop
into the fibrils. Redshift ridges seen in the time-distance plots of
velocity often merge, forming a fork-like pattern. The predominant
period of these shock waves increases, often jumping with distance,
from 3 minutes to 10 minutes. This short-to-long period transition
seems to result from the selective suppression of shocks by the
falling material of their preceding shocks. Based on our results,
we propose that the fibrils are driven by slow shock waves with long
periods that are produced by the merging of shock waves with shorter
periods propagating along the magnetic canopy.
Title: Introduction to the Space Weather Monitoring System at KASI
Authors: Baek, J.; Choi, S.; Kim, Y.; Cho, K.; Bong, S.; Lee, J.;
Kwak, Y.; Hwang, J.; Park, Y.; Hwang, E.
Bibcode: 2014ASPC..485..103B
Altcode: 2014adass..23..103B
We have developed the Space Weather Monitoring System (SWMS) at
the Korea Astronomy and Space Science Institute (KASI). Since 2007,
the system has continuously evolved into a better system. The SWMS
consists of several subsystems: applications which acquire and process
observational data, servers which run the applications, data storage,
and display facilities which show the space weather information. The
applications collect solar and space weather data from domestic and
oversea sites. The collected data are converted to other format and/or
visualized in real time as graphs and illustrations. We manage 3 data
acquisition and processing servers, a file service server, a web server,
and 3 sets of storage systems. We have developed 30 applications for
a variety of data, and the volume of data is about 5.5 GB per day. We
provide our customers with space weather contents displayed at the
Space Weather Monitoring Lab (SWML) using web services.
Title: Plasma Upflows and Microwave Emission in Hot Supra-arcade
Structure Associated with an M1.6 Limb Flare
Authors: Kim, S.; Shibasaki, K.; Bain, H. -M.; Cho, K. -S.
Bibcode: 2014ApJ...785..106K
Altcode:
We have investigated a supra-arcade structure associated with an
M1.6 flare, which occurred on the south-east limb on 2010 November
4. It is observed in EUV with the Atmospheric Imaging Assembly (AIA)
on board the Solar Dynamics Observatory, microwaves at 17 and 34 GHz
with the Nobeyama Radioheliograph (NoRH), and soft X-rays of 8-20
keV with RHESSI. Interestingly, we found exceptional properties of
the supra-arcade thermal plasma from the AIA 131 Å and the NoRH: (1)
plasma upflows along large coronal loops and (2) enhancing microwave
emission. RHESSI detected two soft X-ray sources, a broad one in the
middle of the supra-arcade structure and a bright one just above the
flare-arcade. We estimated the number density and thermal energy for
these two source regions during the decay phase of the flare. In the
supra-arcade source, we found that there were increases of the thermal
energy and the density at the early and last stages, respectively. On
the contrary, the density and thermal energy of the source on the top
of the flare-arcade decreases throughout. The observed upflows imply
that there is continuous energy supply into the supra-arcade structure
from below during the decay phase of the flare. It is hard to explain
by the standard flare model in which the energy release site is located
high in the corona. Thus, we suggest that a potential candidate of the
energy source for the hot supra-arcade structure is the flare-arcade,
which has exhibited a predominant emission throughout.
Title: 우주환경 지상관측기 자료통합시스템 개발
Title: 우주환경 지상관측기 자료통합시스템 개발
Title: Development of Data Integration System for Ground-Based Space
Weather Observational Facilities
Authors: Baek, Ji-Hye; Choi, Seonghwan; Lee, Jae-Jin; Kim, Yeon-Han;
Bong, Su-Chan; Park, Young-Deuk; Kwak, Young-Sil; Cho, Kyung-Suk;
Hwang, Junga; Jang, Bi-Ho; Yang, Tae-Yong; Hwang, Eunmi; Park,
Sung-Hong; Park, Jongyeob
Bibcode: 2013PKAS...28...65B
Altcode:
No abstract at ADS
Title: Temperature of Solar Prominences Obtained with the Fast Imaging
Solar Spectrograph on the 1.6 m New Solar Telescope at the Big Bear
Solar Observatory
Authors: Park, Hyungmin; Chae, Jongchul; Song, Donguk; Maurya, Ram
Ajor; Yang, Heesu; Park, Young-Deuk; Jang, Bi-Ho; Nah, Jakyoung; Cho,
Kyung-Suk; Kim, Yeon-Han; Ahn, Kwangsu; Cao, Wenda; Goode, Philip R.
Bibcode: 2013SoPh..288..105P
Altcode:
We observed solar prominences with the Fast Imaging Solar Spectrograph
(FISS) at the Big Bear Solar Observatory on 30 June 2010 and 15 August
2011. To determine the temperature of the prominence material, we
applied a nonlinear least-squares fitting of the radiative transfer
model. From the Doppler broadening of the Hα and Ca II lines, we
determined the temperature and nonthermal velocity separately. The
ranges of temperature and nonthermal velocity were 4000 - 20 000 K and
4 - 11 km s−1. We also found that the temperature varied
much from point to point within one prominence.
Title: Fast Imaging Solar Spectrograph of the 1.6 Meter New Solar
Telescope at Big Bear Solar Observatory
Authors: Chae, Jongchul; Park, Hyung-Min; Ahn, Kwangsu; Yang, Heesu;
Park, Young-Deuk; Nah, Jakyoung; Jang, Bi Ho; Cho, Kyung-Suk; Cao,
Wenda; Goode, Philip R.
Bibcode: 2013SoPh..288....1C
Altcode: 2012SoPh..tmp..248C
For high resolution spectral observations of the Sun - particularly
its chromosphere, we have developed a dual-band echelle spectrograph
named Fast Imaging Solar Spectrograph (FISS), and installed it in a
vertical optical table in the Coudé Lab of the 1.6 meter New Solar
Telescope at Big Bear Solar Observatory. This instrument can cover any
part of the visible and near-infrared spectrum, but it usually records
the Hα band and the Ca II 8542 Å band simultaneously using two CCD
cameras, producing data well suited for the study of the structure and
dynamics of the chromosphere and filaments/prominences. The instrument
does imaging of high quality using a fast scan of the slit across the
field of view with the aid of adaptive optics. We describe its design,
specifics, and performance as well as data processing
Title: Doppler Shifts of the Hα Line and the Ca II 854.2 nm Line
in a Quiet Region of the Sun Observed with the FISS/NST
Authors: Chae, Jongchul; Park, Hyung-Min; Ahn, Kwangsu; Yang, Heesu;
Park, Young-Deuk; Cho, Kyung-Suk; Cao, Wenda
Bibcode: 2013SoPh..288...89C
Altcode:
The characteristics of Doppler shifts in a quiet region of the Sun
are compared between the Hα line and the Ca II infrared line at 854.2
nm. A small area of 16″×40″ was observed for about half an hour
with the Fast Imaging Solar Spectrograph (FISS) of the 1.6 meter New
Solar Telescope (NST) at Big Bear Solar Observatory. The observed area
contains a network region and an internetwork region, and identified
in the network region are fibrils and bright points. We infer Doppler
velocity vm from each line profile at each individual point
with the lambdameter method as a function of half wavelength separation
Δλ. It is confirmed that the bisector of the spatially averaged Ca II
line profile has an inverse C-shape with a significant peak redshift of
+ 1.8 km s−1. In contrast, the bisector of the spatially
averaged Hα line profile has a C-shape with a small peak blueshift of
− 0.5 km s−1. In both lines, the bisectors of bright
network points are significantly redshifted not only at the line
centers, but also at the wings. The Ca II Doppler shifts are found
to be correlated with the Hα ones with the strongest correlation
occurring in the internetwork region. Moreover, we find that here the
Doppler shifts in the two lines are essentially in phase. We discuss
the physical implications of our results in view of the formation of
the Hα line and Ca II 854.2 nm line in the quiet region chromosphere.
Title: Study of Magnetic Helicity Injection in the Active Region NOAA
9236 Producing Multiple Flare-associated Coronal Mass Ejection Events
Authors: Park, Sung-Hong; Kusano, Kanya; Cho, Kyung-Suk; Chae,
Jongchul; Bong, Su-Chan; Kumar, Pankaj; Park, So-Young; Kim, Yeon-Han;
Park, Young-Deuk
Bibcode: 2013ApJ...778...13P
Altcode: 2013arXiv1308.5774P
To better understand a preferred magnetic field configuration and its
evolution during coronal mass ejection (CME) events, we investigated
the spatial and temporal evolution of photospheric magnetic fields in
the active region NOAA 9236 that produced eight flare-associated CMEs
during the time period of 2000 November 23-26. The time variations
of the total magnetic helicity injection rate and the total unsigned
magnetic flux are determined and examined not only in the entire
active region but also in some local regions such as the main sunspots
and the CME-associated flaring regions using SOHO/MDI magnetogram
data. As a result, we found that (1) in the sunspots, a large amount
of positive (right-handed) magnetic helicity was injected during most
of the examined time period, (2) in the flare region, there was a
continuous injection of negative (left-handed) magnetic helicity during
the entire period, accompanied by a large increase of the unsigned
magnetic flux, and (3) the flaring regions were mainly composed of
emerging bipoles of magnetic fragments in which magnetic field lines
have substantially favorable conditions for making reconnection with
large-scale, overlying, and oppositely directed magnetic field lines
connecting the main sunspots. These observational findings can also
be well explained by some MHD numerical simulations for CME initiation
(e.g., reconnection-favored emerging flux models). We therefore conclude
that reconnection-favored magnetic fields in the flaring emerging flux
regions play a crucial role in producing the multiple flare-associated
CMEs in NOAA 9236.
Title: FISS Observations of Vertical Motion of Plasma in Tiny Pores
Authors: Cho, K. -S.; Bong, S. -C.; Chae, J.; Kim, Y. -H.; Park,
Y. -D.; Katsukawa, Y.
Bibcode: 2013SoPh..288...23C
Altcode:
Pores can be exploited for the understanding of the interaction
between small-scale vertical magnetic field and the surrounding
convective motions as well as the transport of mechanical energy into
the chromosphere along the magnetic field. For better understanding of
the physics of pores, we investigate tiny pores in a new emerging
active region (AR11117) that were observed on 26 October 2010
by the Solar Optical Telescope (SOT) on board Hinode and the Fast
Imaging Solar Spectrograph (FISS) of the 1.6 meter New Solar Telescope
(NST). The pores are compared with nearby small magnetic concentrations
(SMCs), which have similar magnetic flux as the pores but do not
appear dark. Magnetic flux density and Doppler velocities in the
photosphere are estimated by applying the center-of-gravity method to
the Hinode/Spectro-Polarimeter data. The line-of-sight motions in the
lower chromosphere are determined by applying the bisector method to
the wings of the Hα and the Ca II 8542 Å line simultaneously taken
by the FISS. The coordinated observation reveals that the pores are
filled with plasma which moves down slowly and are surrounded by
stronger downflow in the photosphere. In the lower chromosphere, we
found that the plasma flows upwards inside the pores while the plasma
in the SMCs is always moving down. Our inspection of the Ca II 8542 Å
line from the wing to the core shows that the upflow in the pores slows
down with height and turns into downflow in the upper chromosphere
while the downflow in the SMCs gains its speed. Our results are in
agreement with the numerical studies which suggest that rapid cooling
of the interior of the pores drives a strong downflow, which collides
with the dense lower layer below and rebounds into an upflow.
Title: Simultaneous EUV and radio observations of bidirectional
plasmoids ejection during magnetic reconnection
Authors: Kumar, Pankaj; Cho, Kyung-Suk
Bibcode: 2013A&A...557A.115K
Altcode: 2013arXiv1307.3910K
We present a multiwavelength study of the X-class flare, which occurred
in active region (AR) NOAA 11339 on 3 November 2011. The extreme
ultraviolet (EUV) images recorded by SDO/AIA show the activation of a
remote filament (located north of the AR) with footpoint brightenings
about 50 min prior to the flare's occurrence. The kinked filament
rises up slowly, and after reaching a projected height of ~49 Mm,
it bends and falls freely near the AR, where the X-class flare was
triggered. Dynamic radio spectrum from the Green Bank Solar Radio Burst
Spectrometer (GBSRBS) shows simultaneous detection of both positive and
negative drifting pulsating structures (DPSs) in the decimetric radio
frequencies (500-1200 MHz) during the impulsive phase of the flare. The
global negative DPSs in solar flares are generally interpreted as
a signature of electron acceleration related to the upward-moving
plasmoids in the solar corona. The EUV images from AIA 94 Å reveal
the ejection of multiple plasmoids, which move simultaneously upward
and downward in the corona during the magnetic reconnection. The
estimated speeds of the upward- and downward-moving plasmoids
are ~152-362 and ~83-254 km s-1, respectively. These
observations strongly support the recent numerical simulations of the
formation and interaction of multiple plasmoids due to tearing of the
current-sheet structure. On the basis of our analysis, we suggest that
the simultaneous detection of both the negative and positive DPSs is
most likely generated by the interaction or coalescence of the multiple
plasmoids moving upward and downward along the current-sheet structure
during the magnetic reconnection process. Moreover, the differential
emission measure (DEM) analysis of the active region reveals a hot
flux-rope structure (visible in AIA 131 and 94 Å) prior to the flare
initiation and ejection of the multitemperature plasmoids during the
flare impulsive phase. Movie is available in electronic form at
http://www.aanda.org
Title: RHESSI and TRACE Observations of Multiple Flare Activity in
AR 10656 and Associated Filament Eruption
Authors: Joshi, Bhuwan; Kushwaha, Upendra; Cho, K. -S.; Veronig,
Astrid M.
Bibcode: 2013ApJ...771....1J
Altcode: 2013arXiv1305.1493J
We present Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI)
and Transition Region and Coronal Explorer (TRACE) observations of
multiple flare activity that occurred in the NOAA active region 10656
over a period of 2 hr on 2004 August 18. Out of four successive flares,
three were class C events, and the final event was a major X1.8 solar
eruptive flare. The activities during the pre-eruption phase, i.e.,
before the X1.8 flare, are characterized by three localized episodes of
energy release occurring in the vicinity of a filament that produces
intense heating along with non-thermal emission. A few minutes before
the eruption, the filament undergoes an activation phase during which
it slowly rises with a speed of ~12 km s-1. The filament
eruption is accompanied by an X1.8 flare, during which multiple hard
X-ray (HXR) bursts are observed up to 100-300 keV energies. We observe
a bright and elongated coronal structure simultaneously in E(UV)
and 50-100 keV HXR images underneath the expanding filament during
the period of HXR bursts, which provides strong evidence for ongoing
magnetic reconnection. This phase is accompanied by very high plasma
temperatures of ~31 MK, followed by the detachment of the prominence
from the solar source region. From the location, timing, strength,
and spectrum of HXR emission, we conclude that the prominence eruption
is driven by the distinct events of magnetic reconnection occurring in
the current sheet below the erupting prominence. These multi-wavelength
observations also suggest that the localized magnetic reconnections
associated with different evolutionary stages of the filament in
the pre-eruption phase play an important role in destabilizing the
active-region filament through the tether-cutting process, leading to
large-scale eruption and X-class flare.
Title: Propagation Characteristics of CMEs Associated with Magnetic
Clouds and Ejecta
Authors: Kim, R. -S.; Gopalswamy, N.; Cho, K. -S.; Moon, Y. -J.;
Yashiro, S.
Bibcode: 2013SoPh..284...77K
Altcode:
We have investigated the characteristics of magnetic cloud (MC)
and ejecta (EJ) associated coronal mass ejections (CMEs) based on
the assumption that all CMEs have a flux rope structure. For this,
we used 54 CMEs and their interplanetary counterparts (interplanetary
CMEs: ICMEs) that constitute the list of events used by the NASA/LWS
Coordinated Data Analysis Workshop (CDAW) on CME flux ropes. We
considered the location, angular width, and speed as well as the
direction parameter, D. The direction parameter quantifies the degree of
asymmetry of the CME shape in coronagraph images, and shows how closely
the CME propagation is directed to Earth. For the 54 CDAW events,
we found the following properties of the CMEs: i) the average value
of D for the 23 MCs (0.62) is larger than that for the 31 EJs (0.49),
which indicates that the MC-associated CMEs propagate more directly
toward the Earth than the EJ-associated CMEs; ii) comparison between
the direction parameter and the source location shows that the majority
of the MC-associated CMEs are ejected along the radial direction, while
many of the EJ-associated CMEs are ejected non-radially; iii) the mean
speed of MC-associated CMEs (946 km s−1) is faster than
that of EJ-associated CMEs (771 km s−1). For seven very
fast CMEs (≥ 1500 km s−1), all CMEs with large D (≥
0.4) are associated with MCs and the CMEs with small D are associated
with EJs. From the statistical analysis of CME parameters, we found
the superiority of the direction parameter. Based on these results,
we suggest that the CME trajectory essentially determines the observed
ICME structure.
Title: Observation of a Non-radial Penumbra in a Flux Emerging Region
under Chromospheric Canopy Fields
Authors: Lim, Eun-Kyung; Yurchyshyn, Vasyl; Goode, Philip; Cho,
Kyung-Suk
Bibcode: 2013ApJ...769L..18L
Altcode:
The presence of a penumbra is one of the main properties of a mature
sunspot, but its formation mechanism has been elusive due to a lack
of observations that fully cover the formation process. Utilizing the
New Solar Telescope at the Big Bear Solar Observatory, we observed
the formation of a partial penumbra for about 7 hr simultaneously at
the photospheric (TiO; 7057 Å) and the chromospheric (Hα - 1 Å)
spectral lines with high spatial and temporal resolution. From this
uninterrupted, long observing sequence, we found that the formation of
the observed penumbra was closely associated with flux emergence under
the pre-existing chromospheric canopy fields. Based on this finding,
we suggest a possible scenario for penumbra formation in which a
penumbra forms when the emerging flux is constrained from continuing
to emerge, but rather is trapped at the photospheric level by the
overlying chromospheric canopy fields.
Title: Comparison of Helicity Signs in Interplanetary CMEs and Their
Solar Source Regions
Authors: Cho, K. -S.; Park, S. -H.; Marubashi, K.; Gopalswamy, N.;
Akiyama, S.; Yashiro, S.; Kim, R. -S.; Lim, E. -K.
Bibcode: 2013SoPh..284..105C
Altcode:
If all coronal mass ejections (CMEs) have flux ropes, then the CMEs
should keep their helicity signs from the Sun to the Earth according to
the helicity conservation principle. This study presents an attempt to
answer the question from the Coordinated Data Analysis Workshop (CDAW),
"Do all CMEs have flux ropes?", by using a qualitative helicity sign
comparison between interplanetary CMEs (ICMEs) and their CME source
regions. For this, we select 34 CME-ICME pairs whose source active
regions (ARs) have continuous SOHO/MDI magnetogram data covering
more than 24 hr without data gap during the passage of the ARs near
the solar disk center. The helicity signs in the ARs are determined
by estimation of cumulative magnetic helicity injected through the
photosphere in the entire source ARs. The helicity signs in the ICMEs
are estimated by applying the cylinder model developed by Marubashi
(Adv. Space. Res., 26, 55, 2000) to 16 second resolution magnetic field
data from the MAG instrument onboard the ACE spacecraft. It is found
that 30 out of 34 events (88 %) are helicity sign-consistent events,
while four events (12 %) are sign-inconsistent. Through a detailed
investigation of the source ARs of the four sign-inconsistent events,
we find that those events can be explained by the local helicity
sign opposite to that of the entire AR helicity (28 July 2000 ICME),
incorrectly reported solar source region in the CDAW list (20 May 2005
ICME), or the helicity sign of the pre-existing coronal magnetic field
(13 October 2000 and 20 November 2003 ICMEs). We conclude that the
helicity signs of the ICMEs are quite consistent with those of the
injected helicities in the AR regions from where the CMEs erupted.
Title: Progress Report of Korean Data Center for SDO
Authors: Choi, S.; Hwang, E.; Baek, J. -H.; Kim, Y. -H.; Park, Y. -D.;
Cho, K. -S.
Bibcode: 2013enss.confE.136C
Altcode:
KASI has been constructing Korean Data Center for SDO based on the
letter of agreement between KASI and NASA for space weather research. We
have installed a data transfer server and a storage system about 1.5
PB. We have successfully installed NetDRMS to synchronize database and
JMD to download FITS files with the help of Stanford University and
NSO. We will increase its storage capacity more from year to year. In
2013, we will improve network performance and stability through GLORIAD
between Stanford University and KASI, and it will be integrated with
VSO (Virtual Solar Observatory). In addition, scientists and space
weather institutes will be able to access Korean data center through
the website (http://sdo.kasi.re.kr) and the visualization tool that is
in development and be scheduled to be released in the middle of this
year. The Korean Data Center for SDO will contribute space weather
researches and applications not only in Korea but also over the world.
Title: A High-frequency Type II Solar Radio Burst Associated with
the 2011 February 13 Coronal Mass Ejection
Authors: Cho, K. -S.; Gopalswamy, N.; Kwon, R. -Y.; Kim, R. -S.;
Yashiro, S.
Bibcode: 2013ApJ...765..148C
Altcode:
We examine the relationship between the high-frequency (425 MHz) type II
radio burst and the associated white-light coronal mass ejection (CME)
that occurred on 2011 February 13. The radio burst had a drift rate of
2.5 MHz s-1, indicating a relatively high shock speed. From
SDO/AIA observations we find that a loop-like erupting front sweeps
across high-density coronal loops near the start time of the burst
(17:34:17 UT). The deduced distance of shock formation (0.06 Rs)
from the flare center and speed of the shock (1100 km s-1)
using the measured density from SDO/AIA observations are comparable
to the height (0.05 Rs, from the solar surface) and speed (700 km
s-1) of the CME leading edge observed by STEREO/EUVI. We
conclude that the type II burst originates even in the low corona
(<59 Mm or 0.08 Rs, above the solar surface) due to the fast CME
shock passing through high-density loops.
Title: STEREO Observations of Fast Magnetosonic Waves in the Extended
Solar Corona Associated with EIT/EUV Waves
Authors: Kwon, Ryun-Young; Ofman, Leon; Olmedo, Oscar; Kramar, Maxim;
Davila, Joseph M.; Thompson, Barbara J.; Cho, Kyung-Suk
Bibcode: 2013ApJ...766...55K
Altcode:
We report white-light observations of a fast magnetosonic wave
associated with a coronal mass ejection observed by STEREO/SECCHI/COR1
inner coronagraphs on 2011 August 4. The wave front is observed in the
form of density compression passing through various coronal regions such
as quiet/active corona, coronal holes, and streamers. Together with
measured electron densities determined with STEREO COR1 and Extreme
UltraViolet Imager (EUVI) data, we use our kinematic measurements of
the wave front to calculate coronal magnetic fields and find that the
measured speeds are consistent with characteristic fast magnetosonic
speeds in the corona. In addition, the wave front turns out to be
the upper coronal counterpart of the EIT wave observed by STEREO
EUVI traveling against the solar coronal disk; moreover, stationary
fronts of the EIT wave are found to be located at the footpoints of
deflected streamers and boundaries of coronal holes, after the wave
front in the upper solar corona passes through open magnetic field
lines in the streamers. Our findings suggest that the observed EIT
wave should be in fact a fast magnetosonic shock/wave traveling in
the inhomogeneous solar corona, as part of the fast magnetosonic wave
propagating in the extended solar corona.
Title: Multiwavelength Study of a Solar Eruption from AR NOAA 11112
I. Flux Emergence, Sunspot Rotation and Triggering of a Solar Flare
Authors: Kumar, Pankaj; Park, Sung-Hong; Cho, K. -S.; Bong, S. -C.
Bibcode: 2013SoPh..282..503K
Altcode: 2012arXiv1210.3413K
We analyze the multiwavelength observations of an M2.9/1N flare
that occurred in the active region (AR) NOAA 11112 in the vicinity
of a huge filament system on 16 October 2010. SDO/HMI magnetograms
reveal the emergence of a bipole (within the existing AR) 50 hours
prior to the flare event. During the emergence, both the positive and
negative sunspots in the bipole show translational as well as rotational
motion. The positive-polarity sunspot shows significant motion/rotation
in the south-westward/clockwise direction, and we see continuously
pushing/sliding of the surrounding opposite-polarity field region. On
the other hand, the negative-polarity sunspot moves/rotates in the
westward/anticlockwise direction. The positive-polarity sunspot rotates
≈ 70∘ within 30 hours, whereas the one with negative
polarity rotates ≈ 20∘ within 10 hours. SDO/AIA 94 Å
EUV images show the emergence of a flux tube in the corona, consistent
with the emergence of the bipole in HMI. The footpoints of the flux
tube were anchored in the emerging bipole. The initial brightening
starts at one of the footpoints (western) of the emerging loop system,
where the positive-polarity sunspot pushes/slides towards a nearby
negative-polarity field region. A high speed plasmoid ejection (speed
≈ 1197 km s−1) was observed during the impulsive phase
of the flare, which suggests magnetic reconnection of the emerging
positive-polarity sunspot with the surrounding opposite-polarity
field region. The entire AR shows positive-helicity injection before
the flare event. Moreover, the newly emerging bipole reveals the
signature of a negative (left-handed) helicity. These observations
provide unique evidence of the emergence of twisted flux tubes from
below the photosphere to coronal heights, triggering a flare mainly
due to the interaction between the emerging positive-polarity sunspot
and a nearby negative-polarity sunspot by the shearing motion of the
emerging positive sunspot towards the negative one. Our observations
also strongly support the idea that the rotation can most likely be
attributed to the emergence of twisted magnetic fields, as proposed
by recent models.
Title: Multiwavelength Study of a Solar Eruption from AR NOAA 11112:
II. Large-Scale Coronal Wave and Loop Oscillation
Authors: Kumar, Pankaj; Cho, K. -S.; Chen, P. F.; Bong, S. -C.;
Park, Sung-Hong
Bibcode: 2013SoPh..282..523K
Altcode: 2012arXiv1210.3417K
We analyze multiwavelength observations of an M2.9/1N flare that
occurred in AR NOAA 11112 on 16 October 2010. AIA 211 Å EUV images
reveal the presence of a faster coronal wave (decelerating from ≈
1390 to ≈ 830 km s−1) propagating ahead of a slower wave
(decelerating from ≈ 416 to ≈ 166 km s−1) towards
the western limb. The dynamic radio spectrum from Sagamore Hill
radio telescope shows the presence of a metric type II radio burst,
which reveals the presence of a coronal shock wave (speed ≈ 800 km
s−1). The speed of the faster coronal wave, derived from
AIA 211 Å images, is found to be comparable to the coronal shock
speed. AIA 171 Å high-cadence observations showed that a coronal
loop, which was located at a distance of ≈ 0.32R⊙ to
the west of the flaring region, started to oscillate by the end of
the impulsive phase of the flare. The results indicate that the faster
coronal wave may be the first driver of the transversal oscillations
of coronal loop. As the slower wave passed through the coronal loop,
the oscillations became even stronger. There was a plasmoid eruption
observed in EUV and a white-light CME was recorded, having velocity of
≈ 340 - 350 km s−1. STEREO 195 Å images show an EIT
wave, propagating in the same direction as the lower-speed coronal
wave observed in AIA, but decelerating from ≈ 320 to ≈ 254 km
s−1. These observations reveal the co-existence of both
waves (i.e. coronal Moreton and EIT waves), and the type II radio
burst seems to be associated with the coronal Moreton wave.
Title: Multi-wavelength investigation of pre-flare activity and
magnetic reconnection during the evolutionary phases of a solar
eruptive flare
Authors: Joshi, Bhuwan; Veronig, Astrid; Cho, Kyung-Suk; Bong, Su-chan;
Tiwari, Sanjiv Kumar; Lee, J.
Bibcode: 2012cosp...39..845J
Altcode: 2012cosp.meet..845J
No abstract at ADS
Title: Day-to-day variability of equatorial anomaly in GPS-TEC during
low solar activity period
Authors: Aggarwal, Malini; Joshi, H. P.; Iyer, K. N.; Kwak, Y. -S.;
Lee, J. J.; Chandra, H.; Cho, K. S.
Bibcode: 2012AdSpR..49.1709A
Altcode:
The ionospheric total electron content (TEC) in the northern hemispheric
equatorial ionization anomaly (EIA) crest region is investigated by
using dual-frequency signals of the Global Positioning System (GPS)
acquired from Rajkot (Geog. Lat. 22.29°N, Geog. Long. 70.74°E;
Geom. Lat. 14.21°N, Geom. Long. 144.90°E), India. The day-to-day
variability of EIA characteristics is examined during low solar activity
period (F10.7∼83 sfu). It is found that the daily maximum TEC at EIA
crest exhibits a day-to-day and strong semi-annual variability. The
seasonal anomaly and equinoctial asymmetry in TEC at EIA is found
non-existent and weaker, respectively. We found a moderate and positive
correlation of daily magnitude of crest, Ic with daily F10.7 and EUV
fluxes with a correlation coefficient of 0.43 and 0.33, respectively
indicating an existence of a short-term relation between TEC at EIA
and the solar radiation even during low solar activity period. The
correlation of daily Ic with Dst index is also moderate (r = -0.35),
whereas no correlation is found with the daily Kp index (r = 0.14)
respectively. We found that the magnitude of EIA crest is moderately
correlated with solar flux in all seasons except winter where it is
weakly related (0.27). The magnitude of EIA crest is also found highly
related with EEJ strength in spring (r = 0.69) and summer (r = 0.65)
than autumn (0.5) and winter (r = 0.47), though EEJ is stronger in
autumn than spring.
Title: The Occurrence and Speed of CMEs Related to Two Characteristic
Evolution Patterns of Helicity Injection in Their Solar Source Regions
Authors: Park, Sung-Hong; Cho, Kyung-Suk; Bong, Su-Chan; Kumar,
Pankaj; Chae, Jongchul; Liu, Rui; Wang, Haimin
Bibcode: 2012ApJ...750...48P
Altcode: 2012arXiv1203.1690P
Long-term (a few days) variation of magnetic helicity injection
was calculated for 28 solar active regions that produced 47 coronal
mass ejections (CMEs) to find its relationship to the CME occurrence
and speed using SOHO/MDI line-of-sight magnetograms. As a result, we
found that the 47 CMEs can be categorized into two different groups by
two characteristic evolution patterns of helicity injection in their
source active regions, which appeared for ~0.5-4.5 days before their
occurrence: (1) a monotonically increasing pattern with one sign of
helicity (Group A 30 CMEs in 23 active regions) and (2) a pattern
of significant helicity injection followed by its sign reversal
(Group B 17 CMEs in 5 active regions). We also found that CME speed
has a correlation with average helicity injection rate with linear
correlation coefficients of 0.85 and 0.63 for Group A and Group B,
respectively. In addition, these two CME groups show different
characteristics as follows: (1) the average CME speed of Group B
(1330 km s-1) is much faster than that of Group A (870
km s-1), (2) the CMEs in Group A tend to be single events
whereas those in Group B mainly consist of successive events, and (3)
flares related to the CMEs in Group B are relatively more energetic
and impulsive than those in Group A. Our findings therefore suggest
that the two CME groups have different pre-CME conditions in their
source active regions and different CME characteristics.
