Author name code: lawrence
ADS astronomy entries on 2022-09-14
author:"Lawrence, John K."
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Title: Model-based cross-correlation search for gravitational waves
from the low-mass X-ray binary Scorpius X-1 in LIGO O3 data
Authors: The LIGO Scientific Collaboration; the Virgo Collaboration;
the KAGRA Collaboration; Abbott, R.; Abe, H.; Acernese, F.; Ackley,
K.; Adhicary, S.; Adhikari, N.; Adhikari, R. X.; Adkins, V. K.;
Adya, V. B.; Affeldt, C.; Agarwal, D.; Agathos, M.; Aguiar, O. D.;
Aiello, L.; Ain, A.; Ajith, P.; Akutsu, T.; Albanesi, S.; Alfaidi,
R. A.; Alléné, C.; Allocca, A.; Altin, P. A.; Amato, A.; Anand, S.;
Ananyeva, A.; Anderson, S. B.; Anderson, W. G.; Ando, M.; Andrade, T.;
Andres, N.; Andrés-Carcasona, M.; Andrić, T.; Ansoldi, S.; Antelis,
J. M.; Antier, S.; Apostolatos, T.; Appavuravther, E. Z.; Appert,
S.; Apple, S. K.; Arai, K.; Araya, A.; Araya, M. C.; Areeda, J. S.;
Arène, M.; Aritomi, N.; Arnaud, N.; Arogeti, M.; Aronson, S. M.;
Asada, H.; Ashton, G.; Aso, Y.; Assiduo, M.; Assis de Souza Melo,
S.; Aston, S. M.; Astone, P.; Aubin, F.; AultONeal, K.; Babak, S.;
Badaracco, F.; Badger, C.; Bae, S.; Bae, Y.; Bagnasco, S.; Bai, Y.;
Baier, J. G.; Baird, J.; Bajpai, R.; Baka, T.; Ball, M.; Ballardin,
G.; Ballmer, S. W.; Baltus, G.; Banagiri, S.; Banerjee, B.; Bankar,
D.; Barayoga, J. C.; Barish, B. C.; Barker, D.; Barneo, P.; Barone,
F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett,
J.; Barton, M. A.; Bartos, I.; Basak, S.; Bassiri, R.; Basti, A.;
Bawaj, M.; Bayley, J. C.; Bazzan, M.; Bécsy, B.; Bedakihale, V. M.;
Beirnaert, F.; Bejger, M.; Belahcene, I.; Bell, A. S.; Benedetto,
V.; Beniwal, D.; Benoit, W.; Bentley, J. D.; BenYaala, M.; Bera,
S.; Berbel, M.; Bergamin, F.; Berger, B. K.; Bernuzzi, S.; Beroiz,
M.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.;
Beveridge, D.; Bhandare, R.; Bhandari, A. V.; Bhardwaj, U.; Bhatt,
R.; Bhattacharjee, D.; Bhaumik, S.; Bianchi, A.; Bilenko, I. A.;
Bilicki, M.; Billingsley, G.; Bini, S.; Birnholtz, O.; Biscans,
S.; Bischi, M.; Biscoveanu, S.; Bisht, A.; Biswas, B.; Bitossi,
M.; Bizouard, M. -A.; Blackburn, J. K.; Blair, C. D.; Blair, D. G.;
Blair, R. M.; Bobba, F.; Bode, N.; Boër, M.; Bogaert, G.; Boldrini,
M.; Bolingbroke, G. N.; Bonavena, L. D.; Bondarescu, R.; Bondu, F.;
Bonilla, E.; Bonnand, R.; Booker, P.; Bork, R.; Boschi, V.; Bose,
N.; Bose, S.; Bossilkov, V.; Boudart, V.; Bouffanais, Y.; Bozzi, A.;
Bradaschia, C.; Brady, P. R.; Bramley, A.; Branch, A.; Branchesi,
M.; Brau, J. E.; Breschi, M.; Briant, T.; Briggs, J. H.; Brillet, A.;
Brinkmann, M.; Brockill, P.; Brooks, A. F.; Brooks, J.; Brown, D. D.;
Brunett, S.; Bruno, G.; Bruntz, R.; Bryant, J.; Bucci, F.; Buchanan,
J.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Burtnyk, K.; Buscicchio,
R.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabourn Davies, G. S.;
Cabras, G.; Cabrita, R.; Cadonati, L.; Cagnoli, G.; Cahillane, C.;
Calderón Bustillo, J.; Callaghan, J. D.; Callister, T. A.; Calloni,
E.; Camp, J. B.; Canepa, M.; Caneva, G.; Cannavacciuolo, M.; Cannon,
K. C.; Cao, H.; Cao, Z.; Capistran, L. A.; Capocasa, E.; Capote,
E.; Carapella, G.; Carbognani, F.; Carlassara, M.; Carlin, J. B.;
Carpinelli, M.; Carrillo, G.; Carter, J. J.; Carullo, G.; Casanueva
Diaz, J.; Casentini, C.; Castaldi, G.; Caudill, S.; Cavaglià, M.;
Cavalier, F.; Cavalieri, R.; Cella, G.; Cerdá-Durán, P.; Cesarini,
E.; Chaibi, W.; Chakalis, W.; Chalathadka Subrahmanya, S.; Champion,
E.; Chan, C. -H.; Chan, C.; Chan, C. L.; Chan, K.; Chan, M.; Chandra,
K.; Chang, I. P.; Chang, W.; Chanial, P.; Chao, S.; Chapman-Bird,
C.; Charlton, P.; Chassande-Mottin, E.; Chatterjee, C.; Chatterjee,
Debarati; Chatterjee, Deep; Chaturvedi, M.; Chaty, S.; Chen, C.; Chen,
D.; Chen, H. Y.; Chen, J.; Chen, K.; Chen, X.; Chen, Y. -B.; Chen,
Y. -R.; Chen, Y.; Cheng, H.; Chessa, P.; Cheung, H. Y.; Chia, H. Y.;
Chiadini, F.; Chiang, C-Y.; Chiarini, G.; Chierici, R.; Chincarini,
A.; Chiofalo, M. L.; Chiummo, A.; Choudhary, R. K.; Choudhary, S.;
Christensen, N.; Chu, Q.; Chu, Y-K.; Chua, S. S. Y.; Chung, K. W.;
Ciani, G.; Ciecielag, P.; Cieślar, M.; Cifaldi, M.; Ciobanu, A. A.;
Ciolfi, R.; Clara, F.; Clark, J. A.; Clarke, T. A.; Clearwater, P.;
Clesse, S.; Cleva, F.; Coccia, E.; Codazzo, E.; Cohadon, P. -F.;
Cohen, D. E.; Colleoni, M.; Collette, C. G.; Colombo, A.; Colpi,
M.; Compton, C. M.; Conti, L.; Cooper, S. J.; Corban, P.; Corbitt,
T. R.; Cordero-Carrión, I.; Corezzi, S.; Cornish, N. J.; Corsi, A.;
Cortese, S.; Coschizza, A. C.; Cotesta, R.; Cottingham, R.; Coughlin,
M. W.; Coulon, J. -P.; Countryman, S. T.; Cousins, B.; Couvares, P.;
Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.;