Title: Search for a Dark Matter Candidate Produced in Association
with a Single Top Quark in pp¯ Collisions at s=1.96TeV
Authors: Aaltonen, T.; Álvarez González, B.; Amerio, S.; Amidei,
D.; Anastassov, A.; Annovi, A.; Antos, J.; Anzá, F.; Apollinari,
G.; Appel, J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas,
W.; Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.;
Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.;
Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini, G.;
Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bisello,
D.; Bizjak, I.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.;
Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg,
C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto,
G.; Bussey, P.; Buzatu, A.; Calamba, A.; Calancha, C.; Camarda, S.;
Campanelli, M.; Campbell, M.; Canelli, F.; Carls, B.; Carlsmith,
D.; Carosi, R.; Carrillo, S.; Carron, S.; Casal, B.; Casarsa, M.;
Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza,
M.; Cerri, A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.;
Chlachidze, G.; Chlebana, F.; Cho, K.; Chokheli, D.; Chung, W. H.;
Chung, Y. S.; Ciocci, M. A.; Clark, A.; Clarke, C.; Compostella,
G.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.;
Cox, D. J.; Crescioli, F.; Cuevas, J.; Culbertson, R.; Dagenhart, D.;
d'Ascenzo, N.; Datta, M.; de Barbaro, P.; Dell'Orso, M.; Demortier,
L.; Deninno, M.; Devoto, F.; d'Errico, M.; Di Canto, A.; Di Ruzza,
B.; Dittmann, J. R.; D'Onofrio, M.; Donati, S.; Dong, P.; Dorigo,
M.; Dorigo, T.; Ebina, K.; Elagin, A.; Eppig, A.; Erbacher, R.;
Errede, S.; Ershaidat, N.; Eusebi, R.; Farrington, S.; Feindt, M.;
Fernandez, J. P.; Field, R.; Flanagan, G.; Forrest, R.; Frank, M. J.;
Franklin, M.; Freeman, J. C.; Fuks, B.; Funakoshi, Y.; Furic, I.;
Gallinaro, M.; Garcia, J. E.; Garfinkel, A. F.; Garosi, P.; Gerberich,
H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Giannetti, P.;
Gibson, K.; Ginsburg, C. M.; Giokaris, N.; Giromini, P.; Giurgiu,
G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Goldschmidt,
N.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.;
González, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Grinstein,
S.; Grosso-Pilcher, C.; Group, R. C.; Guimaraes da Costa, J.; Hahn,
S. R.; Halkiadakis, E.; Hamaguchi, A.; Han, J. Y.; Happacher, F.; Hara,
K.; Hare, D.; Hare, M.; Harr, R. F.; Hatakeyama, K.; Hays, C.; Heck,
M.; Heinrich, J.; Herndon, M.; Hewamanage, S.; Hocker, A.; Hopkins,
W.; Horn, D.; Hou, S.; Hughes, R. E.; Hurwitz, M.; Husemann, U.;
Hussain, N.; Hussein, M.; Huston, J.; Introzzi, G.; Iori, M.; Ivanov,
A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jindariani, S.;
Jones, M.; Joo, K. K.; Jun, S. Y.; Junk, T. R.; Kamon, T.; Karchin,
P. E.; Kasmi, A.; Kato, Y.; Ketchum, W.; Keung, J.; Khotilovich, V.;
Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim,
S. B.; Kim, S. H.; Kim, Y. K.; Kim, Y. J.; Kimura, N.; Kirby, M.;
Klimenko, S.; Knoepfel, K.; Kondo, K.; Kong, D. J.; Konigsberg, J.;
Kotwal, A. V.; Kreps, M.; Kroll, J.; Krop, D.; Kruse, M.; Krutelyov,
V.; Kuhr, T.; Kurata, M.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel,
S.; Lancaster, M.; Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.;
LeCompte, T.; Lee, E.; Lee, H. S.; Lee, J. S.; Lee, S. W.; Leo, S.;
Leone, S.; Lewis, J. D.; Limosani, A.; Lin, C. -J.; Lindgren, M.;
Lipeles, E.; Lister, A.; Litvintsev, D. O.; Liu, C.; Liu, H.; Liu, Q.;
Liu, T.; Lockwitz, S.; Loginov, A.; Lucchesi, D.; Lueck, J.; Lujan,
P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; Madrak, R.; Maeshima,
K.; Maestro, P.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.;
Margaroli, F.; Marino, C.; Martínez, M.; Mastrandrea, P.; Matera,
K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McFarland, K. S.;
McIntyre, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Mesropian, C.;
Miao, T.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.;
Mondragon, M. N.; Moon, C. S.; Moore, R.; Morello, M. J.; Morlock, J.;
Movilla Fernandez, P.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini,
M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakano, I.; Napier, A.;
Nett, J.; Neu, C.; Neubauer, M. S.; Nielsen, J.; Nodulman, L.; Noh,
S. Y.; Norniella, O.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.;
Okusawa, T.; Orava, R.; Ortolan, L.; Pagan Griso, S.; Pagliarone,
C.; Palencia, E.; Papadimitriou, V.; Paramonov, A. A.; Patrick,
J.; Pauletta, G.; Paulini, M.; Paus, C.; Pellett, D. E.; Penzo, A.;
Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.;
Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos, K.; Prokoshin,
F.; Pranko, A.; Ptohos, F.; Punzi, G.; Rahaman, A.; Ramakrishnan,
V.; Ranjan, N.; Redondo, I.; Renton, P.; Rescigno, M.; Riddick, T.;
Rimondi, F.; Ristori, L.; Robson, A.; Rodrigo, T.; Rodriguez, T.;
Rogers, E.; Rolli, S.; Roser, R.; Ruffini, F.; Ruiz, A.; Russ, J.;
Rusu, V.; Safonov, A.; Sakumoto, W. K.; Sakurai, Y.; Santi, L.; Sato,
K.; Saveliev, V.; Savoy-Navarro, A.; Schlabach, P.; Schmidt, A.;
Schmidt, E. E.; Schwarz, T.; Scodellaro, L.; Scribano, A.; Scuri,
F.; Seidel, S.; Seiya, Y.; Semenov, A.; Sforza, F.; Shalhout,
S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shochet, M.;
Shreyber-Tecker, I.; Simonenko, A.; Sinervo, P.; Sliwa, K.; Smith,
J. R.; Snider, F. D.; Soha, A.; Sorin, V.; Song, H.; Squillacioti,
P.; Stancari, M.; St. Denis, R.; Stelzer, B.; Stelzer-Chilton, O.;
Stentz, D.; Strologas, J.; Strycker, G. L.; Sudo, Y.; Sukhanov, A.;
Suslov, I.; Takemasa, K.; Takeuchi, Y.; Tang, J.; Tecchio, M.; Teng,
P. K.; Thom, J.; Thome, J.; Thompson, G. A.; Thomson, E.; Toback,
D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.;
Torretta, D.; Totaro, P.; Trovato, M.; Ukegawa, F.; Uozumi, S.;
Varganov, A.; Vázquez, F.; Velev, G.; Vellidis, C.; Vidal, M.; Vila,
I.; Vilar, R.; Vizán, J.; Vogel, M.; Volpi, G.; Wagner, P.; Wagner,
R. L.; Wakisaka, T.; Wallny, R.; Wang, S. M.; Warburton, A.; Waters,
D.; Wester, W. C., III; Whiteson, D.; Wicklund, A. B.; Wicklund, E.;
Wilbur, S.; Wick, F.; Williams, H. H.; Wilson, J. S.; Wilson, P.;
Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, H.; Wright, T.; Wu,
X.; Wu, Z.; Yamamoto, K.; Yamato, D.; Yang, T.; Yang, U. K.; Yang,
Y. C.; Yao, W. -M.; Yeh, G. P.; Yi, K.; Yoh, J.; Yorita, K.; Yoshida,
T.; Yu, G. B.; Yu, I.; Yu, S. S.; Yun, J. C.; Zanetti, A.; Zeng, Y.;
Zhou, C.; Zucchelli, S.
Bibcode: 2012PhRvL.108t1802A
Altcode: 2012arXiv1202.5653C
We report a new search for dark matter in a data sample of an integrated
luminosity of 7.7fb-1 of Tevatron pp¯ collisions at
s=1.96TeV, collected by the CDF II detector. We search for production of
a dark-matter candidate, D, in association with a single top quark. We
consider the hadronic decay mode of the top quark exclusively, yielding
a final state of three jets with missing transverse energy. The data
are consistent with the standard model; we thus set 95% confidence
level upper limits on the cross section of the process pp¯→t+D as
a function of the mass of the dark-matter candidate. The limits are
approximately 0.5 pb for a dark-matter particle with mass in the range
of 0-150GeV/c2.
Title: Search for Dark Matter in Events with One Jet and Missing
Transverse Energy in pp¯ Collisions at s=1.96TeV
Authors: Aaltonen, T.; Álvarez González, B.; Amerio, S.; Amidei,
D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel,
J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.;
Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Bai,
Y.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria,
P.; Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini,
G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bisello,
D.; Bizjak, I.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.;
Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg,
C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto,
G.; Bussey, P.; Buzatu, A.; Calamba, A.; Calancha, C.; Camarda, S.;
Campanelli, M.; Campbell, M.; Canelli, F.; Carls, B.; Carlsmith, D.;
Carosi, R.; Carrillo, S.; Carron, S.; Casal, B.; Casarsa, M.; Castro,
A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri,
A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze,
G.; Chlebana, F.; Cho, K.; Chokheli, D.; Chung, W. H.; Chung, Y. S.;
Ciocci, M. A.; Clark, A.; Clarke, C.; Compostella, G.; Convery,
M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.;
Crescioli, F.; Cuevas, J.; Culbertson, R.; Dagenhart, D.; d'Ascenzo,
N.; Datta, M.; de Barbaro, P.; Dell'Orso, M.; Demortier, L.; Deninno,
M.; Devoto, F.; d'Errico, M.; Di Canto, A.; Di Ruzza, B.; Dittmann,
J. R.; D'Onofrio, M.; Donati, S.; Dong, P.; Dorigo, M.; Dorigo, T.;
Ebina, K.; Elagin, A.; Eppig, A.; Erbacher, R.; Errede, S.; Ershaidat,
N.; Eusebi, R.; Farrington, S.; Feindt, M.; Fernandez, J. P.; Field,
R.; Flanagan, G.; Forrest, R.; Fox, P. J.; Frank, M. J.; Franklin, M.;
Freeman, J. C.; Funakoshi, Y.; Furic, I.; Gallinaro, M.; Garcia, J. E.;
Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerchtein, E.; Giagu,
S.; Giakoumopoulou, V.; Giannetti, P.; Gibson, K.; Ginsburg, C. M.;
Giokaris, N.; Giromini, P.; Giurgiu, G.; Glagolev, V.; Glenzinski,
D.; Gold, M.; Goldin, D.; Goldschmidt, N.; Golossanov, A.; Gomez,
G.; Gomez-Ceballos, G.; Goncharov, M.; González, O.; Gorelov, I.;
Goshaw, A. T.; Goulianos, K.; Grinstein, S.; Grosso-Pilcher, C.; Group,
R. C.; Guimaraes da Costa, J.; Hahn, S. R.; Halkiadakis, E.; Hamaguchi,
A.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, D.; Hare, M.; Harnik,
R.; Harr, R. F.; Hatakeyama, K.; Hays, C.; Heck, M.; Heinrich, J.;
Herndon, M.; Hewamanage, S.; Hocker, A.; Hopkins, W.; Horn, D.; Hou,
S.; Hughes, R. E.; Hurwitz, M.; Husemann, U.; Hussain, N.; Hussein, M.;
Huston, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.;
Jayatilaka, B.; Jeon, E. J.; Jindariani, S.; Jones, M.; Joo, K. K.;
Jun, S. Y.; Junk, T. R.; Kamon, T.; Karchin, P. E.; Kasmi, A.; Kato,
Y.; Ketchum, W.; Keung, J.; Khotilovich, V.; Kilminster, B.; Kim,
D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.;
Kim, Y. K.; Kim, Y. J.; Kimura, N.; Kirby, M.; Klimenko, S.; Knoepfel,
K.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kreps,
M.; Kroll, J.; Krop, D.; Kruse, M.; Krutelyov, V.; Kuhr, T.; Kurata,
M.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lancaster, M.;
Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.; LeCompte, T.; Lee,
E.; Lee, H. S.; Lee, J. S.; Lee, S. W.; Leo, S.; Leone, S.; Lewis,
J. D.; Limosani, A.; Lin, C. -J.; Lindgren, M.; Lipeles, E.; Lister,
A.; Litvintsev, D. O.; Liu, C.; Liu, H.; Liu, Q.; Liu, T.; Lockwitz,
S.; Loginov, A.; Lucchesi, D.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu,
G.; Lys, J.; Lysak, R.; Madrak, R.; Maeshima, K.; Maestro, P.; Malik,
S.; Manca, G.; Manousakis-Katsikakis, A.; Margaroli, F.; Marino, C.;
Martínez, M.; Mastrandrea, P.; Matera, K.; Mattson, M. E.; Mazzacane,
A.; Mazzanti, P.; McFarland, K. S.; McIntyre, P.; McNulty, R.; Mehta,
A.; Mehtala, P.; Mesropian, C.; Miao, T.; Mietlicki, D.; Mitra, A.;
Miyake, H.; Moed, S.; Moggi, N.; Mondragon, M. N.; Moon, C. S.; Moore,
R.; Morello, M. J.; Morlock, J.; Movilla Fernandez, P.; Mukherjee,
A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.;
Naganoma, J.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Neubauer,
M. S.; Nielsen, J.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Oakes, L.;
Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Ortolan,
L.; Pagan Griso, S.; Pagliarone, C.; Palencia, E.; Papadimitriou,
V.; Paramonov, A. A.; Patrick, J.; Pauletta, G.; Paus, C.; Pellett,
D. E.; Penzo, A.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot,
J.; Pitts, K.; Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos,
K.; Prokoshin, F.; Pranko, A.; Ptohos, F.; Punzi, G.; Rahaman, A.;
Ramakrishnan, V.; Ranjan, N.; Redondo, I.; Renton, P.; Rescigno,
M.; Riddick, T.; Rimondi, F.; Ristori, L.; Robson, A.; Rodrigo, T.;
Rodriguez, T.; Rogers, E.; Rolli, S.; Roser, R.; Ruffini, F.; Ruiz,
A.; Russ, J.; Rusu, V.; Safonov, A.; Sakumoto, W. K.; Sakurai, Y.;
Santi, L.; Sato, K.; Saveliev, V.; Savoy-Navarro, A.; Schlabach, P.;
Schmidt, A.; Schmidt, E. E.; Schwarz, T.; Scodellaro, L.; Scribano, A.;
Scuri, F.; Seidel, S.; Seiya, Y.; Semenov, A.; Sforza, F.; Shalhout,
S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shochet, M.;
Shreyber-Tecker, I.; Simonenko, A.; Sinervo, P.; Sliwa, K.; Smith,
J. R.; Snider, F. D.; Soha, A.; Sorin, V.; Song, H.; Squillacioti,
P.; Stancari, M.; St. Denis, R.; Stelzer, B.; Stelzer-Chilton, O.;
Stentz, D.; Strologas, J.; Strycker, G. L.; Sudo, Y.; Sukhanov, A.;
Suslov, I.; Takemasa, K.; Takeuchi, Y.; Tang, J.; Tecchio, M.; Teng,
P. K.; Thom, J.; Thome, J.; Thompson, G. A.; Thomson, E.; Toback,
D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.;
Torretta, D.; Totaro, P.; Trovato, M.; Ukegawa, F.; Uozumi, S.;
Varganov, A.; Vázquez, F.; Velev, G.; Vellidis, C.; Vidal, M.; Vila,
I.; Vilar, R.; Vizán, J.; Vogel, M.; Volpi, G.; Wagner, P.; Wagner,
R. L.; Wakisaka, T.; Wallny, R.; Wang, S. M.; Warburton, A.; Waters,
D.; Wester, W. C., III; Whiteson, D.; Wicklund, A. B.; Wicklund, E.;
Wilbur, S.; Wick, F.; Williams, H. H.; Wilson, J. S.; Wilson, P.;
Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, H.; Wright, T.; Wu,
X.; Wu, Z.; Yamamoto, K.; Yamato, D.; Yang, T.; Yang, U. K.; Yang,
Y. C.; Yao, W. -M.; Yeh, G. P.; Yi, K.; Yoh, J.; Yorita, K.; Yoshida,
T.; Yu, G. B.; Yu, I.; Yu, S. S.; Yun, J. C.; Zanetti, A.; Zeng, Y.;
Zhou, C.; Zucchelli, S.
Bibcode: 2012PhRvL.108u1804A
Altcode: 2012arXiv1203.0742T
We present the results of a search for dark matter production
in the monojet signature. We analyze a sample of Tevatron pp¯
collisions at s=1.96TeV corresponding to an integrated luminosity of
6.7fb-1 recorded by the CDF II detector. In events with large
missing transverse energy and one energetic jet, we find good agreement
between the standard model prediction and the observed data. We set 90%
confidence level upper limits on the dark matter production rate. The
limits are translated into bounds on nucleon-dark matter scattering
rates which are competitive with current direct detection bounds on
spin-independent interaction below a dark matter candidate mass of
5GeV/c2, and on spin-dependent interactions up to masses
of 200GeV/c2.
Title: Search for anomalous production of multiple leptons in
association with W and Z bosons at CDF
Authors: Aaltonen, T.; Álvarez González, B.; Amerio, S.; Amidei, D.;
Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J. A.;
Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Auerbach, B.;
Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Barbaro-Galtieri, A.;
Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauce, M.;
Bedeschi, F.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin,
D.; Beretvas, A.; Bhatti, A.; Bisello, D.; Bizjak, I.; Bland, K. R.;
Blumenfeld, B.; Bocci, A.; Bodek, A.; Bortoletto, D.; Boudreau, J.;
Boveia, A.; Brigliadori, L.; Bromberg, C.; Brucken, E.; Budagov,
J.; Budd, H. S.; Burkett, K.; Busetto, G.; Bussey, P.; Buzatu, A.;
Calamba, A.; Calancha, C.; Camarda, S.; Campanelli, M.; Campbell,
M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.;
Carron, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz,
D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chen,
Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Chlebana, F.; Cho,
K.; Chokheli, D.; Chung, W. H.; Chung, Y. S.; Ciocci, M. A.; Clark,
A.; Clarke, C.; Compostella, G.; Convery, M. E.; Conway, J.; Corbo,
M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Crescioli, F.; Cuevas, J.;
Culbertson, R.; Dagenhart, D.; d'Ascenzo, N.; Datta, M.; de Barbaro,
P.; Dell'Orso, M.; Demortier, L.; Deninno, M.; Devoto, F.; d'Errico,
M.; Di Canto, A.; Di Ruzza, B.; Dittmann, J. R.; D'Onofrio, M.; Donati,
S.; Dong, P.; Dorigo, M.; Dorigo, T.; Ebina, K.; Elagin, A.; Eppig,
A.; Erbacher, R.; Errede, S.; Ershaidat, N.; Eusebi, R.; Farrington,
S.; Feindt, M.; Fernandez, J. P.; Field, R.; Flanagan, G.; Forrest, R.;
Frank, M. J.; Franklin, M.; Freeman, J. C.; Frisch, H.; Funakoshi, Y.;
Furic, I.; Gallinaro, M.; Garcia, J. E.; Garfinkel, A. F.; Garosi, P.;
Gerberich, H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Giannetti,
P.; Gibson, K.; Ginsburg, C. M.; Giokaris, N.; Giromini, P.; Giurgiu,
G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Goldschmidt,
N.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.;
González, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Grinstein,
S.; Grosso-Pilcher, C.; Group, R. C.; Guimaraes da Costa, J.; Hahn,
S. R.; Halkiadakis, E.; Hamaguchi, A.; Han, J. Y.; Happacher, F.; Hara,
K.; Hare, D.; Hare, M.; Harr, R. F.; Hatakeyama, K.; Hays, C.; Heck,
M.; Heinrich, J.; Herndon, M.; Hewamanage, S.; Hocker, A.; Hopkins,
W.; Horn, D.; Hou, S.; Hughes, R. E.; Hurwitz, M.; Husemann, U.;
Hussain, N.; Hussein, M.; Huston, J.; Introzzi, G.; Iori, M.; Ivanov,
A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jindariani, S.;
Jones, M.; Joo, K. K.; Jun, S. Y.; Junk, T. R.; Kamon, T.; Karchin,
P. E.; Kasmi, A.; Kato, Y.; Ketchum, W.; Keung, J.; Khotilovich, V.;
Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim,
S. B.; Kim, S. H.; Kim, Y. K.; Kim, Y. J.; Kimura, N.; Kirby, M.;
Klimenko, S.; Knoepfel, K.; Kondo, K.; Kong, D. J.; Konigsberg, J.;
Kotwal, A. V.; Kreps, M.; Kroll, J.; Krop, D.; Kruse, M.; Krutelyov,
V.; Kuhr, T.; Kurata, M.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel,
S.; Lancaster, M.; Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.;
LeCompte, T.; Lee, E.; Lee, H. S.; Lee, J. S.; Lee, S. W.; Leo, S.;
Leone, S.; Lewis, J. D.; Limosani, A.; Lin, C. -J.; Lindgren, M.;
Lipeles, E.; Lister, A.; Litvintsev, D. O.; Liu, C.; Liu, H.; Liu, Q.;
Liu, T.; Lockwitz, S.; Loginov, A.; Lucchesi, D.; Lueck, J.; Lujan,
P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; Madrak, R.; Maeshima,
K.; Maestro, P.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.;
Margaroli, F.; Marino, C.; Martínez, M.; Mastrandrea, P.; Matera,
K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McFarland, K. S.;
McIntyre, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Mesropian, C.;
Miao, T.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.;
Mondragon, M. N.; Moon, C. S.; Moore, R.; Morello, M. J.; Morlock, J.;
Movilla Fernandez, P.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini,
M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakano, I.; Napier, A.;
Nett, J.; Neu, C.; Neubauer, M. S.; Nielsen, J.; Nodulman, L.; Noh,
S. Y.; Norniella, O.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.;
Okusawa, T.; Orava, R.; Ortolan, L.; Pagan Griso, S.; Pagliarone,
C.; Palencia, E.; Papadimitriou, V.; Paramonov, A. A.; Patrick,
J.; Pauletta, G.; Paulini, M.; Paus, C.; Pellett, D. E.; Penzo, A.;
Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.;
Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos, K.; Prokoshin,
F.; Pranko, A.; Ptohos, F.; Punzi, G.; Rahaman, A.; Ramakrishnan,
V.; Ranjan, N.; Redondo, I.; Renton, P.; Rescigno, M.; Riddick, T.;
Rimondi, F.; Ristori, L.; Robson, A.; Rodrigo, T.; Rodriguez, T.;
Rogers, E.; Rolli, S.; Roser, R.; Ruffini, F.; Ruiz, A.; Russ, J.;
Rusu, V.; Safonov, A.; Sakumoto, W. K.; Sakurai, Y.; Santi, L.; Sato,
K.; Saveliev, V.; Savoy-Navarro, A.; Schlabach, P.; Schmidt, A.;
Schmidt, E. E.; Schwarz, T.; Scodellaro, L.; Scribano, A.; Scuri,
F.; Seidel, S.; Seiya, Y.; Semenov, A.; Sforza, F.; Shalhout,
S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shochet, M.;
Shreyber-Tecker, I.; Simonenko, A.; Sinervo, P.; Sliwa, K.; Smith,
J. R.; Snider, F. D.; Soha, A.; Sorin, V.; Song, H.; Squillacioti,
P.; Stancari, M.; St. Denis, R.; Stelzer, B.; Stelzer-Chilton, O.;
Stentz, D.; Strologas, J.; Strycker, G. L.; Sudo, Y.; Sukhanov, A.;
Suslov, I.; Takemasa, K.; Takeuchi, Y.; Tang, J.; Tecchio, M.; Teng,
P. K.; Thom, J.; Thome, J.; Thompson, G. A.; Thomson, E.; Toback,
D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.;
Torretta, D.; Totaro, P.; Trovato, M.; Ukegawa, F.; Uozumi, S.;
Varganov, A.; Vázquez, F.; Velev, G.; Vellidis, C.; Vidal, M.; Vila,
I.; Vilar, R.; Vizán, J.; Vogel, M.; Volpi, G.; Wagner, P.; Wagner,
R. L.; Wakisaka, T.; Wallny, R.; Wang, S. M.; Warburton, A.; Waters,
D.; Wester, W. C., III; Whiteson, D.; Wicklund, A. B.; Wicklund, E.;
Wilbur, S.; Wick, F.; Williams, H. H.; Wilson, J. S.; Wilson, P.;
Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, H.; Wright, T.; Wu,
X.; Wu, Z.; Yamamoto, K.; Yamato, D.; Yang, T.; Yang, U. K.; Yang,
Y. C.; Yao, W. -M.; Yeh, G. P.; Yi, K.; Yoh, J.; Yorita, K.; Yoshida,
T.; Yu, G. B.; Yu, I.; Yu, S. S.; Yun, J. C.; Zanetti, A.; Zeng, Y.;
Zucchelli, S.
Bibcode: 2012PhRvD..85i2001A
Altcode: 2012arXiv1202.1260T
This paper presents a search for anomalous production of multiple
low-energy leptons in association with a W or Z boson using events
collected at the CDF experiment corresponding to 5.1fb-1
of integrated luminosity. This search is sensitive to a wide range
of topologies with low-momentum leptons, including those with
the leptons near one another. The observed rates of production of
additional electrons and muons are compared with the standard model
predictions. No indications of phenomena beyond the standard model are
found. A 95% confidence level limit is presented on the production cross
section for a benchmark model of supersymmetric hidden-valley Higgs
production. Particle identification efficiencies are also provided to
enable the calculation of limits on additional models.
Title: On the Relationship Between a High-frequency Type II Solar
Radio Burst and Coronal Mass Ejection on February 13, 2011
Authors: Cho, Kyung-Suk; Gopalswamy, N.; Kwon, R.; Kim, R.; Yashiro, S.
Bibcode: 2012AAS...22052502C
Altcode:
We examine the relationship between a metric type II radio burst that
started from an unusually high frequency of 425 MHz (fundamental
component) and the associated white-light coronal mass ejection on
2011 February 11. The radio burst had a drift rate of 3 MHz/sec,
indicating a relatively high shock speed. The question we would like
to answer is whether the high frequency type II burst is generated by
the CME. To avoid the ambiguity normally caused by the use of density
models in the analysis of type II bursts, we measure the coronal
electron density by applying automated emission measure analysis code
developed by Aschwanden et al. (2011) to AIA/SDO images in 6 coronal
filters. From SDO AIA observations we find that a loop-like erupting
front sweeps across high density coronal loops near the start time of
the burst (17:34:15 UT). The deduced height of shock formation (1.2
Rs) from the measured density is comparable to the height (1.15 Rs)
of the CME observed by STEREO/EUVI. Thus we conclude that the high
frequency type II burst could be generated at locations where the CME
passes through the high density loops in the low corona.
Title: Propagation Characteristics of CMEs Associated Magnetic Clouds
and Ejecta
Authors: Kim, Roksoon; Gopalswamy, N.; Cho, K.; Moon, Y.; Yashiro, S.
Bibcode: 2012AAS...22052108K
Altcode:
We have investigated the characteristics of magnetic cloud (MC)
and ejecta (EJ) associated coronal mass ejections (CMEs) based on
the assumption that all CMEs have a flux rope structure. For this,
we used 54 CMEs and their interplanetary counter parts (interplanetary
CMEs: ICMEs) that constitute the list of events used by the NASA/LWS
Coordinated Data Analysis Workshop (CDAW) on CME flux ropes. We
considered the location, angular width, speed, and direction parameter,
D, that quantifies the propagation direction of a CME. For the 54
CDAW events, we found several properties of the CMEs as follows:
(1) the average value of D for the 23 MCs (0.62) is larger than that
for the 31 EJs (0.49), which indicates that the MC-associated CMEs
propagate more directly to the Earth than the EJ-associated CMEs; (2)
comparison between the direction parameter and the source location
shows that the majority of the MC-associated CMEs are ejected along
the radial direction, while many of the EJ-associated CMEs are ejected
non-radially; (3) the mean speed of MC-associated CMEs (946 km/s)
is faster than that of EJ-associated CMEs (771 km/s). For seven
very fast CMEs (> 1500 km/s), all CMEs with large D (> 0.4)
are associated with MCs and the CMEs with small D are associated with
EJs. On the basis of these results, we suggest that the CME trajectory
essentially decides the observed ICME structure.
Title: Comparison of the bubble and blob distributions during the
solar minimum
Authors: Choi, H. -S.; Kil, H.; Kwak, Y. -S.; Park, Y. -D.; Cho, K. -S.
Bibcode: 2012JGRA..117.4314C
Altcode: 2012JGRA..11704314C
Plasma blobs, local plasma density enhancements with respect to the
background, in low to middle latitudes are understood as byproducts
of equatorial plasma bubbles, but this hypothesis is challenged by
observations of blobs in the absence of equatorial bubbles in the same
magnetic meridian. This study investigates the causal linkage between
bubbles and blobs using their occurrence statistics during the solar
minimum. The bubble and blob distributions were obtained by analyzing
the ion density data acquired during the period August 2008-April 2010
by the Coupled Ion-Neutral Dynamics Investigation instrument on board
the Communication/Navigation Outage Forecasting System satellite. The
seasonal, longitudinal, and latitudinal distributions of bubbles
during the solar minimum are similar to those during other periods of
the solar cycle. The distinctive bubble distribution during the solar
minimum is the high occurrence rate of bubbles after midnight. The
blob distribution shows the peak occurrence rate near midnight in the
altitude range 400-450 km and around ±25° magnetic latitudes. The
bubble occurrence rate is minimal during the June solstice, but the
blob occurrence rate is maximal during that season. The blob occurrence
rate has a peak value at about a 1700 km magnetic apex height, where
the bubble occurrence rate is negligibly small. The difference in
the bubble and blob distributions and the frequent occurrence of
blobs beyond the bubble apex height suggest that bubbles are not a
prerequisite for the creation of blobs.
Title: Magnetic Field Strength in the Upper Solar Corona Using
White-light Shock Structures Surrounding Coronal Mass Ejections
Authors: Kim, R. -S.; Gopalswamy, N.; Moon, Y. -J.; Cho, K. -S.;
Yashiro, S.
Bibcode: 2012ApJ...746..118K
Altcode: 2011arXiv1112.0288K
To measure the magnetic field strength in the solar corona,
we examined 10 fast (>=1000 km s-1) limb coronal
mass ejections(CMEs) that show clear shock structures in Solar and
Heliospheric Observatory/Large Angle and Spectrometric Coronagraph
images. By applying the piston-shock relationship to the observed
CME's standoff distance and electron density compression ratio, we
estimated the Mach number, Alfvén speed, and magnetic field strength
in the height range 3-15 solar radii (Rs ). The main results
from this study are as follows: (1) the standoff distance observed in
the solar corona is consistent with those from a magnetohydrodynamic
model and near-Earth observations; (2) the Mach number as a shock
strength is in the range 1.49-3.43 from the standoff distance ratio,
but when we use the density compression ratio, the Mach number is in
the range 1.47-1.90, implying that the measured density compression
ratio is likely to be underestimated owing to observational limits;
(3) the Alfvén speed ranges from 259 to 982 km s-1 and
the magnetic field strength is in the range 6-105 mG when the standoff
distance is used; (4) if we multiply the density compression ratio by
a factor of two, the Alfvén speeds and the magnetic field strengths
are consistent in both methods; and (5) the magnetic field strengths
derived from the shock parameters are similar to those of empirical
models and previous estimates.
Title: Initiation of Coronal Mass Ejection and Associated Flare
Caused by Helical Kink Instability Observed by SDO/AIA
Authors: Kumar, Pankaj; Cho, K. -S.; Bong, S. -C.; Park, Sung-Hong;
Kim, Y. H.
Bibcode: 2012ApJ...746...67K
Altcode: 2011arXiv1111.4360K
In this paper, we present multiwavelength observations of helical
kink instability as a trigger of a coronal mass ejection (CME) which
occurred in active region NOAA 11163 on 2011 February 24. The CME
was associated with an M3.5 limb flare. High-resolution observations
from the Solar Dynamics Observatory/Atmospheric Imaging Assembly
suggest the development of helical kink instability in the erupting
prominence, which implies a flux rope structure of the magnetic
field. A brightening starts below the apex of the prominence with
its slow rising motion (~100 km s-1) during the activation
phase. A bright structure, indicative of a helix with ~3-4 turns, was
transiently formed at this position. The corresponding twist of ~6π-8π
is sufficient to generate the helical kink instability in a flux rope
according to recently developed models. A slowly rising blob structure
was subsequently formed at the apex of the prominence, and a flaring
loop was observed near the footpoints. Within 2 minutes, a second blob
was formed in the northern prominence leg. The second blob erupts (like
a plasmoid ejection) with the detachment of the northern prominence
leg, and flare intensity maximizes. The first blob at the prominence
apex shows rotational motion in the counterclockwise direction in the
plane of sky, interpreted as the unwinding motion of a helix, and it
also erupts to give the CME. RHESSI hard X-ray (HXR) sources show the
two footpoint sources and a loop-top source during the flare. We found
RHESSI HXR flux, soft X-ray flux derivative, and CME acceleration in
the low corona correlate well, which is in agreement with the standard
flare model (CSHKP). We also discuss the possible role of ballooning
as well as torus instabilities in driving the CME. We conclude that
the CME and flare were triggered by the helical kink instability in
a flux rope and accelerated mainly by the torus instability.
Title: Geometry of the 20 November 2003 magnetic cloud
Authors: Marubashi, Katsuhide; Cho, Kyung-Suk; Kim, Yeon-Han; Park,
Yong-Deuk; Park, Sung-Hong
Bibcode: 2012JGRA..117.1101M
Altcode: 2012JGRA..11701101M
This study is an attempt to find a coherent interpretation of the
link between the 20 November 2003 magnetic cloud (MC) and its solar
source. Most previous studies agree on the orientation of the MC, but
the orientation is nearly perpendicular to the axis of the post-eruption
arcade (PEA) or the orientation of the neutral line in the solar source
region. We first determine the geometry of this MC by fitting methods
with both torus and cylinder models. Three possible geometries are
obtained, which can reproduce the observed magnetic field variations
associated with the MC, one from the cylinder fit and two from the torus
fit. The cylinder fit gives the MC orientation with a tilt of a large
angle (∼60°) from the ecliptic plane and nearly perpendicular to the
PEA axis, being similar to those from previous studies. In contrast,
two torus fit results give the MC axis with tilt angles less than
20° from the ecliptic plane. The two torus results correspond to
the spacecraft encounter with the eastern flank of the flux rope loop
(model A) and the western flank of the loop (model B), respectively. In
either case, the orientation of the loop around the apex is nearly
parallel to the PEA as observed by the SOHO/extreme ultraviolet imaging
telescope instrument in the most plausible solar source region of a
halo coronal mass ejection (CME), which appeared in the field of view
of Large Angle and Spectrometric Coronagraph (LASCO) C2 at 08:50 UT,
18 November 2003. The magnetic helicity of the PEA region is positive
in agreement with the helicity of the MC. The 3-D reconstruction from
the Solar Mass Ejection Imager data shows that the main part of the
ejected plasma expands mainly to the west of the Sun-Earth line. Thus,
we reach the most straightforward interpretation of the link between the
MC and its solar source as follows. The MC was created in association
with the launch of the CME that was first observed by the LASCO C2 at
08:50 UT, 18 November 2003, and propagated through interplanetary space
with its orientation almost unchanged. The spacecraft encountered the
eastern flank of the loop as described by model A.
Title: Comparison of helicity signs in magnetic clouds and their
solar source regions
Authors: Cho, K.; Park, S.; Marubashi, K.; Bong, S.; Kim, R.
Bibcode: 2011AGUFMSH51A1993C
Altcode:
Magnetic helicity, which is known as one of the few quantities that
are conserved, quantifies the signed amount of twists, kinks, and
inter-linkages of the magnetic field lines in a given magnetic field
system. CMEs are one of the means by which the Sun ejects magnetic
helicity into interplanetary space, and magnetic clouds (MCs) detected
near the Earth may carry a similar amount of helicity ejected from solar
source regions. If the helicity ejected by solar eruptions is conserved
from the Sun to the Earth, we can assume that flux ropes in MCs should
have similar characteristics with those in their solar source regions,
and it is also expected that the signs of their helicties on the Sun
and near the Earth should be same. With this expectation, we selected
36 CMEs that occurred at solar disk center among well identified 59
CME-MC pairs in the CDAW list, and determined the helicity signs in
magnetic clouds and their solar source regions, respectively. The
helicity signs in the solar source regions are determined by the
amount of helicity injection through their photospheric surfaces using
SOHO/MDI magnetograms, and the helicity signs in the MCs are estimated
by adopting cylinder and torus models to ACE solar wind data. As a
results, we found that among the total of 36 events, there are 30
helicity sign-consistent events (83%) and 6 sign-inconsistent events
(17%). This result shows that most flux ropes erupted from the surface
maintain their helicity signs from the Sun to the Earth, and supports
that flux ropes in the MCs have a similar characteristic with those in
their solar source regions. For 6 exceptional events, we investigate
them in detail if they do not follow the helicity conservation rule or
if they are come from the followings: (1) the helicity sign difference
between the entire source active region and the local CME-originated
region, (2) the wrong estimation of MC helicity signs by the fitting
models, or (3) the uncertainty of helicity sign determination in the
source region due to pre-existing opposite-sign helicity in a coronal
volume of the source region. In this talk, we will show that our results
support the idea of the helicity conservation rule of CDAW CME-MC pairs.
Title: Pre-flare Activity and Magnetic Reconnection during the
Evolutionary Stages of Energy Release in a Solar Eruptive Flare
Authors: Joshi, Bhuwan; Veronig, Astrid M.; Lee, Jeongwoo; Bong,
Su-Chan; Tiwari, Sanjiv Kumar; Cho, Kyung-Suk
Bibcode: 2011ApJ...743..195J
Altcode: 2011arXiv1109.3415J
In this paper, we present a multi-wavelength analysis of an eruptive
white-light M3.2 flare that occurred in active region NOAA 10486 on
2003 November 1. The excellent set of high-resolution observations
made by RHESSI and the TRACE provides clear evidence of significant
pre-flare activities for ~9 minutes in the form of an initiation
phase observed at EUV/UV wavelengths followed by an X-ray precursor
phase. During the initiation phase, we observed localized brightenings
in the highly sheared core region close to the filament and interactions
among short EUV loops overlying the filament, which led to the opening
of magnetic field lines. The X-ray precursor phase is manifested in
RHESSI measurements below ~30 keV and coincided with the beginning of
flux emergence at the flaring location along with early signatures of
the eruption. The RHESSI observations reveal that both plasma heating
and electron acceleration occurred during the precursor phase. The main
flare is consistent with the standard flare model. However, after the
impulsive phase, an intense hard X-ray (HXR) looptop source was observed
without significant footpoint emission. More intriguingly, for a brief
period, the looptop source exhibited strong HXR emission with energies
up to ~50-100 keV and significant non-thermal characteristics. The
present study indicates a causal relation between the activities in
the pre-flare and the main flare. We also conclude that pre-flare
activities, occurring in the form of subtle magnetic reorganization
along with localized magnetic reconnection, played a crucial role in
destabilizing the active region filament, leading to a solar eruptive
flare and associated large-scale phenomena.
Title: Magnetic field strength in the upper solar corona using
white-light shock structures surrounding coronal mass ejections
Authors: Kim, R.; Gopalswamy, N.; Moon, Y.; Cho, K.; Yashiro, S.
Bibcode: 2011AGUFMSH43B1955K
Altcode:
To measure the magnetic field strength in the solar corona, we examined
12 fast (> 1000 km s-1) limb CMEs which show clear shock-like
structures in SOHO/LASCO observations. By applying piston-shock
relationship to the observed CME's standoff distance and electron
density compression ratio, we estimated the Mach number, Alfven speed,
and magnetic field strength in the height range 3 to 15 solar radii
(Rs). We found: (1) the standoff distance observed in the solar corona
is consistent with those from a magnetohydrodynamic (MHD) model and
near-Earth observations; (2) the Mach number as a shock strength is
in the range 1.49 to 3.52 from the standoff distance data, but when
we use the compression ratio, the Mach number is in the range 1.47 to
1.90, implying that the measured density compression ratio is likely
to be underestimated due to observational limit; (3) the Alfven speed
ranges from 259 to 982 km s-1 and the magnetic field strength is in
the range 6 to 120 mG when the standoff distance is used; (4) if we
multiply the density compression ratio by a factor of 2, the Alfven
speeds and the magnetic field strengths are consistent in both methods;
(5) the magnetic field strengths derived from the shock parameters are
similar to those of empirical models and previous estimates. This is a
new attempt to measure magnetic field strength in the upper corona up
to 15 Rs from coronagraph observations alone. Our observations support
the idea that the diffuse structures surrounding the CME front can be
interpreted as shock structures.
Title: Dependence of GCRs influx on the solar North-South asymmetry
Authors: Cho, Il-Hyun; Kwak, Young-Sil; Chang, Heon-Young; Cho,
Kyung-Suk; Park, Young-Deuk; Choi, Ho-Sung
Bibcode: 2011JASTP..73.1723C
Altcode: 2011arXiv1103.4255C
We investigate the dependence of the amount of the observed galactic
cosmic ray (GCR) influx on the solar North-South asymmetry using the
neutron count rates obtained from four stations and sunspot data
in archives spanning five solar cycles from 1953 to 2008. We find
that the observed GCR influxes at Moscow, Kiel, Climax and Huancayo
stations are more suppressed when the solar activity in the southern
hemisphere is dominant compared with when the solar activity in the
northern hemisphere is dominant. Its reduction rates at four stations
are all larger than those of the suppression due to other factors
including the solar polarity effect on the GCR influx. We perform the
student's t-test to see how significant these suppressions are. It
is found that suppressions due to the solar North-South asymmetry as
well as the solar polarity are significant and yet the suppressions
associated with the former are larger and more significant.
Title: Two Types of Extreme-ultraviolet Brightenings In AR 10926
Observed by Hinode/EIS
Authors: Lee, K. -S.; Moon, Y. -J.; Kim, Sujin; Choe, G. S.; Cho,
Kyung-Suk; Imada, S.
Bibcode: 2011ApJ...736...15L
Altcode:
We have investigated seven extreme-ultraviolet (EUV) brightenings in the
active region AR 10926 on 2006 December 2 observed by the EUV Imaging
Spectrometer on board the Hinode spacecraft. We have determined their
Doppler velocities and non-thermal velocities from 15 EUV spectral
lines (log T = 4.7 - 6.4) by fitting each line profile to a Gaussian
function. The Doppler velocity maps for different temperatures are
presented to show the height dependence of the Doppler shifts. It is
found that the active region brightenings show two distinct Doppler
shift patterns. The type 1 brightening shows a systematic increase
of Doppler velocity from -68 km s-1 (strong blueshift) at
log T = 4.7 to -2 km s-1 (weak blueshift) at log T = 6.4,
while the type 2 brightenings have Doppler velocities in the range from
-20 km s-1 to 20 km s-1. The type 1 brightening
point is considered to sit in an upward reconnection outflow whose speed
decreases with height. In both types of brightenings, the non-thermal
velocity is found to be significantly enhanced at log T = 5.8 compared
to the background region. We have also determined electron densities
from line ratios and derived temperatures from emission measure loci
using the CHIANTI atomic database. The electron densities of all
brightenings are comparable to typical values in active regions (log
Ne = 9.9-10.4). The emission measure loci plots indicate
that these brightenings should be multi-thermal whereas the background
is isothermal. The differential emission measure as a function of
temperature shows multiple peaks in the EUV brightening regions, while
it has only a single peak (log T = 6.0) in the background region. Using
Michelson Doppler Imager magnetograms, we have found that the type 1
brightening is associated with a canceling magnetic feature with a flux
canceling rate of 2.4 × 1018 Mx hr-1. We also
found the canceling magnetic feature and chromospheric brightenings
in the type 1 brightening from the Hinode SOT and Transition Region
and Coronal Explorer data. This observation corroborates our argument
that brightening is caused by magnetic reconnection in a low atmosphere.
Title: An Analytical Model for the Coronal Component of Major Solar
Energetic Particle Events
Authors: Kocharov, Leon; Cho, Kyung-Suk; Valtonen, Eino
Bibcode: 2011ApJ...735....4K
Altcode:
We formulate an analytical model of the coronal-phase acceleration
observed in the beginning of major solar energetic particle (SEP)
events, before the main-phase acceleration associated with coronal mass
ejections (CMEs) in solar wind. The model is driven and constrained
by the broadband observations of SEPs and CMEs, in particular SEP
data from the particle telescope of the Energetic and Relativistic
Nuclei and Electron (ERNE) experiment on the Solar and Heliospheric
Observatory (SOHO) spacecraft, solar radio spectrograms, and low-corona
observations of CMEs. The model is also verified against observations
of solar high-energy neutrons and neutron-decay protons. The model
suggests SEP acceleration above ~ 50 MeV nucleon-1 by
coronal shock and the shock-amplified turbulence in closed magnetic
structures, and particle release at magnetic reconnection between the
closed structure of expanding CME and pre-existing open magnetic flux
tubes. The analytical model connects parameters of coronal shocks and
structures and the SEP parameters in space, which facilitates analysis
of multiwavelength data and will assist in further development of
coronal acceleration models.
Title: Relationship between multiple type II solar radio bursts and
CME observed by STEREO/SECCHI
Authors: Cho, K. -S.; Bong, S. -C.; Moon, Y. -J.; Shanmugaraju, A.;
Kwon, R. -Y.; Park, Y. D.
Bibcode: 2011A&A...530A..16C
Altcode:
Aims: Two or more type II bursts are occasionally observed
in close time sequence during solar eruptions, which are known as
multiple type II bursts. The origin of the successive burst has
been interpreted in terms of coronal mass ejections (CMEs) and/or
flares. Detailed investigations of the relationship between CMEs and
the bursts enable us to understand the nature of the multiple type II
bursts. In this study, we examine multiple type II bursts and compare
their kinematics with those of a CME occurring near the time of the
bursts.
Methods: To do this, we selected multiple type II bursts
observed by the Culgoora radiospectrographs and a limb CME detected in
the low corona field of view (1.4-4 Rs) of a STEREO/SECCHI
instrument on December 31, 2007. To determine the 3D kinematics of
the CME, we applied the stereoscopic technique to the STEREO/SECCHI
data.
Results: Our main results are as follows: (1) the multiple
type II bursts occurred successively at ten minute intervals and
displayed various emission structures and frequency drifting rates;
(2) near the time of the bursts, the CME was observed by STEREO and
SOHO simultaneously, but no evidence of other CMEs was detected;
(3) inspection of the 3D kinematics of the CME using the stereoscopic
observation by STEREO/SECCHI revealed that the CME propagated along the
eastward radial direction as viewed from the Earth; (4) very close time
and height associations were found between the CME nose and the first
type II burst, and between CME-streamer interaction and the second
type II burst.
Conclusions: On the basis of these results,
we suggest that a single shock in the leading edge of the CME could
be the source of the multiple type II bursts and support the notion
that the CME nose and the CME-streamer interaction are the two main
mechanisms able to generate the bursts.
Title: Magnetic Field Strength in the Upper Solar Corona Using
White-light Shock Structures Surrounding Coronal Mass Ejections
Authors: Kim, Roksoon; Gopalswamy, N.; Moon, Y.; Cho, K.; Yashiro, S.
Bibcode: 2011SPD....42.2306K
Altcode: 2011BAAS..43S.2306K
To measure the magnetic field strength in the solar corona, we examined
12 fast (> 1000 km s-1) limb CMEs which show clear shock-like
structures in SOHO/LASCO observations. By applying piston-shock
relationship to the observed CME's standoff distance and electron
density compression ratio, we estimated the Mach number, Alfven speed,
and magnetic field strength in the height range 3 to 15Rs. Main
results from this study are: (1) the standoff distance observed in
the solar corona is consistent with those from a magnetohydrodynamic
(MHD) model and near-Earth observations; (2) the Mach number as a shock
strength is in the range 1.49 to 3.52 from the standoff distance data,
but when we use the compression ratio, the Mach number is in the
range 1.47 to 1.90, implying that the measured density compression
ratio is likely to be underestimated due to projection effects; (3)
the Alfven speeds range from 259 to 982 km s-1 and the magnetic field
strength is in the range 0.04 to 0.35 G when the standoff distance
is used; (4) if we multiply the compression ratio by a factor of 2,
the Alfven speeds and the magnetic field strengths are consistent in
both methods; (5) the derived magnetic field strengths in the inner
corona are similar to those of empirical models but noticeably higher
in the upper corona. This is a new attempt to measure magnetic field
strength from coronagraph observation alone. These observations are
consistent with the idea that the diffuse structures surrounding the
CME front can be interpreted as shock structures.
Title: Propagating Transverse Wave In A Spicule Observed By The
Hinode Sot
Authors: Kim, Yeon-Han; Bong, S.; Cho, K.; Park, Y.; Cho, I.; Chae, J.
Bibcode: 2011SPD....42.0306K
Altcode: 2011BAAS..43S.0306K
We examined the wave signatures in a spicule observed by the Hinode SOT
to present a quantitative and clear evidence of propagating transverse
waves. Especially, we estimated the propagation wave speed in the
spicule observed on 2008 June 3 in the north polar limb of the Sun. For
this, we made time-slice stacks at different height of the spicule axis
using time series images of the spicule. All time-slice stacks for 9
different heights show oscillation patterns with a period of about 130
s. We also investigated the cross-correlation among time-slice stacks
to estimate the phase difference of the oscillation with height and
its propagating speed. We found that the mean phase delay over the
height difference of 3000 km is about 13 s. This result suggests that
the oscillation is a propagating transverse wave and the propagating
speed is about 220 km s-1. In addition, we found that the
estimated speeds increased from 100 to 230 km s-1 over 5000
km height range and this is well explained by the density variation
along the spicule structure.
Title: Study of Magnetic Helicity Injection in the Active Region
NOAA 11158 Associated with the X-class Flare of 2011 February 15
Authors: Park, Sung-Hong; Cho, K.; Kim, Y.; Bong, S.; Gary, D. E.;
Park, Y.
Bibcode: 2011SPD....42.2227P
Altcode: 2011BAAS..43S.2227P
The main objective of this study is to examine a long-term (a few
days) precondition and a trigger mechanism for an X2.2 flare peaking
at 01:56 UT on 2011 February 15 in GOES soft X-ray flux. For this,
we investigated the variation of magnetic helicity injection through
the photospheric surface of the flare-productive active region NOAA
11158 during (1) the long-term period of February 11 to 15 with a
1-hour cadence and (2) the short-term period of 01:26 to 02:10 UT
on February 15 with a 45-second cadence. The helicity injection was
determined using line-of-sight magnetograms with high spatial and
temporal resolution taken by the Helioseismic and Magnetic Imager
(HMI) onboard the Solar Dynamics Observatory (SDO). As a result, we
found two characteristic phases of helicity injection related to the
X2.2 flare. A large amount of positive helicity was first injected
over 2 days with a phase of monotonically increasing helicity. And
then the flare started simultaneously with a significant injection of
the opposite (negative) sign of helicity around the flaring magnetic
polarity inversion line. This observational finding clearly supports
the previous studies that there is a continuous injection of helicity
a few days before flares and a rapid injection of the helicity in the
opposite sign into an existing helicity system triggers flares.
Title: On the relationship between ground level enhancement and
solar flare
Authors: Firoz, K. A.; Moon, Y. -J.; Cho, K. -S.; Hwang, J.; Park,
Y. D.; Kudela, K.; Dorman, L. I.
Bibcode: 2011JGRA..116.4101F
Altcode:
We made an effort to understand the associations and relationships
between ground level enhancement (GLE) events and solar flares for
the time period of 1986-2006. Our results show that, on average,
the GLE event-associated solar flare (∼0.2 × 10-4
W/m2) is much stronger than the non-GLE-associated solar
flare (∼0.3 × 10-5 W/m2). The findings have
also been supported by the solar flare indices that, on average,
the GLE event-associated solar flare index (∼35.01) is much higher
than the non-GLE-associated solar flare index (∼4.88). However,
this association does not seem to precisely imply that GLEs can occur
because of a solar flare, so we examined cross correlations between
GLE events and simultaneous solar flares. We found that most (∼78%)
of the highest correlations (r > 0.8) took place during an X class
flare. There is no clear indication that the more the time lag, the
less or more is the correlation or vice versa. Overall, 50% of the high
correlations took place at higher time lag (≥65 min), and ∼36%
of the high correlations took place at lower time lag (≤40 min),
while the rest (∼14%) of the correlations were abruptly high and
low at medium time lag (>40 and <65 min). On the basis of the
results of cross correlations, we suggest that the intensive portions
of solar flares should be responsible for causing GLEs and that the
direct proportionality of the time-integrated intensive portion of
a flare with the impulsive phase of a GLE event seems to be the main
property for comprehending the mechanism.
Title: Development of the Fast Imaging Solar Spectrograph for 1.6
m New Solar Telescope
Authors: Nah, Ja-Kyoung; Chae, Jong-Chul; Park, Young-Deuk; Park,
Hyung-Min; Jang, Bi-Ho; Ahn, Kwang-Su; Yang, Hee-Su; Cho, Kyung-Suk;
Kim, Yeon-Han; Kim, Kwang-Dong; Cao, Wenda; Gorceix, Nicolas; Goode,
Philip. R.
Bibcode: 2011PKAS...26...45N
Altcode:
No abstract at ADS
Title: Recent activities of solar astronomers in Korea
Authors: Cho, K. -S.; Chae, J.; Moon, Y. J.; Choe, G. S.
Bibcode: 2011ASInC...2..383C
Altcode:
At present, about twenty PhDs are carrying out education, research, and
observation in the field of solar astronomy in Korea. The history and
recent activities of the Korean solar community are briefly reviewed
in this paper. We expect that the current efforts of Korean solar
astronomers contribute to the promotion of cooperative solar research
in the Asian-Pacific countries.
Title: An empirical model for prediction of geomagnetic storms using
initially observed CME parameters at the Sun
Authors: Kim, R. -S.; Cho, K. -S.; Moon, Y. -J.; Dryer, M.; Lee, J.;
Yi, Y.; Kim, K. -H.; Wang, H.; Park, Y. -D.; Kim, Yong Ha
Bibcode: 2010JGRA..11512108K
Altcode:
In this study, we discuss the general behaviors of geomagnetic storm
strength associated with observed parameters of coronal mass ejection
(CME) such as speed (V) and earthward direction (D) of CMEs as well
as the longitude (L) and magnetic field orientation (M) of overlaying
potential fields of the CME source region, and we develop an empirical
model to predict geomagnetic storm occurrence with its strength (gauged
by the Dst index) in terms of these CME parameters. For this we select
66 halo or partial halo CMEs associated with M-class and X-class solar
flares, which have clearly identifiable source regions, from 1997 to
2003. After examining how each of these CME parameters correlates
with the geoeffectiveness of the CMEs, we find several properties
as follows: (1) Parameter D best correlates with storm strength Dst;
(2) the majority of geoeffective CMEs have been originated from solar
longitude 15°W, and CMEs originated away from this longitude tend
to produce weaker storms; (3) correlations between Dst and the CME
parameters improve if CMEs are separated into two groups depending
on whether their magnetic fields are oriented southward or northward
in their source regions. Based on these observations, we present two
empirical expressions for Dst in terms of L, V, and D for two groups
of CMEs, respectively. This is a new attempt to predict not only the
occurrence of geomagnetic storms, but also the storm strength (Dst)
solely based on the CME parameters.
Title: Fast Imaging Solar Spectrograph System in New Solar Telescope
Authors: Park, Y. -D.; Kim, Y. H.; Chae, J.; Goode, P. R.; Cho, K. S.;
Park, H. M.; Nah, J. K.; Jang, B. H.
Bibcode: 2010nspm.conf..189P
Altcode:
In 2004, Big Bear Solar Observatory in California, USA launched
a project for construction of the world's largest aperture solar
telescope (D = 1.6m) called New Solar Telescope(NST). University
of Hawaii (UH) and Korea Astronomy and Space Science Institute(KASI)
partly collaborate on the project. NST is a designed off-axis parabolic
Gregorian reflector with very high spatial resolution(0.07 arcsec
at 5000A) and is equipped with several scientific instruments such as
Visible Imaging Magnetograph (VIM), InfraRed Imaging Magnetograph IRIM),
and so on. Since these scientific instruments are focused on studies of
the solar photosphere, we need a post-focus instrument for the NST to
study the fine structures and dynamic patterns of the solar chromosphere
and low Transition Region (TR) layer, including filaments/prominences,
spicules, jets, micro flares, etc. For this reason, we developed and
installed a fast imaging solar spectrograph(FISS) system on the NST
withadvantages of achieving compact design with high spectral resolution
and small aberration as well as recording many solar spectral lines in
a single and/or dual band mode. FISS was installed in May, 2010 and now
we carry out a test observation. In this talk, we introduce the FISS
system and the results of the test observation after FISS installation.
Title: Seasonal, diurnal, and solar cycle variations of the
longitudinal wave structure in the low-latitude thermosphere
Authors: Kwak, Y.; Kil, H.; Lee, W.; Cho, K.
Bibcode: 2010AGUFMSA31A1707K
Altcode:
Recent studies have identified the wave-like longitudinal structure
in the low-latitude thermosphere. Direct penetration of atmospheric
tides or the ion-neutral interaction is presumably the source
of the thermospheric wave structure, but its source has not yet
been clarified. Accurate knowledge of the characteristics of the
thermospheric wave structure is essential to identify its driving
mechanism. In this study, we examine the seasonal, diurnal, and solar
cycle variations of the amplitude and phase in the thermospheric
longitudinal wave structure during the solar cycle 23 by analyzing
the total mass density data from the CHAMP satellite and the neutral
composition data from TIMED/GUVI. Our extensive study by using two
different thermospheric data source during the full solar cycle will
provide insight to an interpretation of the source of the thermospheric
wave structure.
Title: Sources of the High-Latitude Thermospheric Neutral Mass
Density Variations
Authors: Kwak, Young-Sil; Richmond, Arthur; Deng, Yue; Ahn, Byung-Ho;
Cho, Kyung-Suk
Bibcode: 2010JASS...27..329K
Altcode:
We investigate the sources of the variation of the high-latitude
thermospheric neutral mass density depending on the interplanetary
magnetic field (IMF) conditions. For this purpose, we have carried out
the National Center for Atmospheric Research Thermosphere-Ionosphere
Electrodynamics General Circulation Model (NCAR-TIEGCM) simulations
for various IMF conditions under summer condition in the southern
hemisphere. The NCAR-TIEGCM is combined with a new empirical model
that provides a forcing to the thermosphere in high latitudes. The
difference of the high-latitude thermospheric neutral mass density
(subtraction of the values for zero IMF condition from the values
for non-zero IMF conditions) shows a dependence on the IMF condition:
For negative By condition, there are significantly enhanced difference
densities in the dusk sector and around midnight. Under the positive-By
condition, there is a decrease in the early morning hours including
the dawn side poleward of -70°. For negative Bz, the difference of
the thermospheric densities shows a strong enhancement in the cusp
region and around midnight, but decreases in the dawn sector. In the
dusk sector, those values are relatively larger than those in the
dawn sector. The density difference under positive-Bz condition shows
decreases generally. The density difference is more significant under
negative-Bz condition than under positive-Bz condition. The dependence
of the density difference on the IMF conditions in high latitudes,
especially, in the dawn and dusk sectors can be explained by the
effect of thermospheric winds that are associated with the ionospheric
convection and vary following the direction of the IMF. In auroral
and cusp regions, heating of thermosphere by ionospheric currents
and/or auroral particle precipitation can be also the source of the
dependence of the density difference on the IMF conditions.
Title: Energetic electron precipitation caused by wave particle
interactions
Authors: Lee, J.; Parks, G. K.; Lee, E.; Hwang, J.; Cho, K.; Park,
Y.; Min, K. W.; Tsurutani, B.; McCarthy, M.; Kim, K.
Bibcode: 2010AGUFMSM11B1710L
Altcode:
Electron microbursts represent short electron precipitation having
durations of less than ~1 sec at L=4-8. Measurements by Korean STSAT-1
(Science and Technology SATellite) have revealed two important unique
microburst characteristics: (1) Electron microbursts are produced by
fast loss cone filling process in which the interaction time for pitch
angle scattering is less than 50 msec and (2) The e-folding energy of
perpendicular component is larger than the parallel and the loss cone
is not completely filled by electrons. To understand how wave-particle
interactions could generate microbursts, we performed a test particle
simulation and show how waves scatter electron pitch angles within the
time scale required for microburst precipitation. Application of the
rising frequency whistler mode waves to the different energy electrons
moving in a dipole magnetic field shows that the chorus magnetic wave
fields rather than electric fields are the main cause of microburst
events implying microbursts could be produced by a quasi-adiabatic
process. In addition, the simulation results show high energy electrons
can resonate with chorus at high magnetic latitudes where the loss
cone is larger, possibly explaining why precipitating microbursts have
lower e-folding energies than the trapped electrons.
Title: Tiny Pores observed by HINODE/SOT
Authors: Cho, K.; Bong, S.; Chae, J.; Kim, Y.; Park, Y.
Bibcode: 2010AGUFMSH11B1647C
Altcode:
The study of pores, small penumbraless sunspots, can give us a chance to
understand how strong magnetic fields interact with convective motions
in the photosphere. For a better understanding of this interaction, we
investigate the temporal variation of several tiny pores smaller than
2“. These pores were observed by the Solar Optical Telescope (SOT)
onboard Hinode on 2006 December 29. We have analyzed the high resolution
spectropolarimetric (SP) data and the G-band filtergrams taken during
the observation. Magnetic flux density and Doppler velocities of the
pores are estimated by applying the center of gravity (COG) method to
the SP data. The horizontal motions in and around the pores are tracked
by adopting the Nonlinear Affine Velocity Estimator (NAVE) method to
the G-band filter images. As results, we found the followings. (1)
Darkness of pores is positively correlated with magnetic flux
density. (2) Downflows always exist inside and around the pores. (3)
The speed of downflows inside the pores is negatively correlated with
their darkness. (4) The pores are surrounded by strong downflows. (5)
Brightness changes of the pores are correlated with the divergence
of mass flow (correlation coefficient > 0.9). (6) The pores in the
growing phase are associated with the converging flow pattern and the
pores in the decay phase with the diverging flow pattern. Our results
support the idea that a pore grows as magnetic flux density increases
due to the convergence of ambient mass flow and it decays with the
decrease of the flux density due to the diverging mass flow.
Title: A small-scale H-alpha eruption in the north polar limb of
the Sun observed by New Solar Telescope
Authors: Kim, Y. -H.; Park, Y. -D.; Bong, S. -Ch.; Cho, K. -S.;
Chae, J.
Bibcode: 2010nspm.conf...73K
Altcode:
The 1.6 m New Solar Telescope (NST) at Big Bear Solar Observatory
(BBSO) is the recently constructed world's largest optical solar
telescope on the ground. Up to date it has been partly operated,
i.e., observations that have been made at Nasmyth focus only without
adaptive optic (AO) system. The AO system is planned to be installed
this summer. Using the NST, we have observed the north polar limb
in H-alpha line center wavelength on 2009 August 26. A remarkable
H-alpha eruption was observed from 18:20 UT to 18:45 UT with a
relatively slower speed of about 10 km/s in its early stage. The
eruption was then slightly accelerated up to 20-30 km/s and appeared
to be deflected along the pre-existing magnetic field. The eruption
also showed several interesting characteristics such as bifurcation,
rotation, horizontal oscillation, and direction and thickness changes
of its structure during its evolution. In this talk, we report on the
observational properties of the small-scale eruption observed by the
NST and discuss their implications for magnetic reconnection.
Title: Tiny Pores Observed by Hinode/Solar Optical Telescope
Authors: Cho, Kyung-Suk; Bong, Su-Chan; Chae, Jongchul; Kim, Yeon-Han;
Park, Young-Deuk
Bibcode: 2010ApJ...723..440C
Altcode:
The study of pores, small penumbraless sunspots, can give us a chance to
understand how strong magnetic fields interact with convective motions
in the photosphere. For a better understanding of this interaction,
we investigate the temporal variation of several tiny pores smaller
than 2''. These pores were observed by the Solar Optical Telescope on
board Hinode on 2006 December 29. We have analyzed the high-resolution
spectropolarimetric (SP) data and the G-band filtergrams taken during
the observation. Magnetic flux density and Doppler velocities of the
pores are estimated by applying the center-of-gravity method to the
SP data. The horizontal motions in and around the pores are tracked
by adopting the nonlinear affine velocity estimator method to the
G-band filter images. As a result, we found the following. (1) The
darkness of the pores is positively correlated with the magnetic flux
density. (2) Downflows always exist inside and around the pores. (3)
The speed of downflows inside the pores is negatively correlated with
their darkness. (4) The pores are surrounded by strong downflows. (5)
Brightness changes of the pores are correlated with the divergence
of mass flow (correlation coefficient >0.9). (6) The pores in
the growing phase are associated with the converging flow pattern
and the pores in the decay phase with the diverging flow pattern. Our
results support the idea that a pore grows as the magnetic flux density
increases due to the convergence of ambient mass flow and it decays
with the decrease of the flux density due to the diverging mass flow.