Creighton, J. D. E.; Creighton, T. D.; Criswell, A. W.; Croquette, M.;
Crowder, S. G.; Cudell, J. R.; Cullen, T. J.; Cumming, A.; Cummings,
R.; Cuoco, E.; Curyło, M.; Dabadie, P.; Dal Canton, T.; Dall'Osso,
S.; Dálya, G.; Dana, A.; D'Angelo, B.; Danilishin, S.; D'Antonio, S.;
Danzmann, K.; Darsow-Fromm, C.; Dasgupta, A.; Datrier, L. E. H.; Datta,
Sayak; Datta, Sayantani; Dattilo, V.; Dave, I.; Davier, M.; Davis,
D.; Davis, M. C.; Daw, E. J.; Dax, M.; DeBra, D.; Deenadayalan, M.;
Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Favero, V.; De
Lillo, F.; De Lillo, N.; Dell'Aquila, D.; Del Pozzo, W.; De Matteis,
F.; D'Emilio, V.; Demos, N.; Dent, T.; Depasse, A.; De Pietri, R.;
De Rosa, R.; De Rossi, C.; DeSalvo, R.; De Simone, R.; Dhurandhar,
S.; Diab, R.; Díaz, M. C.; Didio, N. A.; Dietrich, T.; Di Fiore, L.;
Di Fronzo, C.; Di Giorgio, C.; Di Giovanni, F.; Di Giovanni, M.; Di
Girolamo, T.; Diksha, D.; Di Lieto, A.; Di Michele, A.; Di Pace, S.;
Di Palma, I.; Di Renzo, F.; Divakarla, A. K.; Dmitriev, A.; Doctor,
Z.; Doleva, P. P.; Donahue, L.; D'Onofrio, L.; Donovan, F.; Dooley,
K. L.; Dooney, T.; Doravari, S.; Dorosh, O.; Drago, M.; Driggers,
J. C.; Drori, Y.; Ducoin, J. -G.; Dunn, L.; Dupletsa, U.; Durante,
O.; D'Urso, D.; Duverne, P. -A.; Dwyer, S. E.; Eassa, C.; Easter,
P. J.; Ebersold, M.; Eckhardt, T.; Eddolls, G.; Edelman, B.; Edo,
T. B.; Edy, O.; Effler, A.; Eguchi, S.; Eichholz, J.; Eikenberry,
S. S.; Eisenmann, M.; Eisenstein, R. A.; Ejlli, A.; Engelby, E.;
Enomoto, Y.; Errico, L.; Essick, R. C.; Estellés, H.; Estevez, D.;
Etzel, T.; Evans, M.; Evans, T. M.; Evstafyeva, T.; Ewing, B. E.;
Fabrizi, F.; Faedi, F.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan,
P. C.; Farah, A. M.; Farr, B.; Farr, W. M.; Favaro, G.; Favata, M.;
Fays, M.; Fazio, M.; Feicht, J.; Fejer, M. M.; Fenyvesi, E.; Ferguson,
D. L.; Fernandez-Galiana, A.; Ferrante, I.; Ferreira, T. A.; Fidecaro,
F.; Figura, P.; Fiori, A.; Fiori, I.; Fishbach, M.; Fisher, R. P.;
Fittipaldi, R.; Fiumara, V.; Flaminio, R.; Floden, E.; Fong, H. K.;
Font, J. A.; Fornal, B.; Forsyth, P. W. F.; Franke, A.; Frasca, S.;
Frasconi, F.; Freed, J. P.; Frei, Z.; Freise, A.; Freitas, O.; Frey,
R.; Fritschel, P.; Frolov, V. V.; Fronzé, G. G.; Fujii, Y.; Fujikawa,
Y.; Fujimoto, Y.; Fulda, P.; Fyffe, M.; Gabbard, H. A.; Gabella,
W. E.; Gadre, B. U.; Gair, J. R.; Gais, J.; Galaudage, S.; Gamba, R.;
Ganapathy, D.; Ganguly, A.; Gao, D. -F.; Gao, D.; Gaonkar, S. G.;
Garaventa, B.; García-Núñez, C.; García-Quirós, C.; Gardner,
K. A.; Gargiulo, J.; Garufi, F.; Gasbarra, C.; Gateley, B.; Gayathri,
V.; Ge, G. -G.; Gemme, G.; Gennai, A.; George, J.; Gerberding, O.;
Gergely, L.; Ghonge, S.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh,
Shaon; Ghosh, Shrobana; Ghosh, Tathagata; Giacoppo, L.; Giaime,
J. A.; Giardina, K. D.; Gibson, D. R.; Gier, C.; Giri, P.; Gissi,
F.; Gkaitatzis, S.; Glanzer, J.; Gleckl, A. E.; Godoy, F. G.; Godwin,
P.; Goetz, E.; Goetz, R.; Golomb, J.; Goncharov, B.; González, G.;
Gosselin, M.; Gouaty, R.; Gould, D. W.; Goyal, S.; Grace, B.; Grado,
A.; Graham, V.; Granata, M.; Granata, V.; Gras, S.; Grassia, P.; Gray,
C.; Gray, R.; Greco, G.; Green, A. C.; Green, R.; Gretarsson, A. M.;
Gretarsson, E. M.; Griffith, D.; Griffiths, W. L.; Griggs, H. L.;
Grignani, G.; Grimaldi, A.; Grimm, S. J.; Grote, H.; Grunewald, S.;
Gruson, A. S.; Guerra, D.; Guidi, G. M.; Guimaraes, A. R.; Gulati,
H. K.; Gulminelli, F.; Gunny, A. M.; Guo, H. -K.; Guo, Y.; Gupta,
Anchal; Gupta, Anuradha; Gupta, P.; Gupta, S. K.; Gurs, J.; Gustafson,
R.; Gutierrez, N.; Guzman, F.; Ha, S.; Hadiputrawan, I. P. W.; Haegel,
L.; Haino, S.; Halim, O.; Hall, E. D.; Hamilton, E. Z.; Hammond,
G.; Han, W. -B.; Haney, M.; Hanks, J.; Hanna, C.; Hannam, M. D.;
Hannuksela, O.; Hansen, H.; Hanson, J.; Harada, R.; Harder, T.; Haris,
K.; Harms, J.; Harry, G. M.; Harry, I. W.; Hartwig, D.; Hasegawa, K.;
Haskell, B.; Haster, C. -J.; Hathaway, J. S.; Hattori, K.; Haughian,
K.; Hayakawa, H.; Hayama, K.; Hayes, F. J.; Healy, J.; Heidmann, A.;
Heidt, A.; Heintze, M. C.; Heinze, J.; Heinzel, J.; Heitmann, H.;
Hellman, F.; Hello, P.; Helmling-Cornell, A. F.; Hemming, G.; Hendry,
M.; Heng, I. S.; Hennes, E.; Hennig, J. -S.; Hennig, M.; Henshaw, C.;
Hernandez, A. G.; Hernandez Vivanco, F.; Heurs, M.; Hewitt, A. L.;
Higginbotham, S.; Hild, S.; Hill, P.; Himemoto, Y.; Hines, A. S.;
Hirata, N.; Hirose, C.; Ho, T-C.; Hochheim, S.; Hofman, D.; Hohmann,
J. N.; Holcomb, D. G.; Holland, N. A.; Hollows, I. J.; Holmes, Z. J.;
Holt, K.; Holz, D. E.; Hong, Q.; Hough, J.; Hourihane, S.; Howell,
D.; Howell, E. J.; Hoy, C. G.; Hoyland, D.; Hreibi, A.; Hsieh, B-H.;
Hsieh, H-F.; Hsiung, C.; Huang, H-Y.; Huang, P.; Huang, Y-C.; Huang,