Title: An empirical relationship between coronal mass ejection
initial speed and solar wind dynamic pressure
Authors: Cho, K. -S.; Bong, S. -C.; Moon, Y. -J.; Dryer, M.; Lee,
S. -E.; Kim, K. -H.
Bibcode: 2010JGRA..11510111C
Altcode:
Interplanetary shocks that precede coronal mass ejections (CMEs)
are mainly responsible for sudden impulses, which are characterized
by a simple step-like increase in the horizontal H component. Such
a magnetic field change has been explained as a compression of the
magnetosphere by the passage of a sudden increase in the solar wind
dynamic pressure. Strong compression of the dayside magnetopause could
cause geosynchronous satellites to be exposed to solar wind environments
where large fluctuations of the interplanetary magnetic field and highly
energetic particles are present. In this study, we chose 26 event pairs
consisting of a type II burst/CME occurring in conjunction with a sudden
commencement/sudden impulse (SC/SI) whose solar wind, and Earth magnetic
field data are available. We then investigated relationships among three
physical properties (kinetic energy, directional parameter, and speed)
of near-Sun CMEs, solar wind dynamic pressure, and SC/SI amplitude. As
a result, we found that (1) the CME speed is more highly correlated
with SC/SI amplitude than its kinetic energy and direction parameter;
(2) by adopting the empirical relationship between solar wind dynamic
pressure and amplitude of symmetric H (a steplike increase in the
horizontal H component at low latitude), we could derive an empirical
formula for the relationship between solar wind dynamic pressure near
the Earth and the CME speed; (3) the CME speed has a linear relationship
with the difference of magnetopause locations derived by using the model
of Shue et al. (1998) at the subsolar point before and after the shock
arrivals; (4) a fast CME greater than 1600 km s-1 could be a
driver of the magnetopause crossing of a spacecraft at geosynchronous
orbit. Our results show that the CME speed is an important parameter
for early prediction of geosynchronous magnetopause crossing.
Title: Characteristics of ground-level enhancement-associated solar
flares, coronal mass ejections, and solar energetic particles
Authors: Firoz, K. A.; Cho, K. -S.; Hwang, J.; Phani Kumar, D. V.;
Lee, J. J.; Oh, S. Y.; Kaushik, Subhash C.; Kudela, Karel; Rybanský,
Milan; Dorman, Lev I.
Bibcode: 2010JGRA..115.9105F
Altcode: 2010JGRA..11509105F
Ground-level enhancements (GLEs) are sudden, sharp, and
short-lived increases in cosmic ray intensities registered by
neutron monitors. These enhancements are known to take place during
powerful solar eruptions. In the present investigation, the cosmic ray
intensities registered by the Oulu neutron monitor have been studied
for the period between January 1979 and July 2009. Over this span of
time, increase rates of 32 GLEs have been deduced. In addition, we have
studied characteristics of the 32 event-associated solar flares, coronal
mass ejections (CMEs), and solar energetic particle (SEP) fluxes. We
found that all of the 32 GLEs were associated with solar flares, CMEs,
and SEP fluxes. Approximately 82% of the events were associated with
X-class flares. Most of the flares that were associated with GLEs of
increase rates >10% originated from the active regions located on
the southwest hemisphere of the Sun. The average speed (1726.17 km/s)
of GLE-associated CMEs was much faster than the average speed (423.39
km/s) of non-GLE-associated CMEs. It also became evident that ∼67%
GLEs were associated with very fast (>1500 km/s) CMEs. Although
a GLE event is often associated with a fast CME, this alone does not
necessarily cause the enhancement. Solar flares with strong optical
signatures may sometimes cause GLE. High SEP fluxes often seem to be
responsible for causing GLEs as the correlation with SEP fluxes implies.
Title: Spectral observations of FUV auroral arcs and comparison with
inverted-V precipitating electrons
Authors: Lee, C. N.; Min, K. W.; Lee, J. -J.; Parks, G. K.; Fillingim,
M. O.; Lummerzheim, D.; Cho, K. S.; Kim, K. -H.; Kim, Y. H.; Park,
Y. D.; Han, W.; Edelstein, J.; Korpela, E.
Bibcode: 2010JGRA..115.9223L
Altcode: 2010JGRA..11509223L
This paper presents first simultaneous observations of far ultraviolet
(FUV) spectra of discrete and diffuse auroras, together with
precipitating electrons measured on the same spacecraft, to emphasize
the importance of high-resolution FUV images for accurate estimation of
precipitating energy flux in the auroral region. An FUV spectrograph
image with ∼2 km × 3 km resolution show small-scale features were
embedded in the auroral arcs. Comparison of peak energies of inverted-V
events with the corresponding FUV spectra shows that the observed long
band N2 Lyman-Birge-Hopfield (LBH) emission (long LBH band
(LBHL): 160.0-171.5 nm) varied more sensitively to the peak energies
compared to the short band. Comparison of the inverted-V structures
and their energy fluxes with the LBHL irradiance for ∼10 km ×
10 km regions show they are well correlated for peak energy >2
keV. When the data are averaged over a larger area (70 km × ∼140
km), on the other hand, the LBHL irradiance becomes less bright for
the corresponding electron energy flux due to the contribution from
the low-intensity background diffuse aurora produced by secondary
electrons. This study demonstrates a reliable relationship between
precipitating electron energy flux and LBHL intensity is obtained only
if the precipitating region and FUV intensity are locally matched with a
scale of less than 10 km corresponding to the size of discrete auroras.
Title: Contributions of Heating and Forcing to the High-Latitude
Lower Thermosphere: Dependence on the Interplanetary Magnetic Field
Authors: Kwak, Young-Sil; Richmond, Arthur; Ahn, Byung-Ho; Cho,
Kyung-Suk
Bibcode: 2010JASS...27..205K
Altcode:
To better understand the physical processes that maintain the
high-latitude lower thermospheric dynamics, we have identified
relative contributions of the momentum forcing and the heating to the
high-latitude lower thermospheric winds depending on the interplanetary
magnetic field (IMF) and altitude. For this study, we performed a term
analysis of the potential vorticity equation for the high-latitude
neutral wind field in the lower thermosphere during the southern
summertime for different IMF conditions, with the aid of the National
Center for Atmospheric Research Thermosphere- Ionosphere Electrodynamics
General Circulation Model (NCAR-TIEGCM). Difference potential vorticity
forcing and heating terms, obtained by subtracting values with zero IMF
from those with non-zero IMF, are influenced by the IMF conditions. The
difference forcing is more significant for strong IMF By condition than
for strong IMF Bz condition. For negative or positive By conditions,
the difference forcings in the polar cap are larger by a factor of
about 2 than those in the auroral region. The difference heating is
the most significant for negative IMF Bz condition, and the difference
heatings in the auroral region are larger by a factor of about 1.5
than those in the polar cap region. The magnitudes of the difference
forcing and heating decrease rapidly with descending altitudes. It is
confirmed that the contribution of the forcing to the high-latitude
lower thermospheric dynamics is stronger than the contribution of the
heating to it. Especially, it is obvious that the contribution of the
forcing to the dynamics is much larger in the polar cap region than in
the auroral region and at higher altitude than at lower altitude. It
is evident that when Bz is negative condition the contribution of
the forcing is the lowest and the contribution of the heating is the
highest among the different IMF conditions.
Title: Solar proton events during the solar cycle 23 and their
association with CME parameters
Authors: Hwang, Junga; Cho, Kyung-Suk; Moon, Young-Jae; Kim, Rok-Soon;
Park, Young-Deuk
Bibcode: 2010AcAau..67..353H
Altcode:
We have studied the solar proton events associated with the coronal
mass ejections (CMEs) and flares during the solar cycle 23 (1997-2006)
in order to determine what physical parameters of the solar eruptions
might control the SPE intensity and time profile. For total 63 SPEs, we
found that (1) SPE rise time, duration time and decrease times depend
on a CME speed (cc=0.34, 0.48 and 0.48) and (2) a SPE peak intensity
depends on an earthward direction parameter of a CME as well as the
CME speed and x-ray flare intensity (cc=0.40, 0.31 and 0.37). The SPEs
were divided into two groups according to the correlation between the
CME earthward direction parameter and the SPE intensity. First group
consists of large six SPEs (>10,000 pfu at >10 MeV proton channel
of GOES satellite) and shows a very good correlation (cc=0.65) between
the SPE peak intensity and the CME earthward direction parameter. Second
group has a relatively weak SPE peak intensity and shows no correlation
(cc=0.01) between the SPE peak intensity and the CME earthward direction
parameter we found that the first group SPEs are associated with a
very fast halo CME (>1400 km/s) and most of those are located at
disk except for only one case. Especially, large six SPEs have a good
correlation with their associated CME earthward direction parameters,
implying that these events are produced by ICME-driven shocks. We
also found that those six SPEs are associated with the preceding CMEs
originated from the same solar source region and a nearby pre-existing
helmet streamer. Thus, we speculate that the preceding CME and helmet
streamer might provide seed particles for CME-driven shocks and cause
a clear separation between two groups.
Title: Space Radiation Measurement on the Polar Route onboard the
Korean Commercial Flights
Authors: Hwang, Junga; Lee, Jaejin; Cho, Kyung-Suk; Choi, Ho-Sung
Bibcode: 2010JASS...27...43H
Altcode:
This study was performed by the policy research project of Ministry
of Land, Transport and Maritime Affairs, which title is "Developing
safety standards and management of space radiation on the polar
route". In this research, total six experiments were performed using
Korean commercial flights (B747). Three of those are on the polar route
and the other three are on the north pacific route. Space radiation
exposure measured on the polar route is the average 84.7 uSv. The
simulation result using CARI-6M program gives 84.9 uSv, which is very
similar to measured value. For the departure flight using the north
pacific route, the measured space radiation is the average 74.4 uSv. It
seems that is not so different to use the polar route or not for the
return flight because the higher latitude effect causing the increase
of space radiation is compensated by the shortened flight time effect
causing decreasing space radiation exposure.
Title: Torsional Alfvén Waves As Pseudo-Magnetic Flux Ropes
Authors: Marubashi, K.; Cho, K. -S.; Park, Y. -D.
Bibcode: 2010AIPC.1216..240M
Altcode:
We examined two classes of the solar wind magnetic field variations
which show well-ordered smooth rotations with time scales of 2-7
hours. In one class, the solar wind velocity changes in good correlation
with the rotating magnetic field. It is shown that the torsional Alfvén
wave model can explain the observed variations in this class. In another
class, no significant correlation is seen between the magnetic field
and the velocity. This class is interpreted by a flux rope model and
taken as a small-scale magnetic flux rope. It is also shown that the
observed magnetic field variations in the first class could be easily
mistaken as small-scale magnetic flux ropes, if a careful analysis was
not undertaken. The present study provides a baseline to distinguish
the above two classes of rotational variations in the solar wind
magnetic field.
Title: On the relationship of cosmic ray intensity with solar,
interplanetary, and geophysical parameters
Authors: Firoz, K. A.; Kumar, D. V. Phani; Cho, K. -S.
Bibcode: 2010Ap&SS.325..185F
Altcode: 2009Ap&SS.tmp..215F
The flux rate of cosmic rays incident on the Earth’s upper atmosphere
is modulated by the solar wind and the Earth’s magnetic field. The
amount of solar wind is not constant due to changes in solar activity
in each solar cycle, and hence the level of cosmic ray modulation
varies with solar activity. In this context, we have investigated the
variability and the relationship of cosmic ray intensity with solar,
interplanetary, and geophysical parameters from January 1982 through
December 2008. Simultaneous observations have been made to quantify
the exact relationship between the cosmic ray intensity and those
parameters during the solar maxima and minima, respectively. It is
found that the stronger the interplanetary magnetic field, solar wind
plasma velocity, and solar wind plasma temperature, the weaker the
cosmic ray intensity. Hence, the lowest cosmic ray intensity has good
correlations with simultaneous solar parameters, while the highest
cosmic ray intensity does not. Our results show that higher solar
activity is responsible for a higher geomagnetic effect and vice versa.
Title: Surface Gravity and Hawking Temperature from Entropic Force
Viewpoint
Authors: Aaltonen, T.; Adelman, J.; Álvarez González, B.; Amerio,
S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari,
G.; Appel, J.; Apresyan, A.; Arisawa, T.; Artikov, A.; Asaadi, J.;
Ashmanskas, W.; Attal, A.; Aurisano, A.; Azfar, F.; Badgett, W.;
Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.;
Bartos, P.; Bauer, G.; Beauchemin, P. -H.; Bedeschi, F.; Beecher, D.;
Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas,
A.; Bhatti, A.; Binkley, M.; Bisello, D.; Bizjak, I.; Blair, R. E.;
Blocker, C.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Boisvert, V.;
Bortoletto, D.; Boudreau, J.; Boveia, A.; Brau, B.; Bridgeman, A.;
Brigliadori, L.; Bromberg, C.; Brubaker, E.; Budagov, J.; Budd,
H. S.; Budd, S.; Burkett, K.; Busetto, G.; Bussey, P.; Buzatu, A.;
Byrum, K. L.; Cabrera, S.; Calancha, C.; Camarda, S.; Campanelli,
M.; Campbell, M.; Canelli, F.; Canepa, A.; Carls, B.; Carlsmith, D.;
Carosi, R.; Carrillo, S.; Carron, S.; Casal, B.; Casarsa, M.; Castro,
A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri,
A.; Cerrito, L.; Chang, S. H.; Chen, Y. C.; Chertok, M.; Chiarelli,
G.; Chlachidze, G.; Chlebana, F.; Cho, K.; Chokheli, D.; Chou, J. P.;
Chung, K.; Chung, W. H.; Chung, Y. S.; Chwalek, T.; Ciobanu, C. I.;
Ciocci, M. A.; Clark, A.; Clark, D.; Compostella, G.; Convery, M. E.;
Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Crescioli,
F.; Cuenca Almenar, C.; Cuevas, J.; Culbertson, R.; Cully, J. C.;
Dagenhart, D.; D'Ascenzo, N.; Datta, M.; Davies, T.; de Barbaro, P.;
de Cecco, S.; Deisher, A.; de Lorenzo, G.; Dell'Orso, M.; Deluca,
C.; Demortier, L.; Deng, J.; Deninno, M.; D'Errico, M.; di Canto, A.;
di Ruzza, B.; Dittmann, J. R.; D'Onofrio, M.; Donati, S.; Dong, P.;
Dorigo, T.; Dube, S.; Ebina, K.; Elagin, A.; Erbacher, R.; Errede,
D.; Errede, S.; Ershaidat, N.; Eusebi, R.; Fang, H. C.; Farrington,
S.; Fedorko, W. T.; Feild, R. G.; Feindt, M.; Fernandez, J. P.;
Ferrazza, C.; Field, R.; Flanagan, G.; Forrest, R.; Frank, M. J.;
Franklin, M.; Freeman, J. C.; Furic, I.; Gallinaro, M.; Galyardt,
J.; Garberson, F.; Garcia, J. E.; Garfinkel, A. F.; Garosi, P.;
Gerberich, H.; Gerdes, D.; Gessler, A.; Giagu, S.; Giakoumopoulou, V.;
Giannetti, P.; Gibson, K.; Gimmell, J. L.; Ginsburg, C. M.; Giokaris,
N.; Giordani, M.; Giromini, P.; Giunta, M.; Giurgiu, G.; Glagolev, V.;
Glenzinski, D.; Gold, M.; Goldschmidt, N.; Golossanov, A.; Gomez, G.;
Gomez-Ceballos, G.; Goncharov, M.; González, O.; Gorelov, I.; Goshaw,
A. T.; Goulianos, K.; Gresele, A.; Grinstein, S.; Grosso-Pilcher, C.;
Group, R. C.; Grundler, U.; Guimaraes da Costa, J.; Gunay-Unalan, Z.;
Haber, C.; Hahn, S. R.; Halkiadakis, E.; Han, B. -Y.; Han, J. Y.;
Happacher, F.; Hara, K.; Hare, D.; Hare, M.; Harr, R. F.; Hartz,
M.; Hatakeyama, K.; Hays, C.; Heck, M.; Heinrich, J.; Herndon, M.;
Heuser, J.; Hewamanage, S.; Hidas, D.; Hill, C. S.; Hirschbuehl, D.;
Hocker, A.; Hou, S.; Houlden, M.; Hsu, S. -C.; Hughes, R. E.; Hurwitz,
M.; Husemann, U.; Hussein, M.; Huston, J.; Incandela, J.; Introzzi,
G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon,
E. J.; Jha, M. K.; Jindariani, S.; Johnson, W.; Jones, M.; Joo, K. K.;
Jun, S. Y.; Jung, J. E.; Junk, T. R.; Kamon, T.; Kar, D.; Karchin,
P. E.; Kato, Y.; Kephart, R.; Ketchum, W.; Keung, J.; Kietzman, B.;
Khotilovich, V.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, H. W.;
Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.; Kim, Y. K.; Kimura,
N.; Kirsch, L.; Klimenko, S.; Kondo, K.; Kong, D. J.; Konigsberg, J.;
Korytov, A.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Krop, D.; Krumnack,
N.; Kruse, M.; Krutelyov, V.; Kuhr, T.; Kulkarni, N. P.; Kurata, M.;
Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lancaster, M.;
Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.; Lazzizzera, I.;
Lecompte, T.; Lee, E.; Lee, H. S.; Lee, J. S.; Lee, S. W.; Leone,
S.; Lewis, J. D.; Lin, C. -J.; Linacre, J.; Lindgren, M.; Lipeles,
E.; Lister, A.; Litvintsev, D. O.; Liu, C.; Liu, T.; Lockyer, N. S.;
Loginov, A.; Lovas, L.; Lucchesi, D.; Lueck, J.; Lujan, P.; Lukens,
P.; Lungu, G.; Lys, J.; Lysak, R.; MacQueen, D.; Madrak, R.; Maeshima,
K.; Makhoul, K.; Maksimovic, P.; Malde, S.; Malik, S.; Manca, G.;
Manousakis-Katsikakis, A.; Margaroli, F.; Marino, C.; Marino, C. P.;
Martin, A.; Martin, V.; Martínez, M.; Martínez-Ballarín, R.;
Mastrandrea, P.; Mathis, M.; Mattson, M. E.; Mazzanti, P.; McFarland,
K. S.; McIntyre, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Menzione,
A.; Mesropian, C.; Miao, T.; Mietlicki, D.; Miladinovic, N.; Miller,
R.; Mills, C.; Milnik, M.; Mitra, A.; Mitselmakher, G.; Miyake,
H.; Moed, S.; Moggi, N.; Mondragon, M. N.; Moon, C. S.; Moore, R.;
Morello, M. J.; Morlock, J.; Movilla Fernandez, P.; Mülmenstädt,
J.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.;
Nagai, Y.; Naganoma, J.; Nakamura, K.; Nakano, I.; Napier, A.; Nett,
J.; Neu, C.; Neubauer, M. S.; Neubauer, S.; Nielsen, J.; Nodulman, L.;
Norman, M.; Norniella, O.; Nurse, E.; Oakes, L.; Oh, S. H.; Oh, Y. D.;
Oksuzian, I.; Okusawa, T.; Orava, R.; Osterberg, K.; Pagan Griso, S.;
Pagliarone, C.; Palencia, E.; Papadimitriou, V.; Papaikonomou, A.;
Paramanov, A. A.; Parks, B.; Pashapour, S.; Patrick, J.; Pauletta,
G.; Paulini, M.; Paus, C.; Peiffer, T.; Pellett, D. E.; Penzo, A.;
Phillips, T. J.; Piacentino, G.; Pianori, E.; Pinera, L.; Pitts, K.;
Plager, C.; Pondrom, L.; Potamianos, K.; Poukhov, O.; Prokoshin,
F.; Pronko, A.; Ptohos, F.; Pueschel, E.; Punzi, G.; Pursley, J.;
Rademacker, J.; Rahaman, A.; Ramakrishnan, V.; Ranjan, N.; Redondo,
I.; Renton, P.; Renz, M.; Rescigno, M.; Richter, S.; Rimondi, F.;
Ristori, L.; Robson, A.; Rodrigo, T.; Rodriguez, T.; Rogers, E.;
Rolli, S.; Roser, R.; Rossi, M.; Rossin, R.; Roy, P.; Ruiz, A.; Russ,
J.; Rusu, V.; Rutherford, B.; Saarikko, H.; Safonov, A.; Sakumoto,
W. K.; Santi, L.; Sartori, L.; Sato, K.; Saveliev, V.; Savoy-Navarro,
A.; Schlabach, P.; Schmidt, A.; Schmidt, E. E.; Schmidt, M. A.;
Schmidt, M. P.; Schmitt, M.; Schwarz, T.; Scodellaro, L.; Scribano,
A.; Scuri, F.; Sedov, A.; Seidel, S.; Seiya, Y.; Semenov, A.;
Sexton-Kennedy, L.; Sforza, F.; Sfyrla, A.; Shalhout, S. Z.; Shears,
T.; Shepard, P. F.; Shimojima, M.; Shiraishi, S.; Shochet, M.; Shon,
Y.; Shreyber, I.; Simonenko, A.; Sinervo, P.; Sisakyan, A.; Slaughter,
A. J.; Slaunwhite, J.; Sliwa, K.; Smith, J. R.; Snider, F. D.; Snihur,
R.; Soha, A.; Somalwar, S.; Sorin, V.; Squillacioti, P.; Stanitzki,
M.; St. Denis, R.; Stelzer, B.; Stelzer-Chilton, O.; Stentz, D.;
Strologas, J.; Strycker, G. L.; Suh, J. S.; Sukhanov, A.; Suslov,
I.; Taffard, A.; Takashima, R.; Takeuchi, Y.; Tanaka, R.; Tang, J.;
Tecchio, M.; Teng, P. K.; Thom, J.; Thome, J.; Thompson, G. A.;
Thomson, E.; Tipton, P.; Ttito-Guzmán, P.; Tkaczyk, S.; Toback,
D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.;
Torretta, D.; Totaro, P.; Trovato, M.; Tsai, S. -Y.; Tu, Y.; Turini,
N.; Ukegawa, F.; Uozumi, S.; van Remortel, N.; Varganov, A.; Vataga,
E.; Vázquez, F.; Velev, G.; Vellidis, C.; Vidal, M.; Vila, I.; Vilar,
R.; Vogel, M.; Volobouev, I.; Volpi, G.; Wagner, P.; Wagner, R. G.;
Wagner, R. L.; Wagner, W.; Wagner-Kuhr, J.; Wakisaka, T.; Wallny, R.;
Wang, S. M.; Warburton, A.; Waters, D.; Weinberger, M.; Weinelt, J.;
Wester, W. C., III; Whitehouse, B.; Whiteson, D.; Wicklund, A. B.;
Wicklund, E.; Wilbur, S.; Williams, G.; Williams, H. H.; Wilson, P.;
Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, C.; Wolfe, H.; Wright,
T.; Wu, X.; Würthwein, F.; Yagil, A.; Yamamoto, K.; Yamaoka, J.; Yang,
U. K.; Yang, Y. C.; Yao, W. M.; Yeh, G. P.; Yi, K.; Yoh, J.; Yorita,
K.; Yoshida, T.; Yu, G. B.; Yu, I.; Yu, S. S.; Yun, J. C.; Zanetti,
A.; Zeng, Y.; Zhang, X.; Zheng, Y.; Zucchelli, S.; CDF Collaboration
Bibcode: 2010MPLA...25.2825E
Altcode: 2010arXiv1003.2049C
We consider a freely falling holographic screen for the Schwarzschild
and Reissner-Nordström black holes and evaluate the entropic force à
la Verlinde. When the screen crosses the event horizon, the temperature
of the screen agrees to the Hawking temperature and the entropic force
gives rise to the surface gravity for both of the black holes.
Title: Quasi-Periodic Oscillations in Lasco Coronal Mass Ejection
Speeds
Authors: Shanmugaraju, A.; Moon, Y. -J.; Cho, K. -S.; Bong, S. C.;
Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Umapathy, S.; Vrsnak, B.
Bibcode: 2010ApJ...708..450S
Altcode:
Quasi-periodic oscillations in the speed profile of coronal mass
ejections (CMEs) in the radial distance range 2-30 solar radii are
studied. We considered the height-time data of the 307 CMEs recorded
by the Large Angle and Spectrometric Coronagraph (LASCO) during 2005
January-March. In order to study the speed-distance profile of the CMEs,
we have used only 116 events for which there are at least 10 height-time
measurements made in the LASCO field of view. The instantaneous CME
speed is estimated using a pair of height-time data points, providing
the speed-distance profile. We found quasi-periodic patterns in at
least 15 speed-distance profiles, where the speed amplitudes are larger
than the speed errors. For these events we have determined the speed
amplitude and period of oscillations. The periods of quasi-periodic
oscillations are found in the range 48-240 minutes, tending to
increase with height. The oscillations have similar properties as
those reported by Krall et al., who interpreted them in terms of the
flux-rope model. The nature of forces responsible for the motion of
CMEs and their oscillations are discussed.
Title: Special conditions for extremely large solar proton events
during solar cycle 23
Authors: Hwang, Junga; Cho, Kyung-Suk; Bong, Su-Chan; Kim, Sujin;
Krucker, Samuel; Park, Young-Deuk
Bibcode: 2010cosp...38.3041H
Altcode: 2010cosp.meet.3041H
We have investigated a relationship among the solar proton events
(SPEs), coronal mass ejec-tions (CMEs) and solar flares during the
solar cycle 23 (1997-2006). Using 63 SPE dataset, we found that SPE rise
time, duration time, and decrease times depend on CME speed (cc=0.34,
0.48 and 0.48) and SPE peak intensity depends on the CME earthward
direction parameter as well as CME speed and x-ray flare intensity
(cc=0.40, 0.31 and 0.37). While inspecting the relation between SPE
peak intensity and the CME earthward direction parameter, we found
that there are two groups: first group consists of large 6 SPEs (¿
10,000 pfu at ¿10 MeV proton channel of GOES satellite) and shows
a very good correlation (cc=0.65) between SPE peak in-tensity and
CME earthward direction parameter. The second group has a relatively
weak SPE peak intensity and shows poor correlation between SPE peak
intensity and the CME earthward direction parameter (cc=0.01). By
investigating characteristics of 6 SPEs in the first group, we found
that there are special common conditions of the extremely large proton
events (group 1); (1) all the SPEs are associated with very fast halo
CME (¿1400km/s), (2) they are almost located at disk region , (3)
they also accompany large flare (¿M7), (4) all they are preceded by
another wide CMEs, and (5) they all show helmet streamer nearby the
main CME. In this pre-sentation, we will give details of the energy
spectra of the 6 SPE events from the ERNE/HED aboard the Solar and
Heliospheric Observatory (SOHO), and onset time comparison among the
SPE, flare, type II burst, and CME.
Title: Analysis on Space Environment from the Anomalies of
Geosynchronous Satellites
Authors: Lee, Jaejin; Hwang, Junga; Bong, Su-Chan; Choi, Ho-Sung;
Cho, Il-Hynn; Cho, Kyung-Suk; Park, Young-Deuk
Bibcode: 2009JASS...26..521L
Altcode:
While it is well known that space environment can produce spacecraft
anomaly, defining space environment effects for each anomalies is
difficult. This is caused by the fact that spacecraft anomaly shows
various symptoms and reproducing it is impossible. In this study,
we try to find the conditions of when spacecraft failures happen more
frequently and give satellite operators useful information. Especially,
our study focuses on the geosynchronous satellites which cost is high
and required high reliability. We used satellite anomaly data given
by Satellite News Digest which is internet newspaper providing space
industry news. In our analysis, 88 anomaly cases occurred from 1997 to
2008 shows bad corelation with Kp index. Satellite malfunctions were
likely to happen in spring and fall and in local time from midnight to
dawn. In addition, we found the probability of anomaly increase when
high energy electron flux is high. This is more clearly appeared in
solar minimum than maximum period
Title: Geosynchronous Relativistic Electron Events Associated with
High-Speed Solar Wind Streams in 2006
Authors: Lee, Sungeun; Hwang, Junga; Lee, Jae-Jin; Cho, Kyung-Suk;
Kim, Khan-Hyuk; Yi, Yu
Bibcode: 2009JASS...26..439L
Altcode:
Recurrent enhancements of relativistic electron events at geosynchronous
orbit (GREEs) were observed in 2006. These GREE enhancements were
associated with high-speed solar wind streams coming from the same
coronal hole. For the first six months of 2006, the occurrence of
GREEs has 27 day periodicity and the GREEs were enhanced with various
flux levels. Several factors have been studied to be related to GREEs:
(1) High speed stream, (2) Pc5 ULF wave activity, (3) Southward IMF
Bz, (4) substorm occurrence, (5) Whistler mode chorus wave, and (6)
Dynamic pressure. In this paper, we have examined the effectiveness
about those parameters in selected periods.
Title: LONGITUDINAL VARIATION OF THE ANNUAL AND HEMISPHERIC
ASYMMETRIES OF THE LOW-MIDDLE LATITUDE IONOSPHERE
Authors: Kwak, Y.; Kil, H.; Oh, S.; Lee, W.; Forbes, J. M.; Cho, K.
Bibcode: 2009AGUFMSA41B..03K
Altcode:
The longitudinal variation of the annual and hemispheric asymmetries
in the low-middle latitude ionosphere at the altitude of 400 km during
solar cycle 23 is examined by analyzing the F-region plasma density
observations from the CHAMP satellite. The longitudinal variability of
the ionospheric asymmetries has not yet been investigated on the global
scale by using satellite data. In addition to the characterization of
the ionospheric asymmetries, our study extends to the investigation
of the causes of the annual and hemispheric asymmetries. The two
major sources of the asymmetries are the seasonal and hemispheric
variations of the neutral composition and meridional winds. The effect
of the neutral composition on the asymmetries will be investigated by
analyzing the neutral mass density data from CHAMP and the O/N2 ratio
data from TIMED/GUVI. The effect of meridional winds on the asymmetries
will be investigated by analyzing the ROCSAT-1 meridional ion velocity
data as a proxy of the meridional neutral wind.
Title: Relationship of Ground Level Enhancement with Solar Flare,
Coronal Mass Ejection and Solar Energetic Particle
Authors: Firoz, K. M.; Cho, K.; Lee, J.; Kumar, P.; Hwang, J.; Oh,
S. Y.
Bibcode: 2009AGUFMSH33A1485F
Altcode:
Ground level enhancement (GLE) is the sudden increase in the cosmic ray
intensity (CRI) which is thought to be caused by solar eruption. In
this study we have analyzed the CRI data from 1968 through 2008
registered by several Neutron Monitors and deduced increase rate (%)
of GLE events using the 5-minute data mainly from Oulu Neutron Monitor
(ONM) and Calgary Neutron Monitor (CNM). To investigate the relations of
GLEs with solar X-ray flares, coronal mass ejections (CMEs) and solar
energetic particles (SEPs), we have inspected the peak time and peak
intensity differences of GLE events. As results, we have found that
the peak time (UT) differences vary mostly within ±20 minutes when the
peak intensities vary mostly within ±50% at CNM and ONM. It has been
observed that GLE events are associated with strong flares as well as
fast /halo CMEs. Almost 62% of the flares associated with strong GLE
were originated from south-west active region while 38% of the flares
were originated from north-west active region. On an exception, an
apparently weaker flare associated with GLE is not actually a weaker
flare, rather a large flare existing behind the limb. The average of
GLE associated CMEs is (1916.60 km/s) much faster than the average
(458.53 km/s) of all CMEs. The fluences of the high energy proton
flux (PF > 100MeV) associated with the GLE are stronger than those
associated with non-GLE events. We will introduce our results briefly
and discuss on the relationship of GLE with flare, CME and SEP.
Title: Relationship Between Solar Proton Events and Corona Mass
Ejection Over the Solar Cycle 23
Authors: Hwang, Junga; Lee, Jaejin; Cho, Kyung-Suk; Kim, Rok-Sun;
Moon, Yong-Jae; Park, Young-Deuk
Bibcode: 2009JASS...26..479H
Altcode:
We studied the solar proton events (SPEs) associated with coronal mass
ejections (CMEs) during the solar cycle 23 (1997-2006). Using 63 SPE
dataset, we investigated the relationship among SPE, flare, and CME,
and found that (1) SPE rise time and duration time depend on CME speed
and the earthward direction parameter of the CME, and (2) the SPE
peak intensity depends on CME speed and X-ray Flare intensity. While
inspecting the relation between SPE peak intensity and the direction
parameter, we found there are two groups: first group consists of
large six SPEs (> 10,000 pfu at > 10 MeV proton channel of GOES
satellite) and shows strong correlation (cc = 0.65) between SPE peak
intensity and CME direction parameter. The second group has a weak
intensity and shows poor correlation between SPE peak intensity and
the direction parameter (cc = 0.01). By investigating characteristics
of the first group, we found that all the SPEs are associated with
very fast halo CME (> 1400km/s) and also they are mostly located at
central region and within ∼20± latitude and ∼30± longitude strip.
Title: Large solar proton events associated with coronal mass
ejections
Authors: Hwang, J.; Cho, K.; Kim, R.; Moon, Y.; Park, Y.
Bibcode: 2009AGUFMSH33A1483H
Altcode:
We studied the solar proton events (SPEs) associated with coronal mass
ejections (CMEs) during the solar cycle 23 (1997-2006). Using 63 SPE
dataset, we investigated the relationship among SPE, flare, and CME,
and found that (1) SPE rise time and duration time depend on CME speed
and the earthward direction parameter of the CME, and (2) the SPE
peak intensity depends on CME speed and X-ray Flare intensity. While
inspecting the relation between SPE peak intensity and the direction
parameter, we found there are two groups: first group consists of
large six SPEs (> 10,000 pfu at >10 MeV proton channel of GOES
satellite) and shows strong correlation (cc=0.93) between SPE peak
intensity and CME direction parameter. The second group has a relatively
weak SPE peak intensity and shows poor correlation between SPE peak
intensity and the direction parameter. By investigating characteristics
of the first group, we found that all the SPEs are associated with very
fast halo CME (>1400km/s), there are preceding CMEs originated from
the same solar source region and CME-streamer interaction. We speculate
that the preceding CME and helmet streamer might provide seed particles
for CME-driven shocks that follow. It is also found for the first group
that there is a negative correlation between SPE peak intensity and
SPE rise time, and that between the peak intensity and SPE duration
time. In case of the second group, we found a positive correlation
between those. In this talk, we will briefly present our results on
the relationship between SPEs and the properties of the associated CMEs.
Title: Analysis of auroras caused by precipitation of high energy
electrons
Authors: Lee, C.; Lee, J.; Min, K.; Parks, G. K.; Fillingim, M. O.;
Cho, K.; Kim, K.; Han, W.; Edelstein, J.
Bibcode: 2009AGUFMSM41A1684L
Altcode:
It has been regarded that keV electrons precipitating into the upper
atmosphere are the main source of auroral emissions. Hence, extensive
efforts have been made to relate observed auroral intensity to the
precipitating energy flux of these electrons while the role of the
electrons above ~ 20 keV was not examined well. Our previous study
showed the intensity of the long LBH (1600 Å - 1715 Å) was enhanced
very much compared to that of the short LBH (1400 Å - 1500 Å) when
the characteristic energy of the precipitating electrons increased
from 1 keV to >7 keV, in accordance with the theoretical models. In
this paper, we would like to present the results of our study for even
higher energy electrons. Measurement of electrons for the energy above
~ 20 keV is technically difficult and in fact, we were unable to find
any previous observations for this high energy range except the one
made on STSAT-1 for the electrons of 170 ~ 360 keV. Thus, we selected
the events in which the fluxes both in the low energy (100 eV ~ 20 keV)
and in the high energy (170 ~ 360 keV) were enhanced, and examined the
auroral spectra for these events observed simultaneously by the imaging
spectrograph on the same spacecraft. While the accurate characteristic
energy could not be determined because of the gap in the energy range,
our result showed the intensity ratio of the long LBH to the short
LBH ranged from 1.2 to 2.0 in these events, in contrast to 1.0 or
smaller for the events in which the highest enhancement was seen only
in the low energy. Our study suggests that intense auroras might be
accompanied by high energy electrons above 20 keV.
Title: Magnetic Reconnection During the Two-phase Evolution of a
Solar Eruptive Flare
Authors: Joshi, Bhuwan; Veronig, Astrid; Cho, K. -S.; Bong, S. -C.;
Somov, B. V.; Moon, Y. -J.; Lee, Jeongwoo; Manoharan, P. K.; Kim,
Y. -H.
Bibcode: 2009ApJ...706.1438J
Altcode: 2008arXiv0809.2484J
We present a detailed multi-wavelength analysis and interpretation of
the evolution of an M7.6 flare that occurred near the southeast limb on
2003 October 24. Pre-flare images at TRACE 195 Å show that the bright
and complex system of coronal loops already existed at the flaring
site. The X-ray observations of the flare taken from the Reuven Ramaty
High Energy Solar Spectroscopic Imager (RHESSI) spacecraft reveal two
phases of the flare evolution. The first phase is characterized by the
altitude decrease of the X-ray looptop (LT) source for ~11 minutes. Such
a long duration of the descending LT source motion is reported for
the first time. The EUV loops, located below the X-ray LT source,
also undergo contraction with similar speed (~15 km s-1)
in this interval. During the second phase the two distinct hard X-ray
footpoint (FP) sources are observed which correlate well with UV and
Hα flare ribbons. The X-ray LT source now exhibits upward motion as
anticipated from the standard flare model. The RHESSI spectra during the
first phase are soft and indicative of hot thermal emission from flaring
loops with temperatures T > 25 MK at the early stage. On the other
hand, the spectra at high energies (ɛ gsim 25 keV) follow hard power
laws during the second phase (γ = 2.6-2.8). We show that the observed
motion of the LT and FP sources can be understood as a consequence
of three-dimensional magnetic reconnection at a separator in the
corona. During the first phase of the flare, the reconnection releases
an excess of magnetic energy related to the magnetic tensions generated
before a flare by the shear flows in the photosphere. The relaxation
of the associated magnetic shear in the corona by the reconnection
process explains the descending motion of the LT source. During the
second phase, the ordinary reconnection process dominates describing
the energy release in terms of the standard model of large eruptive
flares with increasing FP separation and upward motion of the LT source.
Title: Near-Simultaneous Observations of X-Ray Plasma Ejection,
Coronal Mass Ejection, and Type II Radio Burst
Authors: Kim, Yeon-Han; Bong, Su-Chan; Park, Y. -D.; Cho, K. -S.;
Moon, Y. -J.
Bibcode: 2009ApJ...705.1721K
Altcode:
We report the first simultaneous observation of X-ray plasma ejection
(XPE), coronal mass ejection (CME), and type II solar radio burst on
1999 October 26. First, an XPE was observed from 21:12 UT to 21:24 UT in
the Yohkoh SXT field of view (1.1 to 1.4 R sun). The XPE was
accelerated with a speed range from 190 to 410 km s-1 and its
average speed is about 290 km s-1. Second, the associated CME
was observed by the Mauna Loa Mk4 coronameter (1.1-2.8 R sun)
from 21:16 UT. The CME front was clearly identified at 21:26 UT and
propagated with a deceleration of about -110 m s-2. Its
average speed is about 360 km s-1. At the type II burst
start time (21:25 UT), the height of the CME front is around 1.7 R
sun and its speed is about 470 km s-1. Third,
a type II solar radio burst was observed from 21:25 UT to 21:43 UT
by the Culgoora solar radio spectrograph. The burst shows three
emission patches during this observing period and the emission
heights of the burst are estimated to be about 1.3 R sun
(21:25 UT), 1.4 R sun (21:30 UT), and 1.8 R sun
(21:40 UT). By comparing these three phenomena, we find that: (1)
kinematically, while the XPE shows acceleration, the associated CME
front shows deceleration; (2) there is an obvious height difference
(0.3 R sun) between the CME front and the XPE front around
21:24 UT and the formation height of the type II burst is close to the
trajectory extrapolated from the XPE front; (3) both speeds of the
XPE and the CME are comparable with each other around the starting
time of the type II burst. Considering the formation height and the
speed of the type II burst, we suggest that its first emission is due
to the coronal shock generated by the XPE and the other two emissions
are driven by the CME flank interacting with the high-density streamer.
Title: A Coronal Mass Ejection and Hard X-Ray Emissions Associated
with the Kink Instability
Authors: Cho, Kyung-Suk; Lee, Jeongwoo; Bong, Su-Chan; Kim, Yeon-Han;
Joshi, Bhuwan; Park, Young-Deuk
Bibcode: 2009ApJ...703....1C
Altcode:
We present a morphological study of the 2004 August 18 solar eruption
that occurred in the active region NOAA 10656 near the west limb using
extreme-ultraviolet (EUV) data from the Transition Region and Coronal
Explorer (TRACE), Hα filtergram of Big Bear Solar Observatory, white
light images of Mauna Loa Solar Observatory (MLSO), hard X-ray (HXR)
data of the Reuven Ramaty High Energy Solar Spectroscopic Imager
(RHESSI), and microwave data of the Owens Valley Solar Array. In
this event, we have an excellent set of observations for tracing the
early evolution of the coronal mass ejection (CME) from a flux rope
emergence to its propagation into space as a well-connected series
of events thanks to the coronameter's field of view (FOV) down to
1.1 solar radius in an overlap with that of the TRACE. This data
set reveals continuously evolving EUV, Hα, and WL features that
suggest the rise of a small, low-lying loop, its writhing motion,
break of the kinked loop at its crossing point, and transformation
of the ejecta to the CME. The HXR and microwave sources are found
in varying locations with a complicated temporal dependence, which,
we interpret, is due to two successive flares in the event. The first
flare appears to be associated with the rise of the small loop, which
then triggers the second flare. During the second flare a HXR coronal
source is detected at the crossing point of the kinked loop, and more
intriguingly, the kinked loop apparently breaks at the crossing point
of the two legs, which indicates a magnetic reconnection at the X-point
configuration. After the break of the kinked UV loop, a CME structure
shows up in the MLSO FOV, and propagates away from the Sun. It is
concluded that this CME occurred due to the kink instability.
Title: A Comparison of the Initial Speed of Coronal Mass Ejections
with the Magnetic Flux and Magnetic Helicity of Magnetic Clouds
Authors: Sung, S. -K.; Marubashi, K.; Cho, K. -S.; Kim, Y. -H.; Kim,
K. -H.; Chae, J.; Moon, Y. -J.; Kim, I. -H.
Bibcode: 2009ApJ...699..298S
Altcode:
To investigate the relationship between the speed of a coronal mass
ejection (CME) and the magnetic energy released during its eruption,
we have compared the initial speed of CMEs (V CME) and the
two parameters of their associated magnetic clouds (MC), magnetic
flux (F MC), and magnetic helicity per unit length
(|H MC|/L), for 34 pairs of CMEs and MCs. The values
of these parameters in each MC have been determined by fitting
the magnetic data of the MC to the linear force-free cylindrical
model. As a result, we found that there are positive correlations
between V 2 CME and F MC, and
between V 2 CME and |H MC|/L. It
is also found that the kinetic energy of CMEs (E CME)
is correlated with F MC and |H MC|/L of the
associated MC. In contrast, we found no significant correlation between
langV MCrang2 and F MC, nor between
langV MCrang2 and |H MC|/L. Our
results support the notion that the eruption of a CME is related to
the magnetic helicity of the source active region.
Title: Comet Observations [850 Cordell-Lorenz Observatory, Sewanee]
Authors: Durig, D. T.; Kharel, P.; Boppana, S.; McCutcheon, S. R.;
White, L. C.; Bendana, M. E.; Carpenetti, R. N.; Meadows, E. S.;
Forbes, D. D.; Springer, N. G.; Lu, D.; Taylor, L. E.; Johnson-Bann,
G. E.; Norom, A. I.; Struthers, S. C.; Wong, A.; Liu, H.; Cho, K.;
Moscoso, A. M.; Neyra, S. A.; Agyemang, S. A. N.; Holt, R. A.
Bibcode: 2009MPC..66408..16D
Altcode:
No abstract at ADS
Title: Minor Planet Observations [850 Cordell-Lorenz Observatory,
Sewanee]
Authors: Durig, D. T.; Kharel, P.; White, L. C.; Boppana, S.;
McCutcheon, S. R.; Bendana, M. E.; Carpenetti, R. N.; Meadows, E. S.;
Forbes, D. D.; Springer, N. G.; Lu, D.; Taylor, L. E.; Johnson-Bann,
G. E.; Nnorom, A. I.; Struthers, S. C.; Wong, A.; Liu, H.; Cho, K.;
Moscoso, A. M.; Neyra, S. A.; Agyemang, S. A. N.; Holt, R. A.
Bibcode: 2009MPC..66456...9D
Altcode:
No abstract at ADS
Title: Effects of Source Position on the DH-Type II CME Properties
Authors: Shanmugarju, A.; Moon, Y. J.; Cho, K. S.; Umapathy, S.
Bibcode: 2009JKAS...42...55S
Altcode:
No abstract at ADS
Title: Observations of Comets
Authors: Almendros, I.; Naves, R.; Campas, M.; Reina, E.; Scotti,
J. V.; Kadota, K.; Abe, H.; Christie, G. W.; Natusch, T.; Jung, M.;
Bill, H.; Baransky, A.; Churyumov, K.; Ponomarenko, V.; Hill, R. E.;
Beshore, E.; Beshore, E. C.; Boattini, A.; Gibbs, A. R.; Grauer, A. D.;
Kowalski, R. A.; Larson, S. M.; Bezpalko, M.; Torres, D.; Kracke, R.;
Spitz, G.; Blythe, M.; Stuart, J.; Elliott, R.; Durig, D. T.; Kharel,
P.; Boppana, S.; McCutcheon, S. R.; White, L. C.; Bendana, M. E.;
Carpenetti, R. N.; Meadows, E. S.; Forbes, D. D.; Springer, N. G.;
Lu, D.; Taylor, L. E.; Johnson-Bann, G. E.; Norom, A. I.; Struthers,
S. C.; Wong, A.; Liu, H.; Cho, K.; Ikari, Y.; Castellano, J.; Vidal,
J. R.; Kocher, P.; Rinner, C.; Kugel, F.; Bacci, P.; Tonincelli, M.;
Marinello, W.; Jacquinot, H.; Camilleri, P.; Guido, E.; Prosperi,
E.; Sostero, G.; Camarasa, J.; Bosch, J. M.; Bryssinck, E.; Ohshima,
Y.; Sato, H.; Koishikawa, M.; Chestnov, D.; Elenin, L.; Mills, M.;
Sherrod, P. C.; Bell, C.; Birmingham, D. A.; Colazo, C.; Guida, R.;
Mazzone, F. D.; Robledo, W.; Montivero, C.; Fernandez, A.; Garcia,
M. A.; Curto, J.; Temprano, J.; Carreno, A.; Piqueras, J.; Rodriguez,
M.; Hernandez, J. F.; Martin, J. J.; Garcia, F.; Muler, G.; Henriquez,
J. A.; Benavides, R.; Climent, T.; Marsden, B. G.
Bibcode: 2009MPEC....M...52A
Altcode:
No abstract at ADS
Title: Nonthermal Velocity and Differential Emission Measure at
Preflare Site using Hinode EIS
Authors: Kim, Sujin; Moon, Y.; Lee, K.; Cho, K.; Kim, Y.
Bibcode: 2009SPD....40.1907K
Altcode:
We have made an imaging spectroscopic study at the preflare site, which
is associated with a C4.2 flare that occurred on 2007 January 16 using
Hinode EUV Imaging Spectrometer (EIS) data. Examining many spectral
lines of EIS, we determined intensities, Doppler velocities, and
nonthermal velocities at the preflare site, which is cospatial with the
place where the flare occurred, as well as at a nearby quiet loop. Also
we derived the differential emission measure (DEM) for each region
using the intensity at several wavelengths and the density obtained
by the filter ratio (Fe XII λ186.88/λ195.12) method. A comparison
of nonthermal velocities and DEM at both regions reveals several
interesting characteristics of the preflare site as follows. First, the
nonthermal velocities at the preflare site are noticeably higher than
that at the quiet loop for all wavelengths. Second, the difference
of the nonthermal velocities at between the preflare site and the
quite loop has a maximum value at the lowest temperature, log T =
5.8. Third, while the DEM curve for the quiet loop is broad over coronal
temperatures, that for the preflare site shows double peaks near log
T = 6.4 and log T = 5.3. These results imply that there should be
strong nonthermal motions and hot components at the lower temperature
atmosphere just before the preflare time. Regarding hot components, we
suggest two possibilities: the activity of multi-thermal loops or lower
atmospheric heating caused by small-scale magnetic reconnection process.
Title: Impacts of torus model on studies of geometrical relationships
between interplanetary magnetic clouds and their solar origins
Authors: Marubashi, Katsuhide; Sung, Suk-Kyung; Cho, Kyung-Suk;
Lepping, Ronald P.
Bibcode: 2009EP&S...61..589M
Altcode: 2009EP&S...61L.589M
Our recent analysis of interplanetary magnetic clouds (MCs) showed
that the orientations of MC axes determined by a model fitting with
curvature of MCs taken into account (referred to as a torus model,
hereafter) can be significantly different from those obtained from
fittings with a straight cylinder model. Motivated by this finding,
we re-examined geometrical relationships between magnetic field
structures of MCs and their solar origins. This paper describes the
results of the re-examination with special attention paid to two MC
events, for which different orientations of MC axes were obtained from
a torus model and a cylinder model. For both cases, it is shown that the
torus models give the MC geometries of magnetic field structures in good
agreement with those of coronal arcade structures which were formed in
association with the launch of MCs along the magnetic field inversion
lines. Summarizing the analysis results for 12 MCs investigated here,
we conclude that: (1) the formation of coronal arcade structure is
a good indication of MC formation; (2) MC geometries can be obtained
that are consistent with the coronal arcades with respect to the axis
orientation and the magnetic field structure including chirality,
indicating that no significant direction changes occurred during the
propagation of MCs through the interplanetary medium.
Title: The Korean Solar Radio Burst Locator (KSRBL)
Authors: Dou, Yujiang; Gary, Dale E.; Liu, Zhiwei; Nita, Gelu M.;
Bong, Su-Chan; Cho, Kyung-Suk; Park, Young-Deuk; Moon, Yong-Jae
Bibcode: 2009PASP..121..512D
Altcode:
This paper describes the design and operation of the Korean Solar Radio
Burst Locator (KSRBL). The KSRBL is a radio spectrometer designed to
observe solar decimeter and microwave bursts over a wide band (0.245-18
GHz) as well as to detect the burst locations without interferometry
or mechanical sweeping. As a prototype, it is temporarily observing
at the Owens Valley Radio Observatory (OVRO), California, USA, and
after commissioning will be operated at the Korea Astronomy and Space
Science Institute (KASI), Daejeon, Republic of Korea. The control
system can agilely choose four 500 MHz intermediate frequency (IF)
bands (2 GHz instantaneous bandwidth) from the entire 0.245-18 GHz
band, with a standard time resolution of 100 ms, although higher time
resolution is possible subject to data-rate constraints. To cover the
entire band requires 10 tunings, which are therefore completed in 1
s. Each 500 MHz band is sampled at a 1 GS s-1 (gigasample per
second) rate, and 4096 time samples are Fast Fourier transformed (FFT)
to 2048 subchannels for a frequency resolution of 0.24 MHz. To cover
the entire range also requires two different feeds, a dual-frequency
Yagi centered at 245 and 410 MHz, and a broadband spiral feed covering
0.5-18 GHz. The dynamic range is 35 dB over the 0.5-18 GHz band, and 55
dB in the 245 and 410 MHz bands, set by using switchable attenuators in
steps of 5 dB. Each 500 MHz IF has a further 63 dB of settable analog
attenuation. The characteristics of the spiral feed provide the ability
to locate flaring sources on the Sun to typically 2‧. The KSRBL will
provide a broadband view of solar bursts for the purposes of studying
solar activity for basic research, and for monitoring solar activity
as the source of Space Weather and solar-terrestrial effects.
Title: Geometrical Implication of the CME Earthward Direction
Parameter and its Comparison with Cone Model Parameters
Authors: Moon, Y. J.; Kim, R. S.; Cho, K. S.
Bibcode: 2009JKAS...42...27M
Altcode:
No abstract at ADS
Title: A World-Wide Net of Solar Radio Spectrometers: e-CALLISTO
Authors: Benz, A. O.; Monstein, C.; Meyer, H.; Manoharan, P. K.;
Ramesh, R.; Altyntsev, A.; Lara, A.; Paez, J.; Cho, K. -S.
Bibcode: 2009EM&P..104..277B
Altcode: 2009EM&P..tmp....2B
Radio spectrometers of the CALLISTO type to observe solar flares have
been distributed to nine locations around the globe. The instruments
observe automatically, their data is collected every day via internet
and stored in a central data base. A public web-interface exists
through which data can be browsed and retrieved. The nine instruments
form a network called e-CALLISTO. It is still growing in the number
of stations, as redundancy is desirable for full 24 h coverage of
the solar radio emission in the meter and low decimeter band. The
e-CALLISTO system has already proven to be a valuable new tool for
monitoring solar activity and for space weather research.
Title: On the Relation Between the Sun and Climate Change with the
Solar North-South Asymmetry
Authors: Cho, I. -H.; Kwak, Y. -S.; Cho, K. -S.; Choi, H. -S.; Chang,
H. -Y.
Bibcode: 2009JASS...26...25C
Altcode:
We report the relation between the solar activity and terrestrial
climate change with the solar north-south asymmetry. For this purpose,
we calculate sliding correlation coefficients between sunspot numbers
and earth's mean annual temperature anomalies. Then, we compare
the epoch that the sign of correlation changes with the epoch that
the sign of the solar north-south asymmetry changes. We obtain that
corresponding times are 1907 and 1985, respectively. Further more,
these two epoches are well consistent with those of signs of the
solar north-south asymmetry changes. We also obtain that the plot
between sunspot numbers and temperature anomalies could be classified
by 1907 and 1985. We conclude that temperature anomalies are shown to
be negatively correlated with sunspot numbers when the southern solar
hemisphere is more active, and vice versa.
Title: Construction of AN E-Callisto Station in Korea
Authors: Bong, Su-Chan; Kim, Yeon-Han; Roh, Hee-Seon; Cho, Kyung-Suk;
Park, Young-Deuk; Choi, Seong-Hwan; Baek, Ji-Hye; Monstein, Christian;
Benz, Arnold O.; Moon, Yong-Jae; Kim, Sung-Soo S.
Bibcode: 2009JKAS...42....1B
Altcode:
No abstract at ADS
Title: Statistical Analysis of the Relationships among Coronal Holes,
Corotating Interaction Regions, and Geomagnetic Storms
Authors: Choi, Yunhee; Moon, Y. -J.; Choi, Seonghwan; Baek, Ji-Hye;
Kim, Sungsoo S.; Cho, K. -S.; Choe, G. S.
Bibcode: 2009SoPh..254..311C
Altcode:
We have examined the relationships among coronal holes (CHs), corotating
interaction regions (CIRs), and geomagnetic storms in the period 1996 -
2003. We have identified 123 CIRs with forward and reverse shock or
wave features in ACE and Wind data and have linked them to coronal
holes shown in National Solar Observatory/Kitt Peak (NSO/KP) daily He
I 10 830 Å maps considering the Sun - Earth transit time of the solar
wind with the observed wind speed. A sample of 107 CH - CIR pairs is
thus identified. We have examined the magnetic polarity, location, and
area of the CHs as well as their association with geomagnetic storms
(Dst≤−50 nT). For all pairs, the magnetic polarity of the CHs is
found to be consistent with the sunward (or earthward) direction of
the interplanetary magnetic fields (IMFs), which confirms the linkage
between the CHs and the CIRs in the sample. Our statistical analysis
shows that (1) the mean longitude of the center of CHs is about 8°E,
(2) 74% of the CHs are located between 30°S and 30°N (i.e., mostly
in the equatorial regions), (3) 46% of the CIRs are associated with
geomagnetic storms, (4) the area of geoeffective coronal holes is
found to be larger than 0.12% of the solar hemisphere area, and (5)
the maximum convective electric field Ey in the solar
wind is much more highly correlated with the Dst index than any other
solar or interplanetary parameter. In addition, we found that there is
also a semiannual variation of CIR-associated geomagnetic storms and
discovered new tendencies as follows: For negative-polarity coronal
holes, the percentage (59%; 16 out of 27 events) of CIRs associated
with geomagnetic storms in the first half of the year is much larger
than that (25%; 6 out of 24 events) in the second half of the year and
the occurrence percentage (63%; 15 out of 24 events) of CIR-associated
storms in the southern hemisphere is significantly larger than that
(26%; 7 out of 27 events) in the northern hemisphere. Positive-polarity
coronal holes exhibit an opposite tendency.
Title: Solar Magnetic Polarity Dependence of the Seasonal Occurrence
of Geomagnetic Storms
Authors: Oh, S.; Yi, Y.; Cho, K.
Bibcode: 2008AGUFMSH21B1604O
Altcode:
To investigate the seasonal variation and its solar magnetic polarity
dependence of geomagnetic activity, we performed the statistical
analysis on the geomagnetic storms defined by Dst index. We used storm
data for 5 years each at solar minimums during the 4 solar cycles 19
to 22 (1962-1998) for even two of each solar magnetic polarities. We
selected total 156 geomagnetic storms of Dst(min) < -50 nT, |Dst|
> 100 nT and compared the monthly occurrence of those storms. The
geomagnetic storms occurred more frequently in spring and fall
seasons for all solar cycle minimums regardless of the solar magnetic
polarity. It is in the summer and winter seasons that the geomagnetic
storm occurrence rate increased more for the solar cycles 20 and 22
when the solar magnetic polarity is anti-parallel to the Earth's than
the solar cycles 19 and 21.
Title: Low coronal observations of metric type II associated CMEs
by MLSO coronameters
Authors: Cho, K. -S.; Bong, S. -C.; Kim, Y. -H.; Moon, Y. -J.; Dryer,
M.; Shanmugaraju, A.; Lee, J.; Park, Y. D.
Bibcode: 2008A&A...491..873C
Altcode:
Aims: We have investigated the relationship between coronal mass
ejections (CMEs) and coronal type II radio bursts by using type II
associated CMEs whose low coronal observations by MLSO MK coronameters
(1.08-2.85 solar radii for MK4) were available.
Methods: For
this we considered all type II burst data at 17:00 UT to 22:00 UT
from 1996 to 2003, and then compared them with CME images that were
obtained during the same MLSO (Mauna Loa Solar Observatory) observing
periods. As a result, we selected 19 type II associated CMEs whose
kinematics are well identified. A relationship between CMEs and type
IIs has been examined in terms of spatial and temporal closeness without
any extrapolation of CME kinematics as well as in terms of CME-streamer
interaction.
Results: We found that: (1) except one event, all the
metric type II events occur simultaneously or after the CME appearance
in MK field of view within 30 min, mostly within 10 min after; (2)
the distribution of height difference between the CME front and type
II formation shows that there are double peaks, one at the CME fronts
and the other at about 1 solar radius behind the front; (3) about half
of the events (9/19) are identified to have CME-streamer interaction
(seven streamer deflection and two overlapping), and the interaction
heights are very similar to those of type II formation as well as their
interaction times are nearly coincident with those of type II starting;
(4) for the other events (10/19), the CME front heights at the starting
time of type IIs are comparable to the heights of type II formation.
Conclusions: Our low coronal observations of type II associated CMEs
suggest that CME front and/or CME-streamer interaction at CME flank
are two main mechanisms to generate type II bursts.
Title: Estimation of Spicule Magnetic Field Using Observed MHD Waves
by the Hinode SOT
Authors: Kim, Yeon-Han; Bong, Su-Chan; Park, Young-Deuk; Cho,
Kyung-Suk; Moon, Yong-Jae; Suematsu, Yoshinori
Bibcode: 2008JKAS...41..173K
Altcode:
No abstract at ADS
Title: Comparison of Interplanetary Magnetic Clouds Observed by ACE
and STEREO
Authors: Marubashi, K.; Sung, S.; Bong, S.; Cho, K.
Bibcode: 2008AGUFMSH13B1557M
Altcode:
The solar wind observations by STEREO A and B, together with the
ACE spacecraft provide an unprecedented opportunity to examine
three-dimensional structures of interplanetary magnetic clouds
(MCs). The purpose of this study is to get a better insight into their
spatial extent, differences in their detailed structures depending on
the geometry of spacecraft encounter, and possible deformation due
to interactions with other solar wind structures. For this purpose,
we surveyed the STEREO and ACE data for the period from January 2007
through February 2008. As a result, we found that each of the three
spacecraft encountered four or five well-defined MC during this period,
in which the separation of STEREO A (B) from the Earth changed from 0
to 22 (-24) degrees. The observations from 21 to 23 May, 2007 provide a
data set that is the most appropriate to our purpose. ACE detected two
MCs (No. 1, May 21/2300 - May 22/1300; No.2, May 23/0300 - May 23/1200),
and a less evident MC-like structure in between. Interestingly, the MC
No. 1 was observed by STEREO B in a more beautiful form, with only a
"remnant-like" structure observed by STEREO A, whereas the MC No.2 was
observed by STEREO A in a more beautiful form than observed by ACE. It
is supposed that these two MCs observed by ACE provide some evidence
for deformation due to MC- MC interactions, although the analysis is not
completed yet. On another topic, we need to admit that the probability
for the same MCs to be observed by two spacecrafts is low despite the
small separation between them. This observational fact can be explained
by the direction of MC axis obtained from model fittings. This implies
that we can obtain observational information about the spatial extent of
MC only for those MCs with axes nearly parallel to the ecliptic plane.
Title: Reply to comment by N. Gopalswamy and H. Xie on ``Prediction
of the 1-AU arrival times of CME-associated interplanetary shocks:
Evaluation of an empirical interplanetary shock propagation model''
Authors: Kim, K. -H.; Moon, Y. -J.; Cho, K. -S.
Bibcode: 2008JGRA..11310106K
Altcode:
No abstract at ADS
Title: Comparison of SOHO UVCS and MLSO MK4 coronameter densities
Authors: Lee, K. -S.; Moon, Y. -J.; Kim, K. -S.; Lee, J. -Y.; Cho,
K. -S.; Choe, G. S.
Bibcode: 2008A&A...486.1009L
Altcode:
We have compared the density distributions of solar corona obtained
by SOHO Ultraviolet Coronagraph Spectrometer (UVCS) and Mauna Loa
Solar Observatory (MLSO) MK4 coronameter. This is the first attempt
to compare the coronal densities estimated by the two instruments. In
the spectral data of UVCS, we have selected two emission lines (O
VI 1032 Åand 1037.6 Å), which have both radiative and collisional
components. The coronal number density is determined from the ratio
of these two components. The MK4 coronameter has a field of view
ranging from 1.08 to 2.85 solar radii. The coronal density can be
determined by inverting MLSO MK4 polarization maps. We find that the
mean electron number density in a helmet streamer observed by MK4 on
2003 April 28 is fairly consistent with that observed by UVCS. For a
coronal hole and an active region observed on 1999 October 19 and 24,
the MK4 coronal densities are close to those from the UVCS within a
factor of two; the former values are twice the latter at 1.7 solar radii
and closer to the latter at higher altitudes. Our results demonstrate
that MK4 polarization data can provide us with a coronal density
distribution in a large field of view with a time cadence of about
three minutes. We suggest that the MK4 data can be used to derive 2-D
density distributions of coronal structures and further to estimate
the heights of CME-associated type II shocks.
Title: Comparison between the KOMPSAT-1 drag derived density and the
MSISE model density during strong solar and/or geomagnetic activities
Authors: Park, J.; Moon, Y. -J.; Kim, K. -H.; Cho, K. -S.; Kim,
H. -D.; Kwak, Y. -S.; Kim, Y. -H.; Park, Y. -D.; Yi, Y.
Bibcode: 2008EP&S...60..601P
Altcode:
We have compared the KOrea Multi-Purpose SATellite-1 (KOMPSAT-1)
drag derived density with the MSISE model (NRLMSISE-00 and MSISE-90)
density during strong solar and/or geomagnetic activities. It is
well known that there are two major mechanisms to induce satellite
drag caused by atmospheric density enhancement: the heating by solar
EUV radiation and joule heating associated with local geomagnetic
current enhancements during geomagnetic storms. For this work we
select five events dominated by the radiation effect and/or the
geomagnetic effect. For these events we compared the satellite drag
derived density with the MSISE model density. The major results can be
summarized as follows. (1) The density predicted from the MSISE models
during radiation dominated periods are comparable to the drag derived
density but the MSISE model density during strong geomagnetic storms is
significantly underestimated when the MSISE model density is compared
to the drag derived density, by about two times for the NRLMSISE-00
model. (2) The ratios of the KOMPSAT-1 (around 685 km) drag derived
density to the MSISE model density during a strong geomagnetic storm
are abruptly enhanced (up to a factor of about 8 for the MSISE-90 model
and about 3 for the NRLMSISE-00 model), which are much larger than
previous estimates from low altitude (around 400 km) satellites. (3)
There is a possible correlation between daily drag enhancement and
daily Dst variation. We note that there is a remarkable difference in
daily drag enhancement although solar and geomagnetic activities are
quite similar to each other. We suggest that such a difference should
be explained by the accumulation of solar radiation effect depending
on solar activity cycle.
Title: Investigation of CME dynamics in the LASCO field of view
Authors: Shanmugaraju, A.; Moon, Y. -J.; Cho, K. -S.; Gopalswamy,
N.; Umapathy, S.
Bibcode: 2008A&A...484..511S
Altcode:
Context: The speed-distance profile of CMEs is important for
understanding the propagation of CMEs.