Y. -J.; Huang, Y.; Hübner, M. T.; Huddart, A. D.; Hughey, B.; Hui,
D. C. Y.; Hui, V.; Husa, S.; Huttner, S. H.; Huxford, R.; Huynh-Dinh,
T.; Hyland, J.; Iandolo, G. A.; Ide, S.; Idzkowski, B.; Iess, A.;
Inayoshi, K.; Inoue, Y.; Iosif, P.; Irwin, J.; Gupta, Ish; Isi,
M.; Ito, K.; Itoh, Y.; Iyer, B. R.; JaberianHamedan, V.; Jacqmin,
T.; Jacquet, P. -E.; Jadhav, S. J.; Jadhav, S. P.; Jain, T.; James,
A. L.; Jan, A. Z.; Jani, K.; Janquart, J.; Janssens, K.; Janthalur,
N. N.; Jaranowski, P.; Jariwala, D.; Jarov, S.; Jaume, R.; Jenkins,
A. C.; Jenner, K.; Jeon, C.; Jia, W.; Jiang, J.; Jin, H. -B.; Johns,
G. R.; Johnston, R.; Johny, N.; Jones, A. W.; Jones, D. I.; Jones,
P.; Jones, R.; Joshi, P.; Ju, L.; Jung, K.; Jung, P.; Junker, J.;
Juste, V.; Kaihotsu, K.; Kajita, T.; Kakizaki, M.; Kalaghatgi, C.;
Kalogera, V.; Kamai, B.; Kamiizumi, M.; Kanda, N.; Kandhasamy, S.;
Kang, G.; Kanner, J. B.; Kao, Y.; Kapadia, S. J.; Kapasi, D. P.;
Karat, S.; Karathanasis, C.; Karki, S.; Kashyap, R.; Kasprzack, M.;
Kastaun, W.; Kato, T.; Katsanevas, S.; Katsavounidis, E.; Katzman,
W.; Kaur, T.; Kawabe, K.; Kawaguchi, K.; Kéfélian, F.; Keitel,
D.; Key, J. S.; Khadka, S.; Khalili, F. Y.; Khan, S.; Khanam, T.;
Khazanov, E. A.; Khetan, N.; Khursheed, M.; Kijbunchoo, N.; Kim,
C.; Kim, J. C.; Kim, J.; Kim, K.; Kim, P.; Kim, W. S.; Kim, Y. -M.;
Kimball, C.; Kimura, N.; King, B.; Kinley-Hanlon, M.; Kirchhoff, R.;
Kissel, J. S.; Klimenko, S.; Klinger, T.; Knee, A. M.; Knust, N.;
Kobayashi, Y.; Koch, P.; Koehlenbeck, S. M.; Koekoek, G.; Kohri, K.;
Kokeyama, K.; Koley, S.; Kolitsidou, P.; Kolstein, M.; Kondrashov,
V.; Kong, A. K. H.; Kontos, A.; Korobko, M.; Kossak, R. V.; Kovalam,
M.; Koyama, N.; Kozak, D. B.; Kozakai, C.; Kranzhoff, L.; Kringel, V.;
Krishnendu, N. V.; Królak, A.; Kuehn, G.; Kuijer, P.; Kulkarni, S.;
Kumar, A.; Kumar, Praveen; Kumar, Prayush; Kumar, Rahul; Kumar, Rakesh;
Kume, J.; Kuns, K.; Kuromiya, Y.; Kuroyanagi, S.; Kuwahara, S.; Kwak,
K.; Lacaille, G.; Lagabbe, P.; Laghi, D.; Lalande, E.; Lalleman, M.;
Lamberts, A.; Landry, M.; Lane, B. B.; Lang, R. N.; Lange, J.; Lantz,
B.; La Rosa, I.; Lartaux-Vollard, A.; Lasky, P. D.; Lawrence, J.;
Laxen, M.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; LeBohec,
S.; Lecoeuche, Y. K.; Lee, E.; Lee, H. M.; Lee, H. W.; Lee, K.; Lee,
R.; Legred, I. N.; Lehmann, J.; Lemaître, A.; Lenti, M.; Leonardi,
M.; Leonova, E.; Leroy, N.; Letendre, N.; Levesque, C.; Levin, Y.;
Leviton, J. N.; Leyde, K.; Li, A. K. Y.; Li, B.; Li, K. L.; Li, P.; Li,
T. G. F.; Li, X.; Lin, C-Y.; Lin, E. T.; Lin, F-K.; Lin, F-L.; Lin,
H. L.; Lin, L. C. -C.; Linde, F.; Linker, S. D.; Littenberg, T. B.;
Liu, G. C.; Liu, J.; Liu, X.; Llamas, F.; Lo, R. K. L.; Lo, T.;
London, L. T.; Longo, A.; Lopez, D.; Lopez Portilla, M.; Lorenzini,
M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lott, T. P.; Lough, J. D.;
Lousto, C. O.; Lovelace, G.; Lowry, M. J.; Lucaccioni, J. F.; Lück,
H.; Lumaca, D.; Lundgren, A. P.; Lung, Y.; Luo, L. -W.; Lussier,
A. W.; Lynam, J. E.; Ma'arif, M.; Macas, R.; MacInnis, M.; Macleod,
D. M.; MacMillan, I. A. O.; Macquet, A.; Magaña Hernandez, I.;
Magazzù, C.; Magee, R. M.; Maggiore, R.; Magnozzi, M.; Mahesh, S.;
Majorana, E.; Makarem, C. N.; Maksimovic, I.; Maliakal, S.; Malik,
A.; Man, N.; Mandic, V.; Mangano, V.; Mannix, B. R.; Mansell, G. L.;
Mansingh, G.; Manske, M.; Mantovani, M.; Mapelli, M.; Marchesoni,
F.; Marín Pina, D.; Marion, F.; Mark, Z.; Márka, S.; Márka, Z.;
Markakis, C.; Markosyan, A. S.; Markowitz, A.; Maros, E.; Marquina,
A.; Marsat, S.; Martelli, F.; Martin, I. W.; Martin, R. M.; Martinez,
M.; Martinez, V. A.; Martinez, V.; Martinovic, K.; Martynov, D. V.;
Marx, E. J.; Masalehdan, H.; Mason, K.; Masserot, A.; Masso-Reid,
M.; Mastrogiovanni, S.; Matas, A.; Mateu-Lucena, M.; Matiushechkina,
M.; Mavalvala, N.; McCann, J. J.; McCarthy, R.; McClelland, D. E.;
McClincy, P. K.; McCormick, S.; McCuller, L.; McGhee, G. I.; McGinn,
J.; McGuire, S. C.; McIsaac, C.; McIver, J.; McLeod, A.; McRae, T.;
McWilliams, S. T.; Meacher, D.; Mehmet, M.; Mehta, A. K.; Meijer,
Q.; Melatos, A.; Mendell, G.; Menendez-Vazquez, A.; Menoni, C. S.;
Mercer, R. A.; Mereni, L.; Merfeld, K.; Merilh, E. L.; Merritt,
J. D.; Merzougui, M.; Messenger, C.; Messick, C.; Meyers, P. M.;
Meylahn, F.; Mhaske, A.; Miani, A.; Miao, H.; Michaloliakos, I.;
Michel, C.; Michimura, Y.; Middleton, H.; Mihaylov, D. P.; Miller,
A.; Miller, A. L.; Miller, B.; Millhouse, M.; Mills, J. C.; Milotti,
E.; Minenkov, Y.; Mio, N.; Mir, Ll. M.; Miravet-Tenés, M.; Mishkin,
A.; Mishra, C.; Mishra, T.; Mistry, T.; Mitchell, A. L.; Mitra, S.;
Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Miyakawa, O.;
Miyo, K.; Miyoki, S.; Mo, Geoffrey; Modafferi, L. M.; Moguel, E.;