Aims: Our main aim is
to study the initial speed of CMEs in the LASCO field of view and
its role in subsequent CME propagation using the acceleration-speed
profile. The secondary aim is to obtain the speed growth rate.
Methods: We considered the height-time data of 307 CMEs observed by
SOHO/LASCO during January-March 2005. To study the CME speed profile,
we used only 116 events for which there were at least 10 height-time
measurements in the LASCO field of view. Using this data, we obtained
their initial speed, extrapolated initial speed, and growth rate.
Results: The following results were found from this analysis. (i)
The initial speed obtained from the first two data points is in the
range 24-1208 km s-1, which is nearly similar to the
range of linear speed (67-920 km s-1) obtained from a
least squares fit through the entire h-t data set for each CME. (ii)
However, the initial speed or extrapolated initial speed is much
better correlated with acceleration and growth rate than the linear
speed. (iii) Nearly two thirds of the events (74/116) are found to be
accelerating. (iv) The speed growth rate is within the range -0.058
to 0.061 × 10-3 s-1, and it decreases with the
distance. (v) The final observed distance in the LASCO field of view
depends very weakly upon the initial speed, or extrapolated initial
speed whereas it depends strongly on the linear speed. The above
results demonstrate the role played by the initial speed of the CMEs.
Title: The Role of Magnetic Reconnection in the 2004 August 18
Solar Eruption
Authors: Lee, J.; Cho, K.; Bong, S.; Joshi, B.; Moon, Y.; Choe, G.
Bibcode: 2008AGUSMSP24A..01L
Altcode:
We present a morphological study of the 2004 August 18 solar flare in
which an erupting prominence is clearly visible as a bright helical
structure on (E)UV images of the Transition Region and Coronal Explorer
(TRACE) and H-alpha filtergrams of the Big Bear Solar Observatory
(BBSO). The associated coronal mass ejection (CME) is traced with white
light images of the Mouna Loa Solar Observatory (MLSO) that covers
the low corona (down to 1.08 solar radii) in order to determine its
causal relationship with the flare. Used as a signature of magnetic
reconnection is the flare radiation at hard X-rays (HXR) and microwaves,
measured by the Ramaty High Energy Solar Spectroscopic Imager
(RHESSI) and the Owens Valley Solar Array (OVSA), respectively. The
HXR- microwave emissions appear in multiple bursts located mostly
near the surface in a complicated pattern that varies from a peak to
another. It is, however, obvious that the first HXR-microwave burst
precedes the magnetic flux rising and that the prominence fully erupts
only after the HXR-microwave bursts. Therefore, the role of the first
magnetic reconnection would be tether-cutting that allows the magnetic
flux rope to rise through the overlying field. We further argue that
the subsequent reconnections play a role in adding poloidal flux to
the flux rope and thus rendering it unstable to eruption, based on
comparison of the observed morphological evolution of the prominence
with that of the kink instability model by Torok and Kleim (2005).
Title: Comparison of SOHO UVCS and MLSO MK4 Coronameter Densities
Authors: Lee, K.; Moon, Y.; Kim, K.; Lee, J.; Cho, K.; Choe, G.
Bibcode: 2008AGUSMSP51A..03L
Altcode:
We have compared the density distributions of solar corona obtained
by SOHO Ultraviolet Coronagraph Spectrometer (UVCS) and Mauna Loa
Solar Observatory (MLSO) MK4 coronameter. This is the first attempt
to compare the coronal densities estimated by the two instruments. In
the spectral data of UVCS, we have selected two emission lines (O
VI 1032~Å and 1037.6~Å), which have both radiative and collisional
components. The coronal number density is determined from the ratio
of these two components. The MK4 coronameter has a field of view
ranging from 1.08 to 2.85 solar radii. The coronal density can be
determined by inverting MLSO MK4 polarization maps. We find that the
mean electron number density in a helmet streamer observed by MK4 on
2003 April 28 is fairly consistent with that observed by UVCS. For a
coronal hole and an active region observed on 1999 October 19 and 24,
the MK4 coronal densities are close to those from the UVCS within a
factor of two; the former values are twice the latter at 1.7 solar radii
and closer to the latter at higher altitudes. Our results demonstrate
that MK4 polarization data can provide us with a coronal density
distribution in a large field of view with a time cadence of about
three minutes. We suggest that the MK4 data can be used to derive 2-D
density distributions of coronal structures and further to estimate
the heights of CME-associated type II shocks.
Title: CME Earthward Direction as an Important Geoeffectiveness
Indicator
Authors: Kim, R. -S.; Cho, K. -S.; Kim, K. -H.; Park, Y. -D.; Moon,
Y. -J.; Yi, Y.; Lee, J.; Wang, H.; Song, H.; Dryer, M.
Bibcode: 2008ApJ...677.1378K
Altcode:
Frontside halo coronal mass ejections (CMEs) are generally considered as
potential candidates for producing geomagnetic storms, but there was no
definite way to predict whether they will hit the Earth or not. Recently
Moon et al. suggested that the degree of CME asymmetries, as defined
by the ratio of the shortest to the longest distances of the CME front
measured from the solar center, be used as a parameter for predicting
their geoeffectiveness. They called this quantity a direction parameter,
D, as it suggests how much CME propagation is directed to Earth,
and examined its forecasting capability using 12 fast halo CMEs. In
this paper, we extend this test by using a much larger database (486
frontside halo CMEs from 1997 to 2003) and more robust statistical
tools (contingency table and statistical parameters). We compared the
forecast capability of this direction parameter to those of other CME
parameters, such as location and speed. We found the following results:
(1) The CMEs with large direction parameters (D >= 0.4) are highly
associated with geomagnetic storms. (2) If the direction parameter
increases from 0.4 to 1.0, the geoeffective probability rises from
52% to 84%. (3) All CMEs associated with strong geomagnetic storms
(Dst <= - 200 nT) are found to have large direction parameters
(D >= 0.6). (4) CMEs causing strong geomagnetic storms (Dst <=
- 100 nT), in spite of their northward magnetic field, have large
direction parameters (D >= 0.6). (5) Forecasting capability improves
when statistical parameters (e.g., "probability of detection—yes"
and "critical success index") are employed, in comparison with the
forecast solely based on the location and speed of CMEs. These results
indicate that the CME direction parameter can be an important indicator
for forecasting CME geoeffectiveness.
Title: Relationship between CME initial speed and magnetic helicity
of magnetic clouds
Authors: Sung, S.; Marubashi, K.; Kim, K.; Cho, K.; Moon, Y.; Chae, J.
Bibcode: 2007AGUFMSH31A0228S
Altcode:
In order to understand the relationship between solar and interplanetary
phenomena, we have examined the initial properties of coronal mass
ejections (CMEs) and magnetic helicity of magnetic clouds (MCs) for 24
CME- MC pairs. MCs are fitted with the linear force-free cylindrical
model to obtain MC parameters (orientation, size, magnetic field
magnitude, impact parameter, chirality, etc). The relative helicity
per unit length of MC is calculated by \frac{HMC}{L}=\frac{4π
B02}{α}\int0RJ12(α r)rdr. Comparing the square of CME initial speeds
(VCME2) with the magnetic helicities (HMC, we find that there is a
positive correlation between VCME2 and HMC, and the linear correlation
coefficient (CC) between the two parameters is 0.52. We obtain a better
correlation (CC=0.61) for 17 events whose impact parameter (the shortest
distance of the satellite to the MC axis normalized by MC radius)
is less than 0.5. Considering that the magnetic force in a flux rope
is intimately related to magnetic helicity, our result supports that
the magnetic force is responsible for the CME eruption. From this
result we suggest that the high speed CME is associated with large
magnetic helicity.
Title: Effect of the Interplanetary Magnetic Field on the
Thermospheric Density at High Latitude
Authors: Kwak, Y.; Richmond, A. D.; Deng, Y.; Forbes, J. M.; Kim,
K.; Cho, K.
Bibcode: 2007AGUFMSA23B..07K
Altcode:
The high-latitude thermospheric total mass density near 400 km
altitude, derived from the high-accuracy accelerometer on board the
Challenging Minisatellite Payload (CHAMP) spacecraft in November 2001
through February 2002, is statistically analyzed as a function of the
direction and strength of the interplanetary magnetic field (IMF) for
southern hemisphere. The difference densities, which are obtained by
subtracting values for zero IMF from these for nonzero IMF, show the
IMF dependence as follow: 1) Difference density for negative By shows
increase in the early morning and dawn sectors, but decrease in the
premidnight and dusk sectors. 2) For positive By it is opposite in
the signs for negative By. 3) Those for negative Bz show significant
increase in the cusp region and premidnight sector, but decrease in
the dawn sector. High-latitude thermospheric total mass densities and
variations with IMF simulated by the National Center for Atmospheric
Research Thermosphere- Ionosphere Electrodynamics General Circulation
Model (NCAR/TIEGCM), coupled with a new quantitative empirical model
of the high-latitude forcing on the thermosphere, show reasonable
agreement with CHAMP observations for the dependence of density on
the IMF direction. Using the numerical simulation, we can gain insight
into sources responsible for the thermospheric density variations. It
is suggested that high-latitude thermospheric density variations with
different IMF conditions can be strongly determined by thermospheric
winds, which vary strongly with respect to the direction of IMF. In
addition, we find that the density variations are also influenced
by the local heating associated with ionospheric current or auroral
particle precipitation, or by the local cooling, which varies with
IMF conditions.
Title: Small-scale X-ray/EUV Jets seen in Hinode XRT and TRACE
Authors: Kim, Y.; Moon, Y.; Cho, K.; Bong, S.; Park, Y.; Sakurai,
T.; Chae, J.
Bibcode: 2007AGUFMSH53A1061K
Altcode:
In this study, we present the morphological and kinematic
characteristics of three small-scale X-ray/EUV jets that are
simultaneously observed by the X-ray telescope (XRT) onboard Hinode
(Solar-B) and the TRACE. For this study, we examined all XRT movies
with a thin Al/Poly filter from 2006 October 20 to April 8 to look
for small-scale X-ray eruptions and then found 34 eruptions. Next we
took a look at the corresponding TRACE 171/195 {Å} images associated
with these X-ray eruptions. As a result, we found three simultaneous
X-ray and EUV jets and their major characteristics can be summarized
as follows : (1) They all have no association with major flares. (2)
From the comparison between XRT and TRACE observations, we found that
they have similar characteristics in terms of projected speed, lifetime,
and size. (3) Their sizes range from 4 × 105 to 5 × 105 km. (4) Their
projected speeds are estimated to be 180-310 km s-1 with an average
speed of about 250 km s- 1 (5) Their lifetimes lie in the range of 100
to 600 s. (6) From the comparison between the XRT images with the SOHO
MDI maps for two events, all they are associated with the parasitic
polarity region. These characteristics are similar to the previous
observations for X-ray jets by the Yohkoh SXT but quite different
from EUV jets associated with Hα surges. In addition, from the EIS
four spectral lines for the last event, we found blueshift (up to -64
km s-1) and redshift (up to 20 km s-1) motions as well as nonthermal
velocities ranging from 57 to 106 km s-1 at the jet footpoint. We
note a tendency : the hotter the maximum ionization temperature is,
the larger the area of blueshift region is. These characteristics
are consistent with a typical jet model that includes the magnetic
reconnection between open coronal fields and emerging magnetic fields.
Title: On the relationship between the occurrence of substorm
injections and interplanetary parameters during the declining phase
of solar cycle 23
Authors: Hwang, J.; Kim, K.; Lee, D.; Lyons, L.; Cho, K.; Park, Y.
Bibcode: 2007AGUFMSM43B1327H
Altcode:
We have examined the relationship between magnetospheric substorms
identified by LANL particle injections and daily interplanetary
parameters observed by ACE and Geotail during the second half (from
July to December) of 2003, which is the declining phase of solar cycle
23. From a statistical study of the relationship between substorms
and interplanetary parameters, the following observational results are
obtained: (1) Substorm injection occurrence is very well associated with
high-speed stream geomagnetic activity and the correlation coefficient
between daily substorm injection occurrence and daily median solar
wind speed is ~0.7, implying that solar wind speed itself strongly
modulates substorm injection; (2) The average of negative IMF Bz is not
responsible for the increase in injections with solar wind speed; and
(3) There is the evidence that IMF Bz triggering might be important to
substorm injection occurrence. In addition, we tested if the substorms
in our study are triggered with several types of northward triggering
criteria (growth phase duration time, average Bz during the growth
phase, and increase value of Bz after northward turning). We found
that the correlation coefficients between the tested IMF Bz triggers
and substorm injection occurrence range from 0.60 to 0.80, implying
that the tested types of northward turning are responsible for a large
fraction of substorms and thus are a significant contributor to the
increase in onsets with increasing solar wind speed.
Title: Hinode SP Vector Magnetogram of AR10930 and Its
Cross-Comparison with MDI
Authors: Moon, Yong-Jae; Kim, Yeon-Han; Park, Young-Deuk; Ichimoto,
Kiyoshi; Sakurai, Takashi; Chae, Jongchul; Cho, Kyung Suk; Bong,
Suchan; Suematsu, Yoshinori; Tsuneta, Saku; Katsukawa, Yukio; Shimojo,
Masumi; Shimizu, Toshifumi; Shine, Richard A.; Tarbell, Theodore D.;
Title, Alan M.; Lites, Bruce; Kubo, Masahito; Nagata, Shin'ichi;
Yokoyama, Takaaki
Bibcode: 2007PASJ...59S.625M
Altcode:
We present one Hinode Spectropolarimeter (SP) magnetogram of AR 10930
that produced several major flares. The inversion from Stokes profiles
to magnetic field vectors was made using the standard Milne-Eddington
code. We successfully applied the Uniform Shear Method for resolving
the 180° ambiguity to the magnetogram. The inversion gave very strong
magnetic field strengths (near 4500 gauss) for a small portion of area
in the umbra. Considering that the observed V-profile of 6301.5Å was
well-fitted as well as a direct estimation of the Zeeman splitting
results in 4300-4600 gauss, we think that the field strengths
should not be far from the actual value. A cross-comparison of the
Hinode SP and SOHO MDI high resolution flux densities shows that the
MDI flux density could be significantly underestimated by about a
factor of two. In addition, it has a serious negative correlation
(the so-called Zeeman saturation effect) with the Hinode SP flux
density for umbral regions. Finally, we could successfully obtain
a recalibrated MDI magnetogram that has been corrected for the
Zeeman saturation effect using not only a pair of MDI intensity and
magnetogram data simultaneously observed, but also the relationship
from the cross-comparison between the Hinode SP and MDI flux densities.
Title: Small-Scale X-Ray/EUV Jets Seen in Hinode XRT and TRACE
Authors: Kim, Yeon-Han; Moon, Young-Jae; Park, Young-Deuk; Sakurai,
Takashi; Chae, Jongchul; Cho, Kyung Suk; Bong, Su-Chan
Bibcode: 2007PASJ...59S.763K
Altcode:
We present the morphological and kinematic characteristics of three
small-scale X-ray/EUV jets simultaneously observed by the Hinode
XRT and the TRACE. For this, we examined all XRT movies with a thin
Al/Poly filter from 2006 October 20 to 2007 April 8, and then found
34 small-scale eruptions. We next took a look at the corresponding
TRACE 171/195Å images associated with the eruptions. As a result,
we found three simultaneous X-ray and EUV jets. For two different
bands, they have similar characteristics in terms of the projected
speed (90-310kms-1), lifetime (100-2000s), and size
(1.1-5×105km). These characteristics are similar to the
previous results by the Yohkoh SXT, but are quite different from EUV
jets associated with Hα surges. From the EUV Imaging Spectrometer,
four spectral lines for the last event, we found blueshift (up to
-64kms-1) and redshift (up to 20kms-1) motions as
well as nonthermal velocities ranging from 57 to 106kms-1
at the jet footpoint. We note a tendency: the hotter the maximum
ionization temperature is, the smaller the area of blueshift region
is. These characteristics are consistent with a typical jet model
that includes the magnetic reconnection between open coronal fields
and emerging magnetic fields.
Title: The Eruption from a Sigmoidal Solar Active Region on 2005
May 13
Authors: Liu, Chang; Lee, Jeongwoo; Yurchyshyn, Vasyl; Deng, Na; Cho,
Kyung-suk; Karlický, Marian; Wang, Haimin
Bibcode: 2007ApJ...669.1372L
Altcode: 2007arXiv0707.2240L
This paper presents a multiwavelength study of the M8.0 flare and
its associated fast halo CME that originated from a bipolar NOAA
AR 10759 on 2005 May 13. The source active region has a conspicuous
sigmoid structure at the TRACE 171 Å channel as well as in the SXI
soft X-ray images, and we mainly concern ourselves with the detailed
process of the sigmoid eruption, as evidenced by the multiwavelength
data ranging from Hα, WL, EUV/UV, radio, and hard X-rays (HXRs). The
most important finding is that the flare brightening starts in the
core of the active region earlier than that of the rising motion of
the flux rope. This timing clearly addresses one of the main issues in
the magnetic eruption onset of sigmoid, namely, whether the eruption
is initiated by an internal tether cutting to allow the flux rope
to rise upward, or a flux rope rises due to a loss of equilibrium to
later induce tether cutting below it. Our high time cadence SXI and Hα
data show that the first scenario is relevant to this eruption. As in
other major findings, we have the RHESSI HXR images showing a change
of the HXR source from a confined footpoint structure to an elongated
ribbon-like structure after the flare maximum, which we relate to the
sigmoid-to-arcade evolution. The radio dynamic spectrum shows a type II
precursor that occurred at the time of expansion of the sigmoid and a
drifting pulsating structure in the flare rising phase in HXRs. Finally,
type II and III bursts are seen at the time of maximum HXR emission,
simultaneous with the maximum reconnection rate derived from the flare
ribbon motion in UV. We interpret these various observed properties
with the runaway tether-cutting model proposed by Moore et al. in 2001.
Title: Magnetic Field Strength in the Solar Corona from Type II
Band Splitting
Authors: Cho, K. -S.; Lee, J.; Gary, D. E.; Moon, Y. -J.; Park, Y. D.
Bibcode: 2007ApJ...665..799C
Altcode:
The phenomenon of band splitting in type II bursts can be a unique
diagnostic for the magnetic field in the corona, which is, however,
inevitably sensitive to the ambient density. We apply this diagnostic
to the CME-flare event on 2004 August 18, for which we are able to
locate the propagation of the type II burst and determine the ambient
coronal electron density by other means. We measure the width of the
band splitting on a dynamic spectrum of the bursts observed with the
Green Bank Solar Radio Burst Spectrometer (GBSRBS), and convert it
to the Alfvén Mach number under the Rankine-Hugoniot relation. We
then determine the Alfvén speed and magnetic field strength using the
coronal background density and shock speed measured with the MLSO/MK4
coronameter. In this way we find that the shock compression ratio is
in the range of 1.5-1.6, the Alfvénic Mach number is 1.4-1.5, the
Alfvén speed is 550-400 km s-1, and finally the magnetic
field strength decreases from 1.3 to 0.4 G while the shock passes
from 1.6 to 2.1 Rsolar. The magnetic field strength derived
from the type II spectrum is finally compared with the potential field
source surface (PFSS) model for further evaluation of this diagnostic.
Title: Drag Effect of Kompsat-1 During Strong Solar and Geomagnetic
Activity
Authors: Park, J.; Moon, Y. -J.; Kim, K. -H.; Cho, K. -S.; Kim,
H. -D.; Kim, Y. -H.; Park, Y. -D.; Yi, Y.
Bibcode: 2007JASS...24..125P
Altcode:
In this paper, we analyze the orbital variation of the KOrea
Multi-Purpose SATellite-1(KOMPSAT-1) in a strong space environment due
to satellite drag by solar and geomagnetic activities. The satellite
drag usually occurs slowly, but becomes serious satellite drag when the
space environment suddenly changes via strong solar activity like a big
flare eruption or coronal mass ejections(CMEs). Especially, KOMPSAT-1
as a low earth orbit satellite has a distinct increase of the drag
acceleration by the variations of atmospheric friction. We consider
factors of solar activity to have serious effects on the satellite drag
from two points of view. One is an effect of high energy radiation when
the flare occurs in the Sun. This radiation heats and expands the upper
atmosphere of the Earth as the number of neutral particles is suddenly
increased. The other is an effect of Joule and precipitating particle
heating caused by current of plasma and precipitation of particles
during geoma! gnetic storms by CMEs. It also affects the density
of neutral particles by heating the upper atmosphere. We investigate
the satellite drag acceleration associated with the two factors for
five events selected based on solar and geomagnetic data from 2001 to
2002. The major results can be summarized as follows. First, the drag
acceleration started to increase with solar EUV radiation with the best
cross-correlation (r = 0.92) for 1 day delayed F10.7. Second, the drag
acceleration and Dst index have similar patterns when the geomagnetic
storm is dominant and the drag acceleration abruptly increases during
the strong geomagnetic storm. Third, the background variation of the
drag accelerations is governed by the solar radiation, while their short
term (less than a day) variations is governed by geomagnetic storms.
Title: Prediction of the 1-AU arrival times of CME-associated
interplanetary shocks: Evaluation of an empirical interplanetary
shock propagation model
Authors: Kim, K. -H.; Moon, Y. -J.; Cho, K. -S.
Bibcode: 2007JGRA..112.5104K
Altcode: 2007JGRA..11205104K
The traveltimes of interplanetary (IP) shocks at 1 AU associated with
coronal mass ejections (CMEs) can be predicted by the empirical shock
arrival (ESA) model of Gopalswamy et al. [2004] based on a constant IP
acceleration. We evaluate the ESA model using 91 IP shocks identified
from sudden commencement (SC)/sudden impulse (SI) on the Earth and by
examining the solar wind data from the ACE and WIND satellites during
the period of 1997 to 2002. Out of 91 CME-IP shock pairs, 55 events
(∼60%) were predicted within ±12 hours from the ESA model. The ESA
model predicted ∼59% (43 out of 73) of the events during solar maximum
(1999-2002) and ∼67% (12 out of 18) of the events during solar minimum
(1997-1998) within ±12 hours from the predicted curve. Comparing
the predicted (Tmod) and observed (Tobs) shock
arrival times during solar maximum, we find that the deviations (ΔT =
Tobs - Tmod) of shock arrival times from the ESA
model strongly correlate with the CME initial speeds (VCME)
(linear correlation, r = 0.77). Such a strong correlation indicates that
the constant IP acceleration in the ESA model is not reasonably well
applied for all VCME. From the linear regression analysis,
we obtain a linear fit to the relationship (r = -0.62) between IP
shock traveltime T (in hours) and VCME (in kilometer
per second) during the solar maximum, which can be expressed as T =
76.86 - 0.02VCME. In addition, we find that the IP shocks
associated with the fast CMEs corresponding to strong SC/SI events
have short traveltimes compared with other fast CMEs and that there
is a negative correlation between the SC/SI strength and the IP shock
traveltime. We suggest that this negative correlation is due to not
only the VCME but also the CME mass/density and discuss the
influence of the mass/density of CME on the arrival time of IP shock
at 1 AU.
Title: Cosmic-ray positron fraction measurement from 1 to 30 GeV
with AMS-01
Authors: AMS-01 Collaboration; Aguilar, M.; Alcaraz, J.; Allaby, J.;
Alpat, B.; Ambrosi, G.; Anderhub, H.; Ao, L.; Arefiev, A.; Azzarello,
P.; Baldini, L.; Basile, M.; Barancourt, D.; Barao, F.; Barbier,
G.; Barreira, G.; Battiston, R.; Becker, R.; Becker, U.; Bellagamba,
L.; Béné, P.; Berdugo, J.; Berges, P.; Bertucci, B.; Biland, A.;
Blasko, S.; Boella, G.; Boschini, M.; Bourquin, M.; Brocco, L.; Bruni,
G.; Buénerd, M.; Burger, J. D.; Burger, W. J.; Cai, X. D.; Camps,
C.; Cannarsa, P.; Capell, M.; Cardano, F.; Casadei, D.; Casaus, J.;
Castellini, G.; Chang, Y. H.; Chen, H. F.; Chen, H. S.; Chen, Z. G.;
Chernoplekov, N. A.; Chiueh, T. H.; Cho, K.; Choi, M. J.; Choi, Y. Y.;
Cindolo, F.; Commichau, V.; Contin, A.; Cortina-Gil, E.; Cristinziani,
M.; Dai, T. S.; Delgado, C.; Difalco, S.; Djambazov, L.; D'Antone,
I.; Dong, Z. R.; Emonet, P.; Engelberg, J.; Eppling, F. J.; Eronen,
T.; Esposito, G.; Extermann, P.; Favier, J.; Fiandrini, E.; Fisher,
P. H.; Flügge, G.; Fouque, N.; Galaktionov, Yu.; Gast, H.; Gervasi,
M.; Giusti, P.; Grandi, D.; Grimm, O.; Gu, W. Q.; Hangarter, K.;
Hasan, A.; Hermel, V.; Hofer, H.; Hungerford, W.; Jongmanns, M.;
Karlamaa, K.; Karpinski, W.; Kenney, G.; Kim, D. H.; Kim, G. N.;
Kim, K. S.; Kim, M. Y.; Klimentov, A.; Kossakowski, R.; Kounine,
A.; Koutsenko, V.; Kraeber, M.; Laborie, G.; Laitinen, T.; Lamanna,
G.; Lanciotti, E.; Laurenti, G.; Lebedev, A.; Lechanoine-Leluc, C.;
Lee, M. W.; Lee, S. C.; Levi, G.; Liu, C. L.; Liu, H. T.; Lu, G.;
Lu, Y. S.; Lübelsmeyer, K.; Luckey, D.; Lustermann, W.; Maña, C.;
Margotti, A.; Mayet, F.; McNeil, R. R.; Meillon, B.; Menichelli, M.;
Mihul, A.; Mujunen, A.; Oliva, A.; Olzem, J.; Palmonari, F.; Park,
H. B.; Park, W. H.; Pauluzzi, M.; Pauss, F.; Perrin, E.; Pesci, A.;
Pevsner, A.; Pilo, F.; Pimenta, M.; Plyaskin, V.; Pojidaev, V.; Pohl,
M.; Produit, N.; Rancoita, P. G.; Rapin, D.; Raupach, F.; Ren, D.;
Ren, Z.; Ribordy, M.; Richeux, J. P.; Riihonen, E.; Ritakari, J.;
Ro, S.; Roeser, U.; Rossin, C.; Sagdeev, R.; Santos, D.; Sartorelli,
G.; Sbarra, C.; Schael, S.; Schultz von Dratzig, A.; Schwering, G.;
Seo, E. S.; Shin, J. W.; Shoumilov, E.; Shoutko, V.; Siedenburg,
T.; Siedling, R.; Son, D.; Song, T.; Spinella, F.; Steuer, M.; Sun,
G. S.; Suter, H.; Tang, X. W.; Ting, Samuel C. C.; Ting, S. M.;
Tornikoski, M.; Torsti, J.; Trümper, J.; Ulbricht, J.; Urpo, S.;
Valtonen, E.; Vandenhirtz, J.; Velikhov, E.; Verlaat, B.; Vetlitsky,
I.; Vezzu, F.; Vialle, J. P.; Viertel, G.; Vité, D.; von Gunten,
H.; Waldmeier Wicki, S.; Wallraff, W.; Wang, B. C.; Wang, J. Z.;
Wiik, K.; Williams, C.; Wu, S. X.; Xia, P. C.; Xu, S.; Yan, J. L.;
Yan, L. G.; Yang, C. G.; Yang, J.; Yang, M.; Ye, S. W.; Xu, Z. Z.;
Zhang, H. Y.; Zhang, Z. P.; Zhao, D. X.; Zhou, Y.; Zhu, G. Y.; Zhu,
W. Z.; Zhuang, H. L.; Zichichi, A.; Zimmermann, B.; Zuccon, P.
Bibcode: 2007PhLB..646..145A
Altcode: 2007astro.ph..3154A
A measurement of the cosmic ray positron fraction
e/(e+e) in the energy range of 1 30
GeV is presented. The measurement is based on data taken by the AMS-01
experiment during its 10 day Space Shuttle flight in June 1998. A proton
background suppression on the order of 106 is reached by
identifying converted bremsstrahlung photons emitted from positrons.
Title: A study of CME and type II shock kinematics based on coronal
density measurement
Authors: Cho, K. -S.; Lee, J.; Moon, Y. -J.; Dryer, M.; Bong, S. -C.;
Kim, Y. -H.; Park, Y. D.
Bibcode: 2007A&A...461.1121C
Altcode:
Aims:The aim of this paper is to determine location and speed of
a coronal shock from a type II burst spectrum without relying on
any coronal density model, and to use the result to discuss the
relationship between the type II burst and Coronal Mass Ejection
(CME).
Methods: This study is made for the 2004 August 18
solar eruption observed by Green Bank Solar Radio Burst Spectrometer
(GBSRBS) and a limb CME/streamer simultaneously detected by Mauna Loa
Solar Observatory (MLSO) MK4 coronameter. We determine the background
density distribution over the area of interest by inverting the
MLSO MK4 polarization map taken just before the CME onset. Using
the two-dimensional density distribution and the type II emission
frequencies, we calculate the type II shock heights along several radial
directions selected to encompass the entire position angles of the
CME. We then compare these emission heights with those of the CME to
determine at which position angle the type II burst propagated. Along
the most plausible position angle, we finally determine the height and
speed of the shock as functions of time.
Results: It turns out
that the type II emission height calculated along a southern streamer
best agrees to the observed height of the CME flank. Along this region,
both the shock and CME moved at a speed ranging from 800 to 600 km
{s}-1. We also found that the streamer boundary already had
enhanced density compared to other parts before the CME and formed a
low Alfvénic region.
Conclusions: .We therefore conclude that
the type II burst was generated at the interface of the CME flank and
the streamer, as favorable for the shock formation.
Title: A Statistical Study of Streamer-Associated Coronal Mass
Ejections
Authors: Moon, Y. J.; Kim, Jin-Sug; Kim, Y. H.; Cho, K. S.; Bong,
Su-Chan; Park, Y. D.
Bibcode: 2006JKAS...39..139M
Altcode:
No abstract at ADS
Title: Repetitive substorms caused by Alfvénic waves of the
interplanetary magnetic field during high-speed solar wind streams
Authors: Lee, D. -Y.; Lyons, L. R.; Kim, K. C.; Baek, J. -H.; Kim,
K. -H.; Kim, H. -J.; Weygand, J.; Moon, Y. -J.; Cho, K. -S.; Park,
Y. D.; Han, W.
Bibcode: 2006JGRA..11112214L
Altcode:
Substorms sometimes occur repetitively with a period of ∼1-4 hours. In
this paper we examine repetitive substorms, identified using particle
injections and positive H bays on the nightside, that we find to
occur during corotating high-speed streams associated with coronal
holes. The high-speed streams often last for several days and are
accompanied by large amplitude Alfvén waves of the interplanetary
magnetic field (IMF). We find that repetitive substorms occur every
∼1-4 hours, regardless of the solar cycle phase, whenever the
Earth's magnetosphere is impinged by these high-speed streams. We
further find that a significant number of these substorms are
associated with repetitive northward turnings of the Alfvénic IMF,
each northward turning preceded by weakly-to-moderately southward
IMF, i.e., Bz ∼ -3.6 nT for ∼29 min on the average. We
present eight example intervals where most of the repetitive substorms
were associated with a northward turning. Statistically, for 63.5%
of 312 substorms we are able to identify a reasonable association
with a northward turning. While limitations of the Weimer-mapped IMF
used here and the spatial structure of the Alfvénic IMF prevent us
from estimating a precise figure for the percentage of IMF triggered
substorms, our results indicate that many of the repetitive substorms
are likely due to repetitive triggering by the Alfvénic IMF.
Title: Development of KASI Solar Imaging Spectrograph
Authors: Kim, Y. -H.; Moon, Y. -J.; Cho, K. -S.; Park, Y. -D.; Choi,
S. -H.; Jang, B. -H.; Kim, S.
Bibcode: 2006PKAS...21...51K
Altcode:
We have successfully developed the KASI (Korean Astronomy and Space
Science Institute) Solar Imaging Spectrograph (KSIS), which has been
originally upgraded from the KASI solar spectrograph that was able to
record solar spectra for a given slit region and to inspect the response
function of narrow band filters. A prototype KSIS was developed in
2004 by using a scanning mirror in front of the spectrograph slit and
a SBIG ST-8XE CCD camera. Its main disadvantage is that it took a long
time (about 13 minutes) to scan a whole active region. In this work,
we have upgraded the KSIS by installing a much faster Dalsa 1M15 CCD
camera, which gives a data acquisition time of about 2.5 minutes. The
software for KSIS was also improved for the new CCD camera on the basis
of component-based development method. We have successfully made a
test observation for a simple and small active region (AR10910) using
the improved KSIS system. Our observations show that H-alpha images
for several wavelengths have typical features in a sunspot as well as
a H-alpha centerline image is quite similar to a BBSO H-alpha image,
demonstrating the capability of the KSIS system.