Mogushi, K.; Mohapatra, S. R. P.; Mohite, S. R.; Molina-Ruiz, M.;
Mondal, C.; Mondin, M.; Montani, M.; Moore, C. J.; Moragues, J.;
Moraru, D.; Morawski, F.; More, A.; More, S.; Moreno, C.; Moreno,
G.; Mori, Y.; Morisaki, S.; Morisue, N.; Moriwaki, Y.; Mours, B.;
Mow-Lowry, C. M.; Mozzon, S.; Muciaccia, F.; Mukherjee, D.; Mukherjee,
Soma; Mukherjee, Subroto; Mukherjee, Suvodip; Mukund, N.; Mullavey,
A.; Munch, J.; Muñiz, E. A.; Murray, P. G.; Muusse, S.; Nadji,
S. L.; Nagano, K.; Nagar, A.; Nagar, T.; Nakamura, K.; Nakano, H.;
Nakano, M.; Nakayama, Y.; Napolano, V.; Nardecchia, I.; Narikawa,
T.; Narola, H.; Naticchioni, L.; Nayak, R. K.; Neil, B. F.; Neilson,
J.; Nelson, A.; Nelson, T. J. N.; Nery, M.; Neubauer, P.; Neunzert,
A.; Ng, K. Y.; Ng, S. W. S.; Nguyen, C.; Nguyen, P.; Nguyen, T.;
Nguyen Quynh, L.; Ni, J.; Ni, W. -T.; Nichols, S. A.; Nieradka, G.;
Nishimoto, T.; Nishizawa, A.; Nissanke, S.; Nitoglia, E.; Niu, W.;
Nocera, F.; Norman, M.; North, C.; Notte, J.; Novak, J.; Nozaki,
S.; Nurbek, G.; Nuttall, L. K.; Obayashi, Y.; Oberling, J.; O'Brien,
B. D.; O'Dell, J.; Oelker, E.; Oertel, M.; Ogaki, W.; Oganesyan, G.;
Oh, J. J.; Oh, K.; Oh, S. H.; O'Hanlon, T.; Ohashi, M.; Ohashi, T.;
Ohkawa, M.; Ohme, F.; Ohta, H.; Okutani, Y.; Oliveri, R.; Olivetto, C.;
Oohara, K.; Oram, R.; O'Reilly, B.; Ormiston, R. G.; Ormsby, N. D.;
Orselli, M.; O'Shaughnessy, R.; O'Shea, E.; Oshino, S.; Ossokine,
S.; Osthelder, C.; Otabe, S.; Ottaway, D. J.; Overmier, H.; Pace,
A. E.; Pagano, G.; Pagano, R.; Pagliaroli, G.; Pai, A.; Pai, S. A.;
Pal, S.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pan, K. -C.;
Panda, P. K.; Pang, P. T. H.; Pannarale, F.; Pant, B. C.; Panther,
F. H.; Paoletti, F.; Paoli, A.; Paolone, A.; Pappas, G.; Parisi, A.;
Park, J.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.;
Passuello, D.; Patel, M.; Patel, N. R.; Pathak, M.; Patricelli, B.;
Patron, A. S.; Paul, S.; Payne, E.; Pedraza, M.; Pedurand, R.; Pegna,
R.; Pegoraro, M.; Pele, A.; Peña Arellano, F. E.; Penano, S.; Penn,
S.; Perego, A.; Pereira, A.; Pereira, T.; Perez, C. J.; Périgois,
C.; Perkins, C. C.; Perreca, A.; Perriès, S.; Perry, J. W.; Pesios,
D.; Petermann, J.; Pfeiffer, H. P.; Pham, H.; Pham, K. A.; Phukon,
K. S.; Phurailatpam, H.; Piccinni, O. J.; Pichot, M.; Piendibene,
M.; Piergiovanni, F.; Pierini, L.; Pierra, G.; Pierro, V.; Pillant,
G.; Pillas, M.; Pilo, F.; Pinard, L.; Pineda-Bosque, C.; Pinto,
I. M.; Pinto, M.; Piotrzkowski, B. J.; Piotrzkowski, K.; Pirello,
M.; Pitkin, M. D.; Placidi, A.; Placidi, E.; Planas, M. L.; Plastino,
W.; Poggiani, R.; Polini, E.; Pong, D. Y. T.; Ponrathnam, S.; Porter,
E. K.; Posnansky, C.; Poulton, R.; Powell, J.; Pracchia, M.; Pradier,
T.; Prajapati, A. K.; Prasai, K.; Prasanna, R.; Pratten, G.; Principe,
M.; Prodi, G. A.; Prokhorov, L.; Prosposito, P.; Prudenzi, L.; Puecher,
A.; Punturo, M.; Puosi, F.; Puppo, P.; Pürrer, M.; Qi, H.; Quartey,
N.; Quetschke, V.; Quinonez, P. J.; Quitzow-James, R.; Raab, F. J.;
Raaijmakers, G.; Radkins, H.; Radulesco, N.; Raffai, P.; Rail, S. X.;
Raja, S.; Rajan, C.; Ramirez, K. E.; Ramirez, T. D.; Ramos-Buades, A.;
Rana, D.; Rana, J.; Rangnekar, P. R.; Rapagnani, P.; Ray, A.; Raymond,
V.; Raza, N.; Razzano, M.; Read, J.; Regimbau, T.; Rei, L.; Reid, S.;
Reid, S. W.; Reinhard, M.; Reitze, D. H.; Relton, P.; Renzini, A.;
Rettegno, P.; Revenu, B.; Reyes, J.; Reza, A.; Rezac, M.; Rezaei,
A. S.; Ricci, F.; Richards, D.; Richardson, J. W.; Richardson, L.;
Riles, K.; Rinaldi, S.; Robertson, C.; Robertson, N. A.; Robie, R.;
Robinet, F.; Rocchi, A.; Rodriguez, S.; Rolland, L.; Rollins, J. G.;
Romanelli, M.; Romano, R.; Romel, C. L.; Romero, A.; Romero-Shaw,
I. M.; Romie, J. H.; Ronchini, S.; Roocke, T. J.; Rosa, L.; Rose,
C. A.; Rosińska, D.; Ross, M. P.; Rossello, M.; Rowan, S.; Rowlinson,
S. J.; Roy, Santosh; Roy, Soumen; Royzman, A.; Rozza, D.; Ruggi,
P.; Ruiz-Rocha, K.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadiq, J.;
Saffarieh, P.; Saha, S.; Saito, Y.; Sakai, K.; Sakellariadou, M.;
Sakon, S.; Salafia, O. S.; Salces-Carcoba, F.; Salconi, L.; Saleem,
M.; Salemi, F.; Sallé, M.; Samajdar, A.; Sanchez, E. J.; Sanchez,
J. H.; Sanchez, L. E.; Sanchis-Gual, N.; Sanders, J. R.; Sanuy, A.;
Saravanan, T. R.; Sarin, N.; Sasli, A.; Sassolas, B.; Satari, H.;
Sathyaprakash, B. S.; Sauter, O.; Savage, R. L.; Savant, V.; Sawada,
T.; Sawant, H. L.; Sayah, S.; Schaetzl, D.; Scheel, M.; Scheuer, J.;
Schiworski, M. G.; Schmidt, P.; Schmidt, S.; Schnabel, R.; Schneewind,
M.; Schofield, R. M. S.; Schönbeck, A.; Schulte, B. W.; Schutz, B. F.;
Schwartz, E.; Scott, J.; Scott, S. M.; Seglar-Arroyo, M.; Sekiguchi,
Y.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Seo, E. G.; Sequino,