Title: X-ray plasma ejections associated with coronal type II shocks
Authors: Shanmugaraju, A.; Moon, Y. -J.; Kim, Y. -H.; Cho, K. -S.;
Dryer, M.; Umapathy, S.
Bibcode: 2006A&A...458..653S
Altcode:
Context: .Recent observations suggest that X-ray plasma ejections
can drive coronal shocks and metric type IIs that are also generated
in close association with the X-ray erupting features.
Aims:
.The physical relationship between the plasma ejections and metric
type II radio bursts are studied by analyzing the characteristics of
ejecta and type IIs.
Methods: .We present the first comprehensive
analysis of a set of 18 events of X-ray plasma ejections associated
with coronal shocks inferred from metric type II radio bursts. For
this study, we have utilized a list of 137 limb X-ray plasma ejection
events and multi-wavelength observations from GOES X-ray, Yohkoh SXT,
SOHO/LASCO, and SOHO/EIT.
Results: .(i) type IIs are reported
only for about 15% of the 137 limb ejections; (ii) there exists a
close temporal relationship among the starting time of type IIs,
the hard X-ray flare peak, and the ejecta time; (iii) there exist
negative correlations between X-ray loop length and starting frequency,
and between the ejecta height and starting frequency of type IIs; (iv)
the type II formation height computed using the starting frequency and
1 × Newkirk electron density model is in close association with or
above the height of X-ray ejecta; and (v) while there is no correlation
between the speeds of type II and ejecta, there seems to be a weak
correlation between the speeds of type II and CME.
Conclusions:
. Though the results suggest that some type IIs are generated in close
association with the X-ray erupting features, it is not likely that
X-ray plasma ejections are the main drivers of all coronal shocks and
metric type II radio bursts due to the absence of correlation between
both speeds and mostly sub-Alfenic speeds of the ejections.
Title: Novel Internal Multi-Antenna Configuration Employing Folded
Dipole Elements for Notebook PC
Authors: Okano, Y.; Cho, K.
Bibcode: 2006ESASP.626E..71O
Altcode: 2006ecap.confE..71O
No abstract at ADS
Title: Fractal Dimension and Maximum Sunspot Number in Solar Cycle
Authors: Kim, R. -S.; Yi, Y.; Cho, K. -S.; Moon, Y. -J.; Kim, S. W.
Bibcode: 2006JASS...23..227K
Altcode:
The fractal dimension is a quantitative parameter describing the
characteristics of irregular time series. In this study, we use
this parameter to analyze the irregular aspects of solar activity
and to predict the maximum sunspot number in the following solar
cycle by examining time series of the sunspot number. For this,
we considered the daily sunspot number since 1850 from SIDC (Solar
Influences Data analysis Center) and then estimated cycle variation
of the fractal dimension by using Higuchi's method. We examined the
relationship between this fractal dimension and the maximum monthly
sunspot number in each solar cycle. As a result, we found that there
is a strong inverse relationship between the fractal dimension and the
maximum monthly sunspot number. By using this relation we predicted the
maximum sunspot number in the solar cycle from the fractal dimension
of the sunspot numbers during the solar activity increasing phase. The
successful prediction is proven by a good correlation (r=0.89) between
the observed and predicted maximum sunspot numbers in the solar cycles.
Title: A Near-simultaneous Observation of X-ray Plasma Ejection,
Coronal Mass Ejection, and Type II Radio Burst
Authors: Kim, Y. -H.; Moon, Y. -J.; Cho, K. -S.; Cho, K. -S.; Bong,
S. -C.; Park, Y. -D.
Bibcode: 2006IAUJD...3E..85K
Altcode:
We report on the first near-simultaneous observation of X-ray plasma
ejection (XPE), type II solar radio burst, and coronal mass ejection
(CME) on 1999 October 26. First, an XPE was observed from 21:12 UT to
21:23 UT in the Yohkoh/ SXT field of view (1.1 to 1.4 solar radii). The
XPE was initially accelerated and then constantly propagated with
a speed of about 350 km/s. Second, a type II solar radio burst was
observed at 21:30 UT by the Culgoora solar radio spectrograph. The burst
started at the height of about 1.5 solar radii which is estimated from
its starting frequency assuming the one-fold Newkirk coronal density
model. From the frequency drift rate of the burst, the propagation
speed is estimated to be about 400 km/s. Third, the associated CME was
observed by the Mauna Loa Mk 4 coronameter (1.2 to 2.8 solar radii). The
CME front was identified at 21:20 UT and its speed was 500 km/s
(around 2 solar radii) at the type II starting time. By comparing these
three phenomena, we found that (1) there is a remarkable difference
(0.4 solar radii) between the CME front and the XPE front at 21:23 UT,
(2) the type II formation height is not consistent with the CME front
but with the trajectory extrapolated from the XPE front, (3) three
speeds are comparable with one another. Regarding the type II origin,
our results suggest two possibilities: coronal shock generation by
the XPE front or the CME flank.
Title: Sigmoid, Type II Precursor, and Coronal Mass Ejection
Authors: Lee, Jeongwoo; Liu, C.; Cho, K.; Gary, D. E.; Yurchyshyn,
V.; Deng, N.; Wang, H.
Bibcode: 2006SPD....37.0907L
Altcode: 2006BAAS...38..236L
The 2005 May 13 flare occurred in the sigmoidal active region, NOAA
10759, and its time dependent change on the TRACE, EIT, and SXI images
suggests an eruption process as envisioned by the runaway tether-cutting
model. However, the onset of the eruption in the low corona and the
final explosion of the magnetic field in the high corona are not
directly observable at these wavelengths and we infer them indirectly
from the radio data obtained with the Owens Valley Solar Array (OVSA),
Green Bank Solar Radio Burst Spectrometer (GBSRBS), PHOENIX-spectrograph
of ETH Zurich, and the Potsdam-Tremsdorf Spectrograph. The Potsdam
spectrograph shows a so-called Type II Precursor in the early phase
of loop expansion, indicating a coronal shock formed near the flare
site. The GBSRBS spectra show a type III burst followed by type II
bursts in the maximum phase, which implies opening of field lines
and strong shock formation in the high corona. Finally, the radio
pulsations are detected on the OVSA and PHOENIX spectrographs, which
we interpret as due to the magnetic loop oscillation as a dynamic
response to the mass ejection. These radio data along with the EUV
and X-ray images are used to infer the runaway tether-cutting process
during this event in all coronal heights.This work is supported by
NSF/SHINE grant ATM-0548952 and NSF grant AST-0307670 to NJIT.
Title: New Criteria for Geoeffective CMEs
Authors: Kim, Rok-Soon; Cho, K.; Moon, Y.; Yi, Y.; Lee, J.; Kim, Y.;
Dryer, M.; Park, Y.
Bibcode: 2006SPD....37.0814K
Altcode: 2006BAAS...38R.232K
For a purpose of space weather forecast, we searched for the criteria
for selecting geoeffective CMEs (Dst <-50nT). Since the front side
halo CMEs are generally considered as strong candidates for geomagnetic
storms, we selected, out of 7742 SOHO/LASCO CMEs from 1997 to 2003, 293
front side halo (including partial halo) CMEs, and examined how their
geoeffectiveness depends on their speed, V, Source region location,
L, and the earthward direction parameter. The direction parameter is
defined as the ratio of distance between the shorter CME front and the
solar center to that of the longer CME front. We first examined how the
probability of geoeffective CMEs depends on the speed and location. It
is found that the probability is larger than the mean ( 39%, 114/293)
when the CME occurs at 0<L≤+30 with V<800km/s or -30<L≤+60
with V≥800km/s. We then examined how this probability can improve by
including the direction parameter. As a result we found that even the
limb CMEs can possibly be geoeffective as far as direction is greater
than 0.70. On the other hand, if this direction parameter is small
(<0.15), even the disk CMEs could not drive storms. We further
produced the contingency tables that are used to estimate various
statistical parameters including the Probability Of Detection yes (PODy)
and Critical Success Index (CSI). When we predict the geoeffective
CMEs only using their velocities and locations, the PODy and CSI are
estimated to be 64% and 42%, respectively. If the direction parameter
was included in the prediction, we could improve the PODy and CSI to
70% and 45%, respectively. The criteria that we found in this study can
lead to a more accurate forecast of geomagnetic storms with information
of CME characteristics only, which thus allows an earlier warning than
other existing methods.
Title: Coronal Breakout Seen in LASCO C1: Does Breakout Precede or
Follow Solar Eruption?
Authors: Bong, Su-Chan; Moon, Y.; Cho, K.; Kim, Y.; Park, Y.; Choe, G.
Bibcode: 2006SPD....37.2504B
Altcode: 2006BAAS...38..252B
We report a direct SOHO LASCO C1 observation of low coronal ``magnetic
breakout'' that occurred during the coronal mass ejection (CME) on
1998 March 23. The LASCO C1 images show that a slowly expanding, small
coronal loop on the northeastern limb erupted, becoming a CME with
the typical three-part structure (core, void, and front). Just after
the CME front went out of the C1 field of view (about 2 solar radii),
a wedgelike open structure is clearly formed. From this observation,
together with Yohkoh SXT and SOHO MDI images, we inferred the change
of the coronal magnetic field configuration during the eruption,
which shows a morphological consistency with the breakout CME
model. However, our observation shows that the initial acceleration
(∼ 100 m s-2) of the CME front began about 1 hr before
the apparent field opening. This observation disagrees with the CME
initiation mechanism of the breakout model. The following second
acceleration (∼ 300 m s-2) was, meanwhile, coincident
with the time of coronal breakout. We note that the observed eruption
progressed in four distinct phases: a slow rise of loop structures,
the initial acceleration of the CME, the magnetic breakout and second
acceleration, and the CME propagation at almost-constant speed.
Title: The Eruption from a Sigmoid Active Region on 2005 May 13
Authors: Liu, Chang; Lee, J.; Yurchyshyn, V.; Cho, K.; Deng, N.;
Gary, D. E.; Wang, H.
Bibcode: 2006SPD....37.0821L
Altcode: 2006BAAS...38..234L
A sigmoidal structure of active regions has been of interest as is
believed to lead to magnetic eruption. We found from TRACE EUV images
that NOAA AR 10759 exhibited a typical sigmoid shape just before the
M8.0 flare and a fast halo CME on 2005 May 13, and reduced to a more
confined arcade after the eruption. We have thus examined these time
dependent changes during the flare by utilizing a multiwavelength
data set: EUV (TRACE, EIT), soft X-rays (SXI), H-alpha (BBSO,ISOON),
radio spectra (OVSA, Potsdam-Tremsdorf, GBSRBS, Phoenix, RSTN),
and CME (LASCO). Several similarities of this event with the runaway
tether-cutting scenario elaborated by Moore et al. (2001) has been
found. Before the maximum phase, the flare brightening first occurred in
the core of the active region, and then two elbows in the outer region
gradually expanded, which we compare to the tether-cutting in the
sigmoid center and the ejective eruption, respectively. At the flare
maximum, the large-scale disturbances such as Moreton waves, type II,
and III radio bursts were observed, which we suggest as evidence for
the blow-out of the envelope field and particle acceleration. Finally
the flare arcade formed along the neutral line as the opened legs of
the envelop field reconnect with each other. This dataset therefore
supports the idea that the eruption may start in the sheared core
field and proceeds outward with the rising plasmoid via the runaway
tether-cutting reconnection and finally becomes a CME.This work is
supported by NSF/SHINE grant ATM-0548952, NSF grant ATM-0536921,
and NASA grant NNG0-4GJ51G.
Title: Coronal mass ejection geoeffectiveness depending on field
orientation and interplanetary coronal mass ejection classification
Authors: Kang, Seung-Mi; Moon, Y. -J.; Cho, K. -S.; Kim, Yeon-Han;
Park, Y. D.; Baek, Ji-Hye; Chang, Heon-Young
Bibcode: 2006JGRA..111.5102K
Altcode: 2006JGRA..11105102K
In this study, we have examined the coronal mass ejection (CME)
geoeffectiveness characterized by Dst ≤ -50 nT according to the
field orientation (N or S) in a CME source region and its dependence
on interplanetary CME (ICME) classification (magnetic clouds or
ejecta). We first considered 133 CME-ICME pairs (1996 to 2001)
whose CME source locations are identified by SOHO Large-Angle
Spectrometric Coronograph (SOHO/LASCO) and extreme ultraviolet
imaging telescope (SOHO/EIT) data. Then we identified the shapes (S
or Inverse-S) of the X-ray sigmoids associated with 63 of these CMEs
using Yohkoh/Soft X-Ray Telescope (SXT) data. To determine the field
orientation in the sigmoids, we applied the coronal flux rope (CFR)
model and the force-free field (FFF) model to these 63 sigmoids using
SOHO/Michelson Doppler Imager (MDI) images. We present the results in
contingency tables, classified according to solar field orientation
and geomagnetic storm strength/occurrence. We found that (1) the
prediction of geomagnetic storms (Dst ≤ -50 nT) based on the CFR
model is much better than that on the FFF model, (2) the prediction
for magnetic clouds (MCs) is much better than that for ejecta (EJ),
which implies that the field orientation of the MCs is well conserved
through the heliosphere, and (3) for about 86% of the magnetic clouds,
the directions of their leading fields are consistent with those in the
CME source regions. Our results support the findings that the southward
orientations of the magnetic field in the CME source regions plays an
important role in the production of geomagnetic storms.
Title: Origin of Coronal Shocks without Mass Ejections
Authors: Shanmugaraju, A.; Moon, Y. -J.; Cho, K. -S.; Dryer, M.;
Umapathy, S.
Bibcode: 2006SoPh..233..117S
Altcode:
We present an analysis of all the events (around 400) of coronal
shocks for which the shock-associated metric type IIs were observed by
many spectrographs during the period April 1997- December 2000. The
main objective of this analysis is to give evidence for the type IIs
related to only flare-blast waves, and thus to find out whether there
are any type II-associated coronal shocks without mass ejections. By
carefully analyzing the data from multi-wavelength observations (Radio,
GOES X-ray, Hα, SOHO/LASCO and SOHO/EIT-EUV data), we have identified
only 30 events for which there were actually no reports of CMEs. Then
from the analysis of the LASCO and EIT running difference images, we
found that there are some shocks (nearly 40%, 12/30) which might be
associated with weak and narrow mass ejections. These weak and narrow
ejections were not reported earlier. For the remaining 60% events
(18/30), there are no mass ejections seen in SOHO/LASCO. But all of
them are associated with flares and EIT brightenings. Pre-assuming
that these type IIs are related to the flares, and from those flare
locations of these 18 cases, 16 events are found to occur within the
central region of the solar disk (longitude ≤45^∘). In this case,
the weak CMEs originating from this region are unlikely to be detected
by SOHO/LASCO due to low scattering. The remaining two events occurred
beyond this longitudinal limit for which any mass ejections would have
been detected if they were present. For both these events, though there
are weak eruption features (EIT dimming and loop displacement) in the
EIT images, no mass ejection was seen in LASCO for one event, and a CME
appeared very late for the other event. While these two cases may imply
that the coronal shocks can be produced without any mass ejections,
we cannot deny the strong relationship between type IIs and CMEs.
Title: Drag effect of KOMPSAT-1 spacecraft during strong solar and
geomagnetic activity
Authors: Park, J. -Y.; Moon, Y. -J.; Cho, K. -S.; Kim, H. -D.; Kim,
K. -H.; Kim, Y. -H.; Park, Y. -D.; Yi, Y.
Bibcode: 2006cosp...36.2254P
Altcode: 2006cosp.meet.2254P
We have examined the drag effect of the Korea Multi-Purpose Satellite-1
KOMPSAT-1 during strong solar and geomagnetic activities There are
two major mechanisms to induce satellite drags the heating by solar
EUV radiation characterized by F10 7 and the heating by joule heating
via particle precipitation during geomagnetic storms characterized by
ap Dst and Polar Cap index In order to examine these effects we select
five events dominated by the radiation effect and or the particle effect
In addition we compared the density derived from the drag acceleration
equation with that based on the MSISE-90 empirical atmospheric model
The major results can be summarized as follows 1 The satellite drag
acceleration started simultaneously with the increase of solar EUV
radiation such as solar flares and then has the best correlation with
the 1 day delayed F10 7 2 We found that there were five abrupt changes
of drag acceleration that were nearly coincident with geomagnetic
storms 3 While the background variation of the drag acceleration is
governed by solar radiation their short term about a day variation by
strong geomagnetic storms 4 The density from the MSISE-90 empirical
atmospheric density model is similar to that from the drag acceleration
equation during the radiation dominated period but significantly up
to a factor of 8 different during the strong geomagnetic storms
Title: Direct Observation of Low Coronal Breakout: Does Breakout
Precede or Follow Solar Eruption?
Authors: Bong, Su-Chan; Moon, Y. -J.; Cho, K. -S.; Kim, Yeon-Han;
Park, Y. D.; Choe, G. S.
Bibcode: 2006ApJ...636L.169B
Altcode:
In this Letter, we report a direct SOHO LASCO C1 observation of
low coronal ``magnetic breakout'' that occurred during the coronal
mass ejection (CME) on 1998 March 23. The LASCO C1 images show
that a slowly expanding, small coronal loop on the northeastern
limb erupted, becoming a CME with the typical three-part structure
(core, void, and front). Just after the CME front went out of the
C1 field of view (about 2 solar radii), a wedgelike open structure
is clearly formed. From this observation, together with Yohkoh SXT
and SOHO MDI images, we inferred the change of the coronal magnetic
field configuration during the eruption, which shows a morphological
consistency with the breakout CME model. However, our observation shows
that the initial acceleration (~100 m s-2) of the CME front
began about 1 hr before the apparent field opening. This observation
disagrees with the CME initiation mechanism of the breakout model. We
note that the observed eruption progressed in four distinct phases:
a slow rise of loop structures, the initial acceleration of the CME,
the magnetic breakout and second acceleration, and the CME propagation
at almost-constant speed.
Title: Toward an empirical model of the CME-storm relationship
Authors: Moon, Y. -J.; Cho, K. -S.; Kim, R. -S.; Kang, S. -M.; Kim,
Y. -H.; Kim, K. -H.; Bong, S. -C.; Park, Y. D.
Bibcode: 2006cosp...36.2201M
Altcode: 2006cosp.meet.2201M
Solar and Space Weather group in KASI has been examining the physcial
characteristics of geoeffective CMEs in order to develop an empirical
model of the CME-storm relationship First we have presented the
probablities of CME geoeffectiveness depending its solar surface
location speed and earthward direction using front-side SOHO LASCO
halo CMEs from 1997 to 2003 Second we have examined the relationship
between several CME physical parameters e g earthward direction density
mass and its associated geomagnetic storm for very fast halo CMEs
In particular we suggest a new direction parameter that is directly
observable from coronagraph observations Third we have examined the
relationship between the field orientation in a CME source region
and a geomagnetic storm using a coronal flux rope model as well as
its dependence on ICME classification magnetic cloud or ejecta Major
results are as follows 1 The most probably areas whose geoeffectiveness
fraction is larger than the mean probability 0 4 are 0 L 30 deg for
slower speed CMEs 800km s and -30 L 60 deg for faster CMEs 800 km s 2
The CME direction and its column density have much better correlations
with the Dst index than other parameters for very fast halo CMEs 3
The relationship between the field orientation and the geomagnetic
storm for magnetic cloud is much better than that for ejecta implying
that the field orientation of the magnetic clouds are well conserved
through the heliosphere 4 The CME earthward direction seems to be a
key parameter to select geoeffective CMEs
Title: An Evaluation of the Solar Radio Burst Locator (SRBL) at OVRO
Authors: HwangBo, J. E.; Bong, Su-Chan; Cho, K. S.; Moon, Y. J.; Lee,
D. Y.; Park, Y. D.; Gary, Dale E.; Dougherty, Brian L.
Bibcode: 2005JKAS...38..437H
Altcode:
No abstract at ADS
Title: Examination of type II origin with SOHO/LASCO observations
Authors: Cho, K. -S.; Moon, Y. -J.; Dryer, M.; Shanmugaraju, A.; Fry,
C. D.; Kim, Y. -H.; Bong, S. -C.; Park, Y. -D.
Bibcode: 2005JGRA..11012101C
Altcode:
We examine a possibility that metric type II solar radio bursts are
all caused by coronal mass ejection (CME) generated shocks. For this
we consider 129 type II flare events from February 1997 to October
2000 and examine their associations with SOHO/LASCO CMEs according to
their temporal and spatial closeness using SOHO/EIT and GOES data. We
then carefully inspected 26 CME-less events to examine if there are
CME-related features in LASCO and EIT images. In addition we examined
28 limb type II CME events to compare the kinematics of coronal shocks
with those of the CME fronts. Under the assumption that the observed
type IIs are all generated by CME-related shocks, we determine the
formation heights of the CME-associated type IIs using LASCO CME
speeds and type II onset times. From these studies, we have found
(1) a large fraction (81%) of the type II bursts have temporal and
spatial association with CMEs, and the association increases as their
source position approaches to the limb; (2) most of the events without
the association are related with weak flares and/or disk events;
(3) most of the events are super-Alfvenic with a mean speed of 900
km s-1; (4) the front heights of all CMEs except for a few
events are in the range of 1 to 3 solar radii, which are consistent with
the type II formation heights; (4) the onset time difference (CME-type
II) of all events are within about ±1 hour, mostly -30 min to 10 min;
(5) the CME speeds have a possible correlation (r = 0.6) with coronal
shock speeds, when two outliers are excluded. Considering a possibility
that some outliers could result from some effects such as the coronal
shock generation at CME flanks and CME accelerations, our results show
that most of the type II bursts can be explained by the CME origin.
Title: Near Real-Time Estimation of Geomagnetic Local K Index From
Gyeongzu Magnetometer
Authors: Choi, K. -C.; Cho, K. -S.; Moon, Y. -J.; Kim, K. -H.; Lee,
D. -Y.; Park, Y. -D.; Lim, M. -T.; Lim, H. -R.; Park, Y. -S.
Bibcode: 2005JASS...22..431C
Altcode:
Local K-index is an indicator representing local geomagnetic activity
in every 3 hour. For estimation of the local K-index, a reasonable
determination of solar quiet curve (undisturbed daily variation
of geomagnetic field) is quiet essential. To derive the solar quiet
curve, the FMI method, which is one of representative algorithms, uses
horizontal components (H and D) of 3 days magnetometer data from the
previous day to the next day for a specific day. However, this method
is not applicable to real time forecast since it always requires the
next day data. In this study, we have devised a new method to estimate
local K-index in near real-time by modifying the FMI method. The new
method selects a recent quiet day whose Kp indices, reported by NOAA/SEC
are all lower than 3, and replace the previous day and the next day
data by the recent quiet day data. We estimated 2,672 local K indices
from Gyeongzu magnetometer in 2003, and then compared the indices with
those from the conventional FMI method. We also compared the K indices
with those from Kakioka observatory. As a result, we found that (1)
K indices from the new method are nearly consistent with those of
the conventional FMI method with a very high correlation (R = 0.96);
(2) our local K indices also have a relatively high correlation (R =
0.81) with those from Kakioka station. Our results show that the new
method can be used for near real-time estimation of local K indices
from Gyeongzu magnetometer.
Title: A Study of Flare-associated X-Ray Plasma
Ejections. III. Kinematic Properties
Authors: Kim, Yeon-Han; Moon, Y. -J.; Cho, K. -S.; Bong, Su-Chan;
Park, Y. D.
Bibcode: 2005ApJ...635.1291K
Altcode:
In this study, we have investigated the kinematic properties of
flare-associated X-ray plasma ejections. First, we obtained the
speed profiles of well-observed several events and compared them
with the GOES soft X-ray flux profiles as well as the HXT hard X-ray
flux profiles of their associated flares. Second, we have estimated
the Alfvén speed at the observing height of X-ray plasma ejections
in order to find whether the X-ray plasma ejection is a reconnection
outflow as predicted by standard magnetic reconnection model. Finally,
we have estimated the representative speeds of all 137 X-ray plasma
ejections and then compared them with the speeds of the coronal mass
ejections (CMEs). Our main results are as follows: (1) X-ray plasma
ejections usually initially accelerate and then constantly propagate or
slowly decelerate; (2) for several well-observed examples, the speed
profiles of X-ray plasma ejections are similar to those of the hard
X-ray emission profiles; (3) the speed of an X-ray plasma ejection
ranges from 30 to 1300 km s-1, with a mean speed of 230
km s-1, and the speed of a CME ranges from 150 to 2000 km
s-1 with a mean value of 530 km s -1 (4) there is
no statistical correlation between the speeds of X-ray plasma ejections
and the corresponding CME speeds; (5) an X-ray plasma ejection seems
to have a much shorter acceleration duration (less than 10 minutes)
than that of a CME (larger than 30 minutes). On the basis of these
results, we suggest that the majority of X-ray plasma ejections are
not likely to be the X-ray counterpart of CMEs but outflows generated
by magnetic reconnection, at least from the kinematical point of view.
Title: Observational Study of Solar X-ray Plasma Ejections
Authors: Kim, Y.; Moon, Y.; Cho, K.; Park, Y.
Bibcode: 2005AGUFMSH12A..01K
Altcode:
X-ray plasma ejections (XPEs) often occurred around the impulsive
phase of solar flares and have been well observed by the SXT aboard
Yohkoh. In this study we have carried out observational studies of XPEs
in order to address the identification of the XPE. Firstly, we have made
a comprehensive statistical study of the relationship between XPEs and
coronal mass ejections (CMEs). For this we considered 279 limb flares
from all flare mode data in Yohkoh SXT observation during the last solar
maximum (1999-2001). For these flares, we examined associated XPEs and
CMEs to make clear the relationship between XPEs and CMEs temporally
and spatially. Secondly, we have classified 137 XPEs into five groups
according to their shape, such as loop-type (60 events), spray-type
(40 events), jet-type (11 events), confined ejection (18 events),
and others (8 events). We also examined the physical properties for
each group. Thirdly, we have investigated the kinematic properties of
the XPEs. For this purpose, we examined the speed profiles of selected
events and estimated the representative speeds of 137 XPEs to compare
with the CME speeds and the estimated Alfven speeds. Main results
of our study are summarized as follows: (1) the XPE usually does not
represent the early signatures of the CME leading edge but are closely
associated with CMEs; (2) the group-dependence of XPE properties, such
as CME association and speed, imply that the physical characteristics
of the XPEs are closely associated with magnetic field configurations
near the reconnection regions; (3) the majority of XPEs are not likely
to be the X-ray counterpart of CMEs but outflows generated by magnetic
reconnection, at least from its kinematical point of view.
Title: A Statistical Analysis of Solar Wind Dynamic Pressure Pulses
During Geomagnetic Storms
Authors: Baek, J. -H.; Lee, D. -Y.; Kim, K. C.; Choi, C. R.; Moon,
Y. -J.; Cho, K. -S.; P., Y. -D.
Bibcode: 2005JASS...22..419B
Altcode:
We have carried out a statistical analysis on solar wind dynamic
pressure pulses during geomagnetic storms. The Dst index was used to
identify 111 geomagnetic storms that occurred in the time interval from
1997 through 2001. We have selected only the events having the minimum
Dst value less than --50 nT. In order to identify the pressure impact
precisely, we have used the horizontal component data of the magnetic
field H (northward) at low latitudes as well as the solar wind pressure
data themselves. Our analysis leads to the following results: (1) The
enhancement of H due to a pressure pulse tends to be proportional to the
magnitude of minimum Dst value; (2) The occurrence frequency of pressure
pulses also increases with storm intensity. (3) For about 30% of our
storms, the occurrence frequency of pressure pulses is greater than
0.4 #/hr, implying that for those storms the pressure pulses occur more
frequently than do periodic substorms with an average substorm duration
of 2.5 hrs. In order to understand the origin of these pressure pulses,
we have first examined responsible storm drivers. It turns out that
65% of the studied storms are driven by coronal mass ejections (CMEs)
while others are associated with corotating interaction regions (6.3%)
or Type II bursts (7.2%). Out of the storms that are driven by CMEs,
over 70% show that the main phase interval overlaps with the sheath,
namely, the region between CME body and the shock, and with the leading
region of a CME. This suggests that the origin of the frequent pressure
pulses is often due to density fluctuations in the sheath region and
the leading edge of the CME body.
Title: Multiple Type II Solar Radio Bursts
Authors: Shanmugaraju, A.; Moon, Y. -J.; Cho, K. -S.; Kim, Y. -H.;
Dryer, M.; Umapathy, S.
Bibcode: 2005SoPh..232...87S
Altcode:
We report on the detailed analysis of a set of 38 multiple type II radio
bursts observed by Culgoora radio spectrograph from January 1997 to July
2003. These events were selected on the basis of the following criteria:
(i) more than one type II were reported within 30 min interval, (ii)
both fundamental and harmonic were identified for each of them. The
X-ray flares and CMEs associated with these events are identified using
GOES, Yohkoh SXT, SOHO/EIT, and SOHO/LASCO data. From the analysis of
these events, the following physical characteristics are obtained: (i)
In many cases, two type IIs with fundamental and harmonic were reported,
and the time interval between the two type IIs is within 15 min; (ii)
The mean values of starting frequency, drift rate, and shock speed of
the first type II are significantly higher than those of the second
type II; (iii) More than 90% of the events are associated with both
X-ray flares and CMEs; (iv) Nearly 75% of the flares are stronger than
M1 X-ray class and 50% of CMEs have their widths larger than 200^∘
or they are halo CMEs; (v) While most of the first type IIs started
within the flare impulsive phase, 22 out of 38 second type IIs started
after the flare impulsive phase. Weak correlations are found between the
starting and ending frequencies of these type II events. On the other
hand, there was no correlation between two shock speeds between the
first and the second type II. Since most of the events are associated
with both the flares and CMEs, and there are no events which are only
associated with multiple impulsive flares or multiple mass ejections,
we suggest that the flares and CMEs (front or flank) both be sources
of multiple type IIs. Other possibilities on the origin of multiple
type IIs are also discussed.
Title: Forecast evaluation of the coronal mass ejection (CME)
geoeffectiveness using halo CMEs from 1997 to 2003
Authors: Kim, R. -S.; Cho, K. -S.; Moon, Y. -J.; Kim, Y. -H.; Yi,
Y.; Dryer, M.; Bong, Su-Chan; Park, Y. -D.
Bibcode: 2005JGRA..11011104K
Altcode:
In this study we have made a forecast evaluation of geoeffective
coronal mass ejections (CMEs) by using frontside halo CMEs and the
magnetospheric ring current index, Dst. This is the first time, to
our knowledge, that an attempt has been made to construct contingency
tables depending on the geoeffectiveness criteria as well as to
estimate the probability of CME geoeffectiveness depending on CME
location and/or speed. For this, we consider 7742 CMEs observed by
SOHO/LASCO and select 305 frontside halo CMEs with their locational
information from 1997 to 2003 using SOHO/EIT images and GOES data. To
select CME-geomagnetic storm (Dst < -50 nT) pairs, we adopt a
CME propagation model for estimating the arrival time of each CME at
the Earth and then choose the nearest Dst minimum value within the
window of ±24 hours. For forecast evaluation, we present contingency
tables to estimate statistical parameters such as probability of
detection yes (PODy) and false alarm ratio (FAR). We examine the
probabilities of CME geoeffectiveness according to their locations,
speeds, and their combination. From these studies, we find that (1)
the total probability of geoeffectiveness for frontside halo CMEs is
40% (121/305); (2) PODys for the location (L < ∣50°∣) and the
speed (>400 km s-1) are estimated to be larger than 80%
but their FARs are about 60%; (3) the most probable areas (or coverage
combinations) whose geoeffectiveness fraction is larger than the mean
probability (∼40%), are 0° < L < +30° for slower speed CMEs
(≤800 km s-1), and -30° < L < +60° for faster
CMEs (>800 km s-1); (4) when the most probable area is
adopted as the new criteria, the PODy becomes slightly lower, but all
other statistical parameters such as FAR and bias are significantly
improved. Our results can give us some criteria to select geoeffective
CMEs with the probability of geoeffectiveness depending on the location,
speed, and their combination.
Title: A new perspective on the role of the solar wind dynamic
pressure in the ring current particle loss through the magnetopause
Authors: Kim, Kyung Chan; Lee, D. -Y.; Lee, E. S.; Choi, C. R.; Kim,
K. H.; Moon, Y. J.; Cho, K. S.; Park, Y. D.; Han, W. Y.
Bibcode: 2005JGRA..110.9223K
Altcode: 2005JGRA..11009223K
It has been known that (untrapped) ring current particles can be
lost through the dayside magnetopause into the magnetosheath, which
is regarded as one of the major mechanisms contributing to the ring
current decay. In this paper, we suggest that the solar wind dynamic
pressure can play a significant role in the dayside loss in a new
aspect. In order to show that, we have first analyzed the average
characteristics of the dynamic pressure based on 95 geomagnetic storm
events selected from the period 1997-2002. We find that the dynamic
pressure overall enhances during the magnetic storm. The enhancement is
most significant during the storm main phase compared to the prestorm
and recovery phases, and it is higher for stronger storms. Using one
of the most recent Tsyganenko models, T01s, we show that this enhanced
dynamic pressure that pushes the magnetopause to move inward leads to
a reduction of the scale length of the gradient of the magnetic field
magnitude along the magnetopause. This results in the enhancement of
the magnetic drift speed across the magnetopause. On the basis of the
test particle orbit calculation, we explicitly show that this effect
can be a significant factor for the particles to effectively cross
the magnetopause. It applies to the adiabatic particles that have a
relatively "small" gyroradius near the magnetopause compared to the
magnetopause thickness. These particles cross the magnetopause by
some number of the magnetic gradient drift motion, being in contrast
to the particles with a relatively "large" gyroradius that can enter
into the magnetosheath by crossing the magnetopause with less than
one gyromotion. We argue that this can often apply to a substantial
population of the ring current particles.
Title: New extrapolation method for coronal mass ejection onset
time estimation
Authors: Moon, Y. -J.; Cho, K. -S.; Chae, Jongchul; Choe, G. S.; Kim,
Y. -H.; Bong, Su-Chan; Park, Y. -D.
Bibcode: 2005JGRA..110.7103M
Altcode: 2005JGRA..11007103M
The onset time of a coronal mass ejection (CME) is usually extrapolated
from its speed in a coronagraph using the constant speed method. In
this study, we present a new empirical method for extrapolating
the onset times of flare-associated CMEs. For this we reexamined
seven well-observed CME-flare events whose initial eruption speeds
are estimated to be about a few tens of kilometers per second from
LASCO C1 coronagraph or loop displacements seen in SOHO/EIT and TRACE
images. In this study, the CME onset time is assumed to be the earliest
observable time of eruption from these images. We estimated the onset
time differences between the CMEs and the associated flares observed
in soft X rays. We then compared them with the onset time differences
estimated by the constant speed extrapolation method from LASCO C2
positions. It is noted that there is a certain quadratic relation
between the CME speed first observed in the LASCO C2 field of view
and the observed CME travel time from near the solar surface to the
C2 field of view in units of the travel time estimated by the constant
speed method. This empirical relation thus enables us to determine the
onset times of CMEs without any assumption in CME kinematics. We have
applied the new empirical method to 91 flare-associated CMEs that were
accompanied by type II bursts. The onset time difference for these
events as well as the well-observed events shows that in most cases
(about 80%) the CME initiation precedes the onset of the associated
flare. This result provides an important clue to the mechanism and
relation of CMEs and flares.
Title: A study of cosmic ray secondaries induced by the Mir space
station using AMS-01
Authors: Aguilar, M.; Alcaraz, J.; Allaby, J.; Alpat, B.; Ambrosi,
G.; Anderhub, H.; Ao, L.; Arefiev, A.; Azzarello, P.; Babucci, E.;
Baldini, L.; Basile, M.; Barancourt, D.; Barao, F.; Barbier, G.;
Barreira, G.; Battiston, R.; Becker, R.; Becker, U.; Bellagamba,
L.; Béné, P.; Berdugo, J.; Berges, P.; Bertucci, B.; Biland, A.;
Bizzaglia, S.; Blasko, S.; Boella, G.; Boschini, M.; Bourquin, M.;
Brocco, L.; Bruni, G.; Buénerd, M.; Burger, J. D.; Burger, W. J.;
Cai, X. D.; Camps, C.; Cannarsa, P.; Capell, M.; Carosi, G.; Casadei,
D.; Casaus, J.; Castellini, G.; Cecchi, C.; Chang, Y. H.; Chen, H. F.;
Chen, H. S.; Chen, Z. G.; Chernoplekov, N. A.; Chiueh, T. H.; Cho, K.;
Choi, M. J.; Choi, Y. Y.; Chuang, Y. L.; Cindolo, F.; Commichau, V.;
Contin, A.; Cortina-Gil, E.; Cristinziani, M.; da Cunha, J. P.; Dai,
T. S.; Delgado, C.; Demirköz, B.; Deus, J. D.; Dinu, N.; Djambazov,
L.; D'Antone, I.; Dong, Z. R.; Emonet, P.; Engelberg, J.; Eppling,
F. J.; Eronen, T.; Esposito, G.; Extermann, P.; Favier, J.; Fiandrini,
E.; Fisher, P. H.; Fluegge, G.; Fouque, N.; Galaktionov, Yu.; Gervasi,
M.; Giusti, P.; Grandi, D.; Grimm, O.; Gu, W. Q.; Hangarter, K.; Hasan,
A.; Henning, R.; Hermel, V.; Hofer, H.; Huang, M. A.; Hungerford,
W.; Ionica, M.; Ionica, R.; Jongmanns, M.; Karlamaa, K.; Karpinski,
W.; Kenney, G.; Kenny, J.; Kim, D. H.; Kim, G. N.; Kim, K. S.; Kim,
M. Y.; Klimentov, A.; Kossakowski, R.; Koutsenko, V.; Kraeber, M.;
Laborie, G.; Laitinen, T.; Lamanna, G.; Lanciotti, E.; Laurenti, G.;
Lebedev, A.; Lechanoine-Leluc, C.; Lee, M. W.; Lee, S. C.; Levi, G.;
Levtchenko, P.; Liu, C. L.; Liu, H. T.; Lopes, I.; Lu, G.; Lu, Y. S.;
Lübelsmeyer, K.; Luckey, D.; Lustermann, W.; Maña, C.; Margotti,
A.; Mayet, F.; McNeil, R. R.; Meillon, B.; Menichelli, M.; Mihul,
A.; Monreal, B.; Mourao, A.; Mujunen, A.; Palmonari, F.; Papi, A.;
Park, H. B.; Park, W. H.; Pauluzzi, M.; Pauss, F.; Perrin, E.; Pesci,
A.; Pevsner, A.; Pimenta, M.; Plyaskin, V.; Pojidaev, V.; Pohl, M.;
Postolache, V.; Produit, N.; Rancoita, P. G.; Rapin, D.; Raupach,
F.; Ren, D.; Ren, Z.; Ribordy, M.; Richeux, J. P.; Riihonen, E.;
Ritakari, J.; Ro, S.; Roeser, U.; Rossin, C.; Sagdeev, R.; Santos,
D.; Sartorelli, G.; Sbarra, C.; Schael, S.; Schultz von Dratzig, A.;
Schwering, G.; Scolieri, G.; Seo, E. S.; Shin, J. W.; Shoumilov, E.;
Shoutko, V.; Siedling, R.; Son, D.; Song, T.; Steuer, M.; Sun, G. S.;
Suter, H.; Tang, X. W.; Ting, Samuel C. C.; Ting, S. M.; Tornikoski,
M.; Torsti, J.; Trümper, J.; Ulbricht, J.; Urpo, S.; Valtonen, E.;
Vandenhirtz, J.; Velcea, F.; Velikhov, E.; Verlaat, B.; Vetlitsky,
I.; Vezzu, F.; Vialle, J. P.; Viertel, G.; Vité, D.; von Gunten,
H.; Waldmeier Wicki, S.; Wallraff, W.; Wang, B. C.; Wang, J. Z.;
Wang, Y. H.; Wiik, K.; Williams, C.; Wu, S. X.; Xia, P. C.; Yan,
J. L.; Yan, L. G.; Yang, C. G.; Yang, J.; Yang, M.; Ye, S. W.; Yeh,
P.; Xu, Z. Z.; Zhang, H. Y.; Zhang, Z. P.; Zhao, D. X.; Zhu, G. Y.;
Zhu, W. Z.; Zhuang, H. L.; Zichichi, A.; Zimmermann, B.; Zuccon, P.
Bibcode: 2005NIMPB.234..321A
Altcode: 2004hep.ex....6065T; 2004hep.ex....6065C
The Alpha Magnetic Spectrometer (AMS-02) is a high energy particle
physics experiment that will study cosmic rays in the ∼100 MeV to
1 TeV range and will be installed on the International Space Station
(ISS) for at least 3 years. A first version of AMS-02, AMS-01, flew
aboard the space shuttle Discovery from June 2 to June 12, 1998,
and collected 108 cosmic ray triggers. Part of the Mir
space station was within the AMS-01 field of view during the four day
Mir docking phase of this flight. We have reconstructed an image of
this part of the Mir space station using secondary π-
and μ- emissions from primary cosmic rays interacting
with Mir. This is the first time this reconstruction was performed in
AMS-01, and it is important for understanding potential backgrounds
during the 3 year AMS-02 mission.
Title: New Geoeffective Parameters of Very Fast Halo Coronal Mass
Authors: Moon, Y.; Cho, K.; Dryer, M.; Kim, Y.; Bong, S.; Chae, J.;
Park, Y.
Bibcode: 2005AGUSMSH23A..01M
Altcode:
We have examined the physical characteristics of very fast coronal
mass ejections (CMEs) and their geoeffective parameters. For this we
consider SOHO/LASCO CMEs whose speeds are larger than 1300 km s-1. By
examining all SOHO/EIT and SOHO/LASCO images of the CMEs, we selected
38 front-side very fast CMEs and then examined their associations with
solar activity such as X-ray flares and Type II bursts. As a result,
we found that among these frontside fast CMEs, 25 are halo (or full
halo) CMEs with span of 360 degrees; 12 are partial halo CMEs with
span greater than 130 degrees; only 1 is broadside CME with span of 53
degrees. There are 13 events that are shock deflected CMEs: 6 are full
halo CMEs and 7 are partial halo CMEs. It is found that about 60 %
(23/38) CMEs were ejected from the western hemisphere. We also note
that these very fast CMEs have very high associations with other solar
activities: all the CMEs are associated with X-ray flares (X-12, M-23,
C-3), and about 80 % of the CMEs (33/38) were accompanied by Type II
bursts. For the examination of CME geoeffectiveness, we select 12 halo
CMEs whose longitudes are less than 40 degrees, which are thought to
be the most plausible candidates of geoeffective CMEs. Then we examine
the relationship between their CME physical parameters (mass, column
density, location of an associated flare, and direction) and the Dst
index. Especially, a CME direction parameter, which is defined as the
maximum ratio of its shorter front from solar disk center and its longer
one, is proposed as a new geoeffective parameter. Its major advantage
is that it can be directly estimated from coronagraph observation. It
is found that while the location of the associated flare has a poor
relationship with the Dst index, the new direction parameter has a
relatively good relationship. In addition, the column density of a CME
also has a comparable good correlation with the Dst index. Noting that
the CME column density is strongly affected by the direction of a CME,
our results imply that the CME direction seems to be the most important
parameter that controls the geoeffectiveness of very fast halo CMEs.
Title: New Geoeffective Parameters of Very Fast Halo Coronal Mass
Ejections
Authors: Moon, Y. -J.; Cho, K. -S.; Dryer, M.; Kim, Y. -H.; Bong,
Su-chan; Chae, Jongchul; Park, Y. D.
Bibcode: 2005ApJ...624..414M
Altcode:
We have examined the physical characteristics of very fast coronal mass
ejections (CMEs) and their geoeffective parameters. For this we consider
SOHO LASCO CMEs whose speeds are larger than 1300 km s-1. By
examining all SOHO EIT and SOHO LASCO images of the CMEs, we selected
38 front-side very fast CMEs and then examined their associations with
solar activity such as X-ray flares and type II bursts. As a result,
we found that among these front-side fast CMEs, 25 are halo (or full
halo) CMEs with span of 360°, 12 are partial halo CMEs with span
greater than 130°, and only one is a broadside CME, with a span of
53°. There are 13 events that are shock-deflected CMEs: six are full
halo CMEs, and seven are partial halo CMEs. It is found that about 60%
(23/38) CMEs were ejected from the western hemisphere. We also note
that these very fast CMEs have very high associations with other solar
activities: all the CMEs are associated with X-ray flares (X-12, M-23,
C-3), and about 80% of the CMEs (33/38) were accompanied by type II
bursts. For the examination of CME geoeffectiveness, we select 12 halo
CMEs whose longitudes are less than 40°, which are thought to be the
most plausible candidates of geoeffective CMEs. Then we examine the
relation between their CME physical parameters (mass, column density,
location of an associated flare, and direction) and the Dst index. In
particular, a CME direction parameter, which is defined as the maximum
ratio of its shorter front from solar disk center and its longer one,
is proposed as a new geoeffective parameter. Its major advantage is
that it can be directly estimated from coronagraph observation. It
is found that while the location of the associated flare has a poor
correlation with the Dst index, the new direction parameter has a
relatively good correlation. In addition, the column density of a CME
also has a comparable good correlation with the Dst index. Noting that
the CME column density is strongly affected by the direction of a CME,
our results imply that the CME direction seems to be the most important
parameter that controls the geoeffectiveness of very fast halo CMEs.
Title: Examination of Type II Origin with SOHO/LASCO Observations
Authors: Cho, K.; Moon, Y.; Dryer, M.; Shanmugaraju, A.; Fry, C.;
Kim, Y.; Park, Y.
Bibcode: 2005AGUSMSP23A..10C
Altcode:
We examine a possibility that the origin of metric-type II solar
radio bursts are coronal mass ejections (CMEs). For this we consider
129 type IIs-flare events from February 1997 to October 2000, and
examine their association with SOHO/LASCO CMEs according to their
time closeness. Among 129 events, we select 27 limb type II-CME events
whose solar surface locations are identified by comparing LASCO and EIT
running difference images. In addition, we examine four CMEs observed by
LASCO C1 or MLSO Mk4 coronagraph at the time of type II bursts. Under
the assumption that the observed type IIs are all generated by CMEs,
we determine the formation heights of the CME-associated type IIs
using LASCO CME seeds and type II onset times. The criteria for shock
formation is assumed that the CME speed is larger than the empirically
determined Alfvén speed, and the shock formation height is located
within the range taking into account the coronal density effect
and the observed type II starting frequencies. From these studies,
we have found: (1) the type II bursts associated with CMEs do not
strongly depend on longitude but more than 80 % events of the limb
events seems to have temporal and spatial association with CMEs; (2)
while 61 % (19/31) CMEs (Class I) satisfy the criteria for coronal
shock formation, 39% (12/31) CMEs (Class II) violate the criteria;
(3) the onset time comparison shows that while the Class I CMEs
occurred just before (or nearly simultaneously) the type II onset,
the onset time differences (CME - type II) of the Class II CMEs are
widely scattered; and (4) the speeds of the Class I CMEs have a much
better correlation with coronal shock speeds estimated from type II
data than those of the Class II CMEs. Our results show that all type
II bursts can not be explained by only CMEs, but large fraction of
type IIs have close association with CMEs.
Title: A Study of Flare-associated X-Ray Plasma
Ejections. I. Association with Coronal Mass Ejections
Authors: Kim, Yeon-Han; Moon, Y. -J.; Cho, K. -S.; Kim, Kap-Sung;
Park, Y. D.
Bibcode: 2005ApJ...622.1240K
Altcode:
We have made a comprehensive statistical study of the relationship
between flare-associated X-ray plasma ejections and coronal mass
ejections (CMEs). For this we considered all flare-mode data in Yohkoh
SXT observations from 1999 April to 2001 March and then selected 279
limb flares seen at longitudes greater than 60°. For these events,
we identified whether there were associated X-ray plasma ejections
or not. We found that about half (137/279) of the flares have X-ray
plasma ejections, and we present a comprehensive list of these with
their event times and speeds. We then determined whether there was an
association between the flares with plasma ejections and CMEs detected
by the Solar and Heliospheric Observatory LASCO instrument, on the
basis of temporal and spatial proximity. It is found that about 69%
(95/137) of the X-ray plasma ejections are associated with CMEs and
that about 84% (119/142) of the events without plasma ejections do
not have related CMEs. The associations are found to increase with
flare strength and duration. We find that X-ray plasma ejections occur
nearly simultaneously with the hard X-ray flare peak, supporting the
idea that the X-ray plasma ejections are tightly associated with the
flaring process. When the CMEs are extrapolated into the Yohkoh field
of view for 43 selected, well-observed events, it is found that about
80% of the CMEs preceded X-ray plasma ejections, by approximately
20 minutes on average. Our results show that X-ray plasma ejections
usually do not represent the early signature of a CME's leading edge
but are closely associated with CMEs.
Title: Study of Flare-Associated X-Ray Plasma Ejections :
II. Morphological Classification
Authors: KIM, YEON-HAN; MOON, Y. -J.; CHO, K. -S.; BONG, SU-CHAN;
PARK, Y. -D.
Bibcode: 2004JKAS...37..171K
Altcode:
No abstract at ADS
Title: Flare-Associated Coronal Mass Ejections with Large
Accelerations
Authors: Moon, Y. -J.; Cho, K. S.; Smith, Z.; Fry, C. D.; Dryer, M.;
Park, Y. D.
Bibcode: 2004ApJ...615.1011M
Altcode:
It is well known that while flare-associated coronal mass ejections
(CMEs) show higher speeds and little acceleration in the corona,
filament-associated CMEs have lower speeds and large accelerations. In
this paper, we examine three flare-associated CMEs with relatively
large accelerations as counterexamples of the former tendency. The
estimated accelerations are all larger than 45 m s-2 below
15 Rsolar. By analyzing SOHO EIT, SOHO LASCO, and GOES
data, we attempt to find out what kind of physical characteristics
control such strong accelerations. The first event is the 1999 July
9 event associated with a C1.1 flare. Considering the fact that
its CME appearance, seen in the LASCO running difference imagery,
is quite similar to the shape of a helmet streamer, we speculate
that its eruption is related to the destabilization of a helmet
streamer, which may induce the weak X-ray flare. The second event
is the 1999 August 17 event associated with a C2.6 flare. The CME
speed abruptly increased from 232 to 909 km s-1 for 1 hr,
and the strong acceleration is coincident with the occurrence of a
subsequent flare/CME. The third event is the 2000 November 24 event
associated with a C4.1 flare. The CME speed first decreased and then
constantly accelerated for 3 hr. The start of such an acceleration is
also coincident with a subsequent CME/flare event. For the last two
CME events, the Lorentz forces acting on the subsequent events may
play an important role in accelerating CMEs. Our results show that
large accelerations of flare-associated CMEs, as counterexamples of
the two classes of CMEs, seem to be caused by other solar activities,
such as helmet streamer disruptions or subsequent CMEs/flares.
Title: A statistical comparison of interplanetary shock and CME
propagation models
Authors: Cho, K. -S.; Moon, Y. -J.; Dryer, M.; Fry, C. D.; Park,
Y. -D.; Kim, K. -S.
Bibcode: 2003JGRA..108.1445C
Altcode:
We have compared the prediction capability of two types of Sun-Earth
connection models: (1) ensemble of physics-based shock propagation
models (STOA, STOA-2, ISPM, and HAFv.2) and (2) empirical CME
propagation (CME-ICME and CME-IP shock) models. For this purpose,
we have selected 38 near-simultaneous pairs of coronal mass ejections
(CMEs) and metric type II radio bursts. By applying the adopted models
to these events, we have estimated the time difference between predicted
and observed arrivals of interplanetary (IP) shocks and ICMEs at the
Earth or L1. The mean absolute error of the shock arrival time (SAT)
within an adopted window of +/-24 hours is 9.8 hours for the ensemble of
shock propagation models, 9.2 hours for the CME-IP shock model, and 11.6
hours for the CME-ICME model. It is also found that the success rate for
all models is about 80% for the same window. The results imply that the
adopted models are comparable in their prediction of the arrival times
of IP shocks and interplanetary CMEs (ICMEs). The usefulness of these
models is also discussed in terms of real-time forecasts, underlying
physics, and identification of IP shocks and ICMEs at the Earth.
Title: Initial Results of the Ichon Solar Radio Spectrograph
Authors: Cho, K. -S.; Kim, K. -S.; Moon, Y. -J.; Dryer, M.
Bibcode: 2003SoPh..212..151C
Altcode:
A new solar radio spectrograph to observe solar radio bursts has been
installed at the Ichon branch of the Radio Research Laboratory, Ministry
of Information and Communication, Korea. The spectrograph consists of
three different antennas to sweep a wide band of frequencies in the
range of 30 MHz ∼ 2500 MHz. Its daily operation is fully automated
and typical examples of solar radio bursts have been successfully
observed. In this paper we describe briefly its hardware and data
processing methods. Then we present coronal shock speeds estimated for
34 type II bursts from May 1998 to November 2000 and compare them with
those from other observatories. We also present the close relationship
between onset time of type II bursts and X-ray flares as well as their
associations with coronal mass ejections.
Title: The Alpha Magnetic Spectrometer (AMS) on the International
Space Station: Part I - results from the test flight on the space
shuttle
Authors: AMS Collaboration; Aguilar, M.; Alcaraz, J.; Allaby, J.;
Alpat, B.; Ambrosi, G.; Anderhub, H.; Ao, L.; Arefiev, A.; Azzarello,
P.; Babucci, E.; Baldini, L.; Basile, M.; Barancourt, D.; Barao,
F.; Barbier, G.; Barreira, G.; Battiston, R.; Becker, R.; Becker,
U.; Bellagamba, L.; Béné, P.; Berdugo, J.; Berges, P.; Bertucci,
B.; Biland, A.; Bizzaglia, S.; Blasko, S.; Boella, G.; Boschini, M.;
Bourquin, M.; Brocco, L.; Bruni, G.; Buénerd, M.; Burger, J. D.;
Burger, W. J.; Cai, X. D.; Camps, C.; Cannarsa, P.; Capell, M.;
Casadei, D.; Casaus, J.; Castellini, G.; Cecchi, C.; Chang, Y. H.;
Chen, H. F.; Chen, H. S.; Chen, Z. G.; Chernoplekov, N. A.; Chiueh,
T. H.; Cho, K.; Choi, M. J.; Choi, Y. Y.; Chuang, Y. L.; Cindolo, F.;
Commichau, V.; Contin, A.; Cortina-Gil, E.; Cristinziani, M.; da Cunha,
J. P.; Dai, T. S.; Delgado, C.; Deus, J. D.; Dinu, N.; Djambazov, L.;
D'Antone, I.; Dong, Z. R.; Emonet, P.; Engelberg, J.; Eppling, F. J.;
Eronen, T.; Esposito, G.; Extermann, P.; Favier, J.; Fiandrini, E.;
Fisher, P. H.; Fluegge, G.; Fouque, N.; Galaktionov, Yu.; Gervasi,
M.; Giusti, P.; Grandi, D.; Grimms, O.; Gu, W. Q.; Hangarter, K.;
Hasan, A.; Hermel, V.; Hofer, H.; Huang, M. A.; Hungerford, W.;
Ionica, M.; Ionica, R.; Jongmanns, M.; Karlamaa, K.; Karpinski,
W.; Kenney, G.; Kenny, J.; Kim, D. H.; Kim, G. N.; Kim, K. S.; Kim,
M. Y.; Klimentov, A.; Kossakowski, R.; Koutsenko, V.; Kraeber, M.;
Laborie, G.; Laitinen, T.; Lamanna, G.; Lanciotti, E.; Laurenti, G.;
Lebedev, A.; Lechanoine-Leluc, C.; Lee, M. W.; Lee, S. C.; Levi, G.;
Levtchenko, P.; Liu, C. L.; Liu, H. T.; Lopes, I.; Lu, G.; Lu, Y. S.;
Lübelsmeyer, K.; Luckey, D.; Lustermann, W.; Maña, C.; Margotti,
A.; Mayet, F.; McNeil, R. R.; Meillon, B.; Menichelli, M.; Mihul, A.;
Mourao, A.; Mujunen, A.; Palmonari, F.; Papi, A.; Park, H. B.; Park,
W. H.; Pauluzzi, M.; Pauss, F.; Perrin, E.; Pesci, A.; Pevsner, A.;
Pimenta, M.; Plyaskin, V.; Pojidaev, V.; Pohl, M.; Postolache, V.;
Produit, N.; Rancoita, P. G.; Rapin, D.; Raupach, F.; Ren, D.; Ren,
Z.; Ribordy, M.; Richeux, J. P.; Riihonen, E.; Ritakari, J.; Ro,
S.; Roeser, U.; Rossin, C.; Sagdeev, R.; Santos, D.; Sartorelli,
G.; Sbarra, C.; Schael, S.; Schultz von Dratzig, A.; Schwering,
G.; Scolieri, G.; Seo, E. S.; Shin, J. W.; Shoutko, V.; Shoumilov,
E.; Siedling, R.; Son, D.; Song, T.; Steuer, M.; Sun, G. S.; Suter,
H.; Tang, X. W.; Ting, Samuel C. C.; Ting, S. M.; Tornikoski, M.;
Torsti, J.; Trümper, J.; Ulbricht, J.; Urpo, S.; Valtonen, E.;
Vandenhirtz, J.; Velcea, F.; Velikhov, E.; Verlaat, B.; Vetlitsky,
I.; Vezzu, F.; Vialle, J. P.; Viertel, G.; Vité, D.; von Gunten,
H.; Wicki, S. Waldmeier; Wallraff, W.; Wang, B. C.; Wang, J. Z.;
Wang, Y. H.; Wiik, K.; Williams, C.; Wu, S. X.; Xia, P. C.; Yan,
J. L.; Yan, L. G.; Yang, C. G.; Yang, J.; Yang, M.; Ye, S. W.; Yeh,
P.; Xu, Z. Z.; Zhang, H. Y.; Zhang, Z. P.; Zhao, D. X.; Zhu, G. Y.;
Zhu, W. Z.; Zhuang, H. L.; Zichichi, A.; Zimmermann, B.; Zuccon, P.
Bibcode: 2002PhR...366..331A
Altcode:
The Alpha Magnetic Spectrometer (AMS) was flown on the space shuttle
Discovery during flight STS-91 (June 1998) in a 51.7° orbit at
altitudes between 320 and 390km. A search for antihelium nuclei
in the rigidity range 1-140GV was performed. No antihelium nuclei
were detected at any rigidity. An upper limit on the flux ratio of
antihelium to helium of <1.1×10-6 was obtained. The high energy proton, electron, positron, helium, antiproton and
deuterium spectra were accurately measured. For each particle and
nuclei two distinct spectra were observed: a higher energy spectrum and
a substantial second spectrum. Positrons in the second spectrum were
found to be much more abundant than electrons. Tracing particles from
the second spectra shows that most of them travel for an extended period
of time in the geomagnetic field, and that the positive particles (p
and e+) and negative ones (e-) originate from
two complementary geographic regions. The second helium spectrum
flux over the energy range 0.1-1.2GeV/nucleon was measured to be
(6.3+/-0.9)×10-3(m2ssr)-1. Over 90
percent of the helium flux was determined to be 3He at the
90% confidence level.
Title: A revised shock time of arrival (STOA) model for interplanetary
shock propagation: STOA-2
Authors: Moon, Y. -J.; Dryer, M.; Smith, Z.; Park, Y. D.; Cho, K. S.
Bibcode: 2002GeoRL..29.1390M
Altcode: 2002GeoRL..29j..28M
We have examined a possibility for improvement of the STOA (Shock Time
Of Arrival) model for interplanetary shock propagation. In the STOA
model, the shock propagating velocity is given by Vs
~ R-N with N = 0.5, where R is the heliocentric
distance. Noting observational and numerical findings that the radial
dependence of shock wave velocity depends on initial shock wave
velocity, we suggest a simple modified STOA model (STOA-2) which has
a linear relationship between initial coronal shock wave velocity
(Vis) and its deceleration exponent(N), N = 0.05 + 4 ×
10-4Vis, where Vis is a numeric value
expressed in units of km s-1. Our results show that the
STOA-2 model not only removes a systematic dependence of the transit
time difference predicted by the previous STOA model on initial shock
velocity, but also reduces the number of events with large transit
time differences.
Title: Prediction of shock arrival time at the Earth by the STOA-2
model
Authors: Moon, Y.; Dryer, M.; Smith, Z.; Park, Y.; Cho, K.
Bibcode: 2002cosp...34E.472M
Altcode: 2002cosp.meetE.472M
We have examined a possibility for improvement of the STOA (Shock Time
Of Arrival) model for interplanetary shock propagation. In the STOA
model, the shock propagating velocity is given by VsR-N with N=0.5,
where R is the heliocentric distance. Noting observational and numerical
findings that the radial dependence of shock wave velocity depends on
initial shock wave velocity, we suggest a simple modified STOA model
(STOA-2) which has a linear relationship between initial coronal shock
wave velocity (Vis ) and its deceleration exponent(N), N = 0.05 +
4 × 10-4 Vis , where Vis is a numeric value expressed in units of
km s-1 . Our results show that the STOA-2 model not only removes a
systematic dependence of the transit time difference predicted by the
previous STOA model on initial shock velocity, but also reduces the
number of events with large transit time differences.
Title: Study of Predictability of STOA Model For Magnetic Storms
Using Data From Ichon Solar Radio Observatory
Authors: Cho, K.; Lee, D.; Moon, Y.; Kim, K.; Min, K.
Bibcode: 2001AGUFMSH31A0693C
Altcode:
The shock wave launched from the solar coronal activity is crucial and
closely related to the geomagnetic storm occurrence. The propagation
speed of the shock can be determined based on the drift rate of Type II
solar radio burst and a model atmosphere of the corona. These values are
used as inputs in the STOA model (Shock Time of Arrival; Smith et al.,
2000) which can provide predictions on geomagnetic storm occurrence. In
this work, we have attempted to improve such predictability of the STOA
model using the data from Solar Radio Observatory at Ichon, Korea. In
order to estimate the possible errors in the input velocity values of
the coronal shock, we have also used the similar data sets from other
observatories including Culgoora, Hiraiso, and RSTN sites. Also, We
have estimated the dependence of the shock speed on the distance from
the Sun. Further, it was also checked if the IMF structure near the
earth can seriously affect the shock arrival and triggering of the
storm. Finally, the errors between the STOA model prediction and the
actual storm occurrence determined from the Dst index were estimated.
Title: A Statistical Study of Magnetic Strom Recovery Phase:
Preliminary Results
Authors: Lee, D. -Y.; Hwang, J. A.; Min, K. W.; Lee, E. S.; Cho,
K. S.; Kim, S. G.; Bae, S. H.
Bibcode: 2001JASS...18...27L
Altcode:
A statistical study has been performed of the magnetic storm recovery
phase using the Dst index for 102 storm events in the interval January
1996 to December 1998. In 43 cases (or 42%) out of our 102 events, the
recovery phase exhibits fast recovery (taking about 8 hours or less)
at its initial stage or for the entire recovery period. Since this
fast recovery can be explained by the fast charge exchange loss of
O+ ions which mostly come from the ionosphere, and since a
fraction of H+ ions is of ionospheric origin as well, our
statistical result supports the view that the source of ring current
ions in many magnetic storms can be terrestrial.
Title: Ichon Solar Radio Spectrogaphic System and Development of
its Operation Software
Authors: Cho, K. S.; Lee, G. H.; Kim, K. -S.
Bibcode: 1997JASS...14..320C
Altcode:
A solar radio spectrograph for monitoring solar radio emission was
installed at Ichon branch of Radio Research Laboratory in 1995. The
spectrograph consists of three different antennas to sweep a wide
band of frequencies in the range of 30MHz-2500MHz. We have developed
the operating software for the acquisition and the analysis of solar
radio data obtained by solar radio spectrograph in order to carry out
active solar radio observational studies. It was found that by using
our software, we could have very good solar radio data for a sequence
of three TYPE III bursts observed on 4 Nov. 1997. In this paper, we
show the radio spectrograph and the result of the observation by its
operating software.
Title: Role of tephra layers on satellite images in Meteorite Ice
Field near Yamato Mountains, Antarctica.
Authors: Nishio, F.; Cho, K.; Seko, K.; Fukuoka, T.
Bibcode: 1992anme...17....1N
Altcode:
No abstract at ADS