V.; Sergeev, A.; Servignat, G.; Setyawati, Y.; Shaffer, T.; Shahriar,
M. S.; Shaikh, M. A.; Shams, B.; Shao, L.; Sharma, A.; Sharma, P.;
Shawhan, P.; Shcheblanov, N. S.; Sheela, A.; Sheridan, E.; Shikano,
Y.; Shikauchi, M.; Shimizu, H.; Shimode, K.; Shinkai, H.; Shishido,
T.; Shoda, A.; Shoemaker, D. H.; Shoemaker, D. M.; ShyamSundar, S.;
Sieniawska, M.; Sigg, D.; Silenzi, L.; Singer, L. P.; Singh, D.; Singh,
M. K.; Singh, N.; Singha, A.; Sintes, A. M.; Sipala, V.; Skliris,
V.; Slagmolen, B. J. J.; Slaven-Blair, T. J.; Smetana, J.; Smith,
J. R.; Smith, L.; Smith, R. J. E.; Soldateschi, J.; Somala, S. N.;
Somiya, K.; Song, I.; Soni, K.; Soni, S.; Sordini, V.; Sorrentino, F.;
Sorrentino, N.; Soulard, R.; Souradeep, T.; Spagnuolo, V.; Spencer,
A. P.; Spera, M.; Spinicelli, P.; Srivastava, A. K.; Srivastava,
V.; Stachie, C.; Stachurski, F.; Steer, D. A.; Steinlechner, J.;
Steinlechner, S.; Stergioulas, N.; Stops, D. J.; Strain, K. A.; Strang,
L. C.; Stratta, G.; Strong, M. D.; Strunk, A.; Sturani, R.; Stuver,
A. L.; Suchenek, M.; Sudhagar, S.; Sugimoto, R.; Suh, H. G.; Sullivan,
A. G.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Sur, A.; Suresh, J.;
Sutton, P. J.; Suzuki, Takamasa; Suzuki, Takanori; Suzuki, Toshikazu;
Swinkels, B. L.; Syx, A.; Szczepańczyk, M. J.; Szewczyk, P.; Tacca,
M.; Tagoshi, H.; Tait, S. C.; Takahashi, H.; Takahashi, R.; Takano,
S.; Takeda, H.; Takeda, M.; Talbot, C. J.; Talbot, C.; Tamanini,
N.; Tanaka, K.; Tanaka, Taiki; Tanaka, Takahiro; Tanasijczuk, A. J.;
Tanioka, S.; Tanner, D. B.; Tao, D.; Tao, L.; Tapia, R. D.; Tapia San
Martín, E. N.; Taranto, C.; Taruya, A.; Tasson, J. D.; Tenorio, R.;
Terhune, J. E. S.; Terkowski, L.; Themann, H.; Thirugnanasambandam,
M. P.; Thomas, M.; Thomas, P.; Thomas, S.; Thompson, D.; Thompson,
E. E.; Thompson, J. E.; Thondapu, S. R.; Thorne, K. A.; Thrane, E.;
Tiwari, Shubhanshu; Tiwari, Srishti; Tiwari, V.; Toivonen, A. M.;
Tolley, A. E.; Tomaru, T.; Tomura, T.; Tonelli, M.; Torres-Forné,
A.; Torrie, C. I.; Tosta e Melo, I.; Tournefier, E.; Töyrä, D.;
Trapananti, A.; Travasso, F.; Traylor, G.; Trenado, J.; Trevor, M.;
Tringali, M. C.; Tripathee, A.; Troiano, L.; Trovato, A.; Trozzo,
L.; Trudeau, R. J.; Tsai, D.; Tsang, K. W.; Tsang, T.; Tsao, J-S.;
Tse, M.; Tso, R.; Tsuchida, S.; Tsukada, L.; Tsuna, D.; Tsutsui,
T.; Turbang, K.; Turconi, M.; Turski, C.; Tuyenbayev, D.; Ubach,
H.; Ubhi, A. S.; Uchikata, N.; Uchiyama, T.; Udall, R. P.; Ueda,
A.; Uehara, T.; Ueno, K.; Ueshima, G.; Unnikrishnan, C. S.; Urban,
A. L.; Ushiba, T.; Utina, A.; Vahlbruch, H.; Vaidya, N.; Vajente,
G.; Vajpeyi, A.; Valdes, G.; Valentini, M.; Vallero, S.; Valsan,
V.; van Bakel, N.; van Beuzekom, M.; van Dael, M.; van den Brand,
J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; Van de Walle, A.;
van Dongen, J.; van Haevermaet, H.; van Heijningen, J. V.; Vanosky,
J.; van Putten, M. H. P. M.; van Ranst, Z.; van Remortel, N.; Vardaro,
M.; Vargas, A. F.; Varma, V.; Vasúth, M.; Vecchio, A.; Vedovato, G.;
Veitch, J.; Veitch, P. J.; Venneberg, J.; Venugopalan, G.; Verdier,
P.; Verkindt, D.; Verma, P.; Verma, Y.; Vermeulen, S. M.; Veske, D.;
Vetrano, F.; Viceré, A.; Vidyant, S.; Viets, A. D.; Vijaykumar, A.;
Villa-Ortega, V.; Vinet, J. -Y.; Virtuoso, A.; Vitale, S.; Vocca, H.;
von Reis, E. R. G.; von Wrangel, J. S. A.; Vorvick, C.; Vyatchanin,
S. P.; Wade, L. E.; Wade, M.; Wagner, K. J.; Walet, R. C.; Walker, M.;
Wallace, G. S.; Wallace, L.; Wang, J.; Wang, J. Z.; Wang, W. H.; Ward,
R. L.; Warner, J.; Was, M.; Washimi, T.; Washington, N. Y.; Watada,
K.; Watarai, D.; Watchi, J.; Wayt, K. E.; Weaver, B.; Weaving, C. R.;
Webster, S. A.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Weller,
C. M.; Weller, R. A.; Wellmann, F.; Wen, L.; Weßels, P.; Wette, K.;
Whelan, J. T.; White, D. D.; Whiting, B. F.; Whittle, C.; Wilk, O. S.;
Wilken, D.; Williams, C. E.; Williams, D.; Williams, M. J.; Williamson,
A. R.; Willis, J. L.; Willke, B.; Wipf, C. C.; Woan, G.; Woehler, J.;
Wofford, J. K.; Wojtowicz, I. A.; Wong, D.; Wong, I. C. F.; Wright,
M.; Wu, C.; Wu, D. S.; Wu, H.; Wysocki, D. M.; Xiao, L.; Yadav, N.;
Yamada, T.; Yamamoto, H.; Yamamoto, K.; Yamamoto, T.; Yamashita,
K.; Yamazaki, R.; Yang, F. W.; Yang, K. Z.; Yang, L.; Yang, Y. -C.;
Yang, Y.; Yang, Yang; Yap, M. J.; Yeeles, D. W.; Yeh, S. -W.; Yelikar,
A. B.; Yokoyama, J.; Yokozawa, T.; Yoo, J.; Yoshioka, T.; Yu, Hang;
Yu, Haocun; Yuzurihara, H.; Zadrożny, A.; Zanolin, M.; Zeidler, S.;
Zelenova, T.; Zendri, J. -P.; Zevin, M.; Zhan, M.; Zhang, H.; Zhang,
J.; Zhang, L.; Zhang, R.; Zhang, T.; Zhang, Y.; Zhao, C.; Zhao, G.;
Zhao, Y.; Zhao, Yue; Zheng, Y.; Zhou, R.; Zhu, X. J.; Zhu, Z. -H.;
Zimmerman, A. B.; Zucker, M. E.; Zweizig, J.
Bibcode: 2022arXiv220902863T
Altcode:
We present the results of a model-based search for continuous
gravitational waves from the low-mass X-ray binary Scorpius X-1 using
LIGO detector data from the third observing run of Advanced LIGO,
Advanced Virgo and KAGRA. This is a semicoherent search which uses
details of the signal model to coherently combine data separated
by less than a specified coherence time, which can be adjusted to
balance sensitivity with computing cost. The search covered a range of
gravitational-wave frequencies from 25Hz to 1600Hz, as well as ranges
in orbital speed, frequency and phase determined from observational
constraints. No significant detection candidates were found, and upper
limits were set as a function of frequency. The most stringent limits,
between 100Hz and 200Hz, correspond to an amplitude h0 of about 1e-25
when marginalized isotropically over the unknown inclination angle
of the neutron star's rotation axis, or less than 4e-26 assuming the
optimal orientation. The sensitivity of this search is now probing
amplitudes predicted by models of torque balance equilibrium. For
the usual conservative model assuming accretion at the surface of
the neutron star, our isotropically-marginalized upper limits are
close to the predicted amplitude from about 70Hz to 100Hz; the limits
assuming the neutron star spin is aligned with the most likely orbital
angular momentum are below the conservative torque balance predictions
from 40Hz to 200Hz. Assuming a broader range of accretion models, our
direct limits on gravitational-wave amplitude delve into the relevant
parameter space over a wide range of frequencies, to 500Hz or more.
Title: The SAMI Galaxy Survey: the drivers of gas and stellar
metallicity differences in galaxies
Authors: Fraser-McKelvie, A.; Cortese, L.; Groves, B.; Brough, S.;
Bryant, J.; Catinella, B.; Croom, S.; D'Eugenio, F.; López-Sánchez,
Á. R.; van de Sande, J.; Sweet, S.; Vaughan, S.; Bland-Hawthorn,
J.; Lawrence, J.; Lorente, N.; Owers, M.
Bibcode: 2022MNRAS.510..320F
Altcode: 2021MNRAS.tmp.3132F; 2021arXiv211111627F
The combination of gas-phase oxygen abundances and stellar metallicities
can provide us with unique insights into the metal enrichment
histories of galaxies. In this work, we compare the stellar and
gas-phase metallicities measured within a 1Re aperture for
a representative sample of 472 star-forming galaxies extracted from the
SAMI Galaxy Survey. We confirm that the stellar and interstellar medium
(ISM) metallicities are strongly correlated, with scatter ~3 times
smaller than that found in previous works, and that integrated stellar
populations are generally more metal-poor than the ISM, especially in
low-mass galaxies. The ratio between the two metallicities strongly
correlates with several integrated galaxy properties including stellar
mass, specific star formation rate, and a gravitational potential
proxy. However, we show that these trends are primarily a consequence
of: (a) the different star formation and metal enrichment histories
of the galaxies, and (b) the fact that while stellar metallicities
trace primarily iron enrichment, gas-phase metallicity indicators are
calibrated to the enrichment of oxygen in the ISM. Indeed, once both
metallicities are converted to the same 'element base' all of our trends
become significantly weaker. Interestingly, the ratio of gas to stellar
metallicity is always below the value expected for a simple closed-box
model, which requires that outflows and inflows play an important role
in the enrichment history across our entire stellar mass range. This
work highlights the complex interplay between stellar and gas-phase
metallicities and shows how care must be taken in comparing them to
constrain models of galaxy formation and evolution.
Title: An Objective Definition of Habitable Space and Application
to Modeling Water Activity from Geochemistry
Authors: Bowman, J. S.; Bastuba, A.; Som, S.; Plattner, T.; Pontefract,
A.; Doran, P.; Buffo, J.; Lawrence, J.; Schmidt, B.; O. A. S. T. Team
Bibcode: 2021LPICo2614.6047B
Altcode:
We developed an approach based on a self-organizing map to objectively
characterize habitability. We extended this approach to develop a
model for predicting water activity from physico-chemical parameters.
Title: British Columbia's Unassuming Planetary Laboratory: How a
Handful of Frozen Saline Lakes can Help Us Understand Brines Across
the Solar System
Authors: Buffo, J. J.; Brown, E. K.; Pontefract, A.; Schmidt, B. E.;
Klempay, B.; Lawrence, J.; Bowman, J.; Grantham, M.; Glass, J. B.;
Plattner, T.; Chivers, C.; Doran, P.; Meyer, C. R.; Barklage, M. E.;
Fluegel, B.
Bibcode: 2021LPICo2614.6020B
Altcode:
The physicochemical properties of compositionally diverse ice-brine
analog systems - constraining their habitability, their essential role
in validating numerical models, and implications for the geophysics
and astrobiology of planetary ice-brine environments.
Title: TopEFT/topcoffea: TopCoffea 0.1
Authors: Basnet, Aashwin; Bloom, Kenneth; Canelli, Florencia; Sanchez
Cruz, Sergio; Palencia Cortezon, Jose Enrique; González Fernández,
Juan Rodrigo; Trapote Fernandez, Andrea; Goldouzian, Reza; Alvarez
Gonzalez, Barbara; Hildreth, Michael; Lannon, Kevin; Lawrence, John;
Liechti, Sascha Pascal; Mcgrady, Christopher Edward; Mohrman, Kelci;
Nelson, Hannah; Tovar, Benjamin; Wan, Yuyi; Wightman, Andrew; Winer,
Brian; Yan, Furong; Yates, Brent R.; Yockey, Henry; Zarucki, Mateusz
Bibcode: 2021zndo...5258003B
Altcode:
Initial release for https://zenodo.org/
Title: The SAMI Galaxy Survey: the role of disc fading and progenitor
bias in kinematic transitions
Authors: Croom, S. M.; Taranu, D. S.; van de Sande, J.; Lagos,
C. D. P.; Harborne, K. E.; Bland-Hawthorn, J.; Brough, S.; Bryant,
J. J.; Cortese, L.; Foster, C.; Goodwin, M.; Groves, B.; Khalid, A.;
Lawrence, J.; Medling, A. M.; Richards, S. N.; Owers, M. S.; Scott,
N.; Vaughan, S. P.
Bibcode: 2021MNRAS.505.2247C
Altcode: 2021arXiv210510179C
We use comparisons between the Sydney-AAO Multi-object Integral
Field Spectrograph (SAMI) Galaxy Survey and equilibrium galaxy models
to infer the importance of disc fading in the transition of spirals
into lenticular (S0) galaxies. The local S0 population has both higher
photometric concentration and lower stellar spin than spiral galaxies of
comparable mass and we test whether this separation can be accounted
for by passive aging alone. We construct a suite of dynamically
self-consistent galaxy models, with a bulge, disc, and halo using the
GALACTICS code. The dispersion-dominated bulge is given a uniformly old
stellar population, while the disc is given a current star formation
rate putting it on the main sequence, followed by sudden instantaneous
quenching. We then generate mock observables (r-band images, stellar
velocity, and dispersion maps) as a function of time since quenching
for a range of bulge/total (B/T) mass ratios. The disc fading leads
to a decline in measured spin as the bulge contribution becomes
more dominant, and also leads to increased concentration. However,
the quantitative changes observed after 5 Gyr of disc fading cannot
account for all of the observed difference. We see similar results if
we instead subdivide our SAMI Galaxy Survey sample by star formation
(relative to the main sequence). We use EAGLE simulations to also take
into account progenitor bias, using size evolution to infer quenching
time. The EAGLE simulations suggest that the progenitors of current
passive galaxies typically have slightly higher spin than present day
star-forming disc galaxies of the same mass. As a result, progenitor
bias moves the data further from the disc fading model scenario,
implying that intrinsic dynamical evolution must be important in the
transition from star-forming discs to passive discs.
Title: British Columbia's Hypersaline Lakes as Model Analogs for
Planetary Ice-Brine Systems
Authors: Brown, E. K.; Buffo, J. J.; Pontefract, A.; Klempay, B.;
Grantham, M.; Glass, J.; Lawrence, J.; Plattner, T.; Doran, P.;
Bowman, J. S.; Schmidt, B. E.; OAST Team
Bibcode: 2021LPICo2595.8109B
Altcode:
Biogeochemical analysis of central British Columbia's hypersaline
lakes. Presented data has important astrobiological implications for
ice-brine systems on other planetary bodies like Europa, Enceladus,
and Mars.
Title: A SAMI and MaNGA view on the stellar kinematics of galaxies
on the star-forming main sequence
Authors: Fraser-McKelvie, A.; Cortese, L.; van de Sande, J.; Bryant,
J. J.; Catinella, B.; Colless, M.; Croom, S. M.; Groves, B.; Medling,
A. M.; Scott, N.; Sweet, S. M.; Bland-Hawthorn, J.; Goodwin, M.;
Lawrence, J.; Lorente, N.; Owers, M. S.; Richards, S. N.
Bibcode: 2021MNRAS.503.4992F
Altcode: 2021arXiv210213342F; 2021MNRAS.tmp..596F
Galaxy internal structure growth has long been accused of inhibiting
star formation in disc galaxies. We investigate the potential physical
connection between the growth of dispersion-supported stellar structures
(e.g. classical bulges) and the position of galaxies on the star-forming
main sequence at z ~ 0. Combining the might of the SAMI and MaNGA
galaxy surveys, we measure the λRe spin parameter for
3289 galaxies over $9.5 \lt \log M_{\star } [\rm {M}_{\odot }] \lt
12$. At all stellar masses, galaxies at the locus of the main sequence
possess λRe values indicative of intrinsically flattened
discs. However, above $\log M_{\star }[\rm {M}_{\odot }]\sim 10.5$ where
the main sequence starts bending, we find tantalizing evidence for an
increase in the number of galaxies with dispersion-supported structures,
perhaps suggesting a connection between bulges and the bending of the
main sequence. Moving above the main sequence, we see no evidence of any
change in the typical spin parameter in galaxies once gravitationally
interacting systems are excluded from the sample. Similarly, up
to 1 dex below the main sequence, λRe remains roughly
constant and only at very high stellar masses ($\log M_{\star }[\rm
{M}_{\odot }]\gt 11$), do we see a rapid decrease in λRe
once galaxies decline in star formation activity. If this trend is
confirmed, it would be indicative of different quenching mechanisms
acting on high- and low-mass galaxies. The results suggest that whilst
a population of galaxies possessing some dispersion-supported structure
is already present on the star-forming main sequence, further growth
would be required after the galaxy has quenched to match the kinematic
properties observed in passive galaxies at z ~ 0.
Title: VizieR Online Data Catalog: Observed transitions of
CH3OH and CH3CHO (H
Authors: Holdship, J.; Viti, S.; Codella, C.; Rawlings, J.;
Jimenez-Serra, I.; Ayalew, Y.; Curtis, J.; Habib, A.; Lawrence, J.;
Warsame, S.; Horn, S.
Bibcode: 2021yCat..18800138H
Altcode:
Observations of eight outflow sources were obtained using the IRAM-30m
telescope. The observations contain two frequency ranges, the first
from 96 to 104GHz and the second from 152 to 176GHz. Observations,
taken using the IRAM-30m telescope's EMIR receivers and the Fourier
Transform Spectrometer back end, were carried out between 2016 June
2nd and 4th in wobbler switching mode. (2 data files).
Title: The MANIFEST pre-concept design
Authors: Lawrence, J.; Ben-Ami, S.; Braulio, A.; Colless, M.; Contos,
A.; DePoy, D.; Faes, D.; Gillingham, P.; Goodwin, M.; Houston, E.;
Kuehn, K.; Lacombe, C.; Lorente, N.; Mali, S.; Marshall, J.; McGregor,
H.; Millan-Gabet, R.; Nichani, V.; Neves Hartmann, V.; O'Brien, E.;
Oliveira, C.; Ortolan, H.; Pires, P.; Ribeiro, R.; Saunders, W.;
Schmidt, L.; Souza, A.; Szentgyorgyi, A.; Waller, L.; Zafar, T.;
Zheng, J.
Bibcode: 2020SPIE11447E..28L
Altcode:
MANIFEST is a multi-object fibre positioner for the Giant Magellan
Telescope that uses `Starbug' robots to accurately position fibre
units across the telescope's focal plane. MANIFEST, when coupled to
the telescope's planned seeing-limited instruments, GMACS and GCLEF,
offers access to: larger fields of view; higher multiplex gains;
versatile focal plane reformatting of the focal plane via multiple
integral-field-units; increased spectral resolution using image-slicers;
the capability for simultaneous observations with multiple instruments;
the possibility of a gravity-invariant spectrograph mounting; the
potential for OH suppression via fiber systems in the near-infrared;
and the versatility of adding new instruments in the future. We have
now completed the pre-concept phase for MANIFEST. This phase has
focused on developing the science case and requirements, further
developing high risk aspects of the instrument design, designing
the opto-mechanical interfaces to the GMACS and GCLEF instruments,
and detailing the interfaces to the GMT.
Title: ROV Icefin at Ross Ice Shelf Grounding Zone: 5 km of ice,
ocean, seafloor, and crevasse exploration
Authors: Lawrence, J.; Schmidt, B.; Washam, P.; Hulbe, C. L.; Horgan,
H. J.; Stevens, C.; Dunbar, G. B.; Meister, M. R.; Hurwitz, B.;
Quartini, E.; Dichek, D.; Spears, A.; Mullen, A. D.; Bryson, F. E.
Bibcode: 2020AGUFMC019...07L
Altcode:
Ice shelf grounding zones are important regions where interactions
between sediment, ice, and ocean combine to influence cavity geometry,
ice flux, and water circulation. In collaboration with the New Zealand
Antarctic Research Institute-funded Ross Ice Shelf Programme and the
MBIE Antarctic Science Platform, from December 17-21 2019 we deployed
Icefin, a remotely operated underwater vehicle (ROV), through a borehole
into the ocean lens three kilometers downstream of the Ross Ice Shelf
grounding zone (Kamb Ice Stream HWD-1 Site). Icefin is supported by
the NASA Ross Ice Shelf and Europa Underwater Probe (RISE UP) project,
and for this work was equipped with sensors to measure water velocity,
salinity, temperature, oxygen, organics, turbidity, chlorophyll, and pH,
along with multiple sonars and cameras. We observed a 30 m thick
water column stratified into two layers. The fresher upper layer was
within 0.1°C of the freezing point and had slightly elevated turbidity
and dissolved oxygen levels relative to the lower layer, which was
more saline and warmer, within 0.3 °C of the freezing point. 1.5 km
of ice flow parallel transects mapped five 35-50 m tall asymmetric
crevasses. Investigation into a crevasse identified supercooled water
and active marine ice formation in the upper 10 m. The entire ice base
exhibited scalloped cusps indicative of melting, including one region of
sediment-rich basal ice. The seafloor exhibited two dominant types- 1)
fine sediment drape with sub-meter scale ridges above ice flow-parallel
fluting, which was typical beneath meteoric ice regions, and 2)
smooth, ridge free seafloor with abundant cm-scale debris beneath the
sediment-laden basal ice region. Two 20-30 m wide sections of parallel,
sub-meter tall seafloor ridges had similar strike and dimensions to
basal crevasses, both transverse to ice flow. These observations help
to understand grounding zone dynamics, and more specifically Kamb Ice
Stream's stagnation history and potential to reactivate and increase
the rate of sea level rise. Direct observations of marine ice formation
in a basal crevasse inform ice shelf stability, modeling, and analogous
processes on other ocean worlds.
Title: Vertical Entry Robot for Navigating Europa (VERNE) - A
Mission Concept and Identification of Technologies Needed to Access
Europa's Ocean
Authors: Bryson, F. E.; Meister, M. R.; Burnett, J.; Chivers, C.;
Colón, B.; Daniel, N.; Dichek, D.; Hanna, A. M.; Hodges, A. L.;
Hughson, K.; Hurwitz, B.; Lawrence, J.; Mullen, A. D.; Nassif, M.;
Pierson, S.; Plattner, T.; Rapoport, S.; Spears, A.; Spiers, E. M.;
Szot, P.; Tomar, Y.; Wiley, B.; Lightsey, E. G.; Schmidt, B. E.
Bibcode: 2020AGUFMP052...04B
Altcode:
The liquid water within or beneath the ice shells of Ocean Worlds
are promising locations in the solar system for the search for life
beyond Earth, making them compelling targets for future missions. The
SESAME-funded Vertical Entry Robot for Navigating Europa (VERNE) project
is a mission concept for autonomous penetration and operation within
Europa's ice shell and ocean, to deliver a package through the ice of
Europa that is capable of sampling material and profiling for chemical
and physical properties and indications of life within the ice and the
ocean. The goals of the study also include identifying key technologies
that are currently available, or that require near-term investments to
enable sub-surface access in the coming decades. The mission concept
is novel in its approach to operations, leveraging experience with
environments on Earth. As the vehicle descends through the ice shell,
it will collect and analyze melted water samples at planned intervals
and relay data through optical fiber cable and wireless repeaters
to the surface lander. Unique to the VERNE concept, before reaching
the subsurface ocean, the vehicle will release an anchor in the ice
that allows control of its descent and profiling of approximately
100 m of the upper ocean and ice interface, which is a region with
high potential for harboring signs of life on Europa. Here
we present the mission concept and findings thus far, highlighting
the major systems that support the mission and the novel approach we
envision for sample handling and profiling operations, and commenting
on mission requirements. In addition, we have identified and begun an
investigation into key developments necessary to enable such a mission:
by using a representative instrument suite we have developed a concept
of operations of the sample handling system, as well as a design for a
prototype that integrates sample processing; explored the components
that support anchoring the vehicle and profiling the upper ocean and
ice interface; and developed models of acoustic communication through
the ice shell that would enable data transmission.
Title: VERNE Sample Intake and Processing (SIP): Investigation and
Development of Liquid Water Sampling for Subsurface Probe on Europa
Authors: Spiers, E. M.; Bryson, F. E.; Mullen, A. D.; Chivers, C.;
Hanna, A. M.; Hughson, K.; Lawrence, J.; Plattner, T.; Ingall, E. D.;
Carr, C. E.; Meister, M. R.; Lightsey, E. G.; Schmidt, B.
Bibcode: 2020AGUFMP044.0013S
Altcode:
Jupiter's moon Europa contains a global subsurface ocean beneath
its ice shell and is an exciting target for the search for life. The
Vertical Entry Robot for Navigating Europa (VERNE) project is exploring
the technology necessary to deliver a vehicle through Europa's ice
shell to access subsurface liquid water either below or within the
shell. VERNE Sample Handling System includes the ability to collect
and process liquid water samples and deliver these samples to a
representative science suite. We used a representative science suite,
inclusive of space-flown instruments, oceanographic instruments,
and instruments focused on life detection, to prove the concept
for the VERNE system. By sampling throughout the ice shell into
the subsurface ocean, VERNE would probe the Europan interior for
evidence of past and/or extant life. Through the representative
science suite, we have developed requirements for sample handling
and processing such that the system could be robust to the choice of
future instruments. Instrument requirements including sample volume,
pressure, flow rate, temperature, etc, may vary. Thus, we developed
a design prototype and concept of operations for the sample handling
system that incorporates variable sample processing to accommodate a
wide range of instrumentation. Technologies for sample processing that
require development before flight were also identified, including
a subset of components of the system that will be developed and
tested during the study. One of the primary challenges for subsurface
Europa or ocean worlds missions is the potential wide range of sample
salinities and composition, due to the unknown salt content of Europa's
interior. Salts are capable of not only clogging fluidic systems, but
also altering measurement capabilities of instruments such as mass
spectrometers. Therefore, designing a system with the capability to
intake and handle highly saline fluids has been a primary focus. Here we present the design of this sample handling system that will
enable the analysis of water samples through Europa's ice shell and
in its ocean, as well as preliminary results from tests of select
components of the system and its sample processing capabilities.
Title: A Submersible Digital Holographic Microscope for In Situ
Microbial Imaging
Authors: Mullen, A. D.; Snyder, C.; Schmidt, B.; Dichek, D.; Lawrence,
J.; Meister, M. R.; Bryson, F. E.; Nadeau, J. L.; Wallace, J. K.;
Lindensmith, C. A.
Bibcode: 2020AGUFMP044.0011M
Altcode:
A microscope for life detection is a top candidate for inclusion
in biological instrument packages for potential ocean world
missions. Holographic microscopy offers several advantages over
traditional light microscopy including image reconstructions over
a 3D volume and phase information retrieval. This approach enables
non-destructive detection of microbes based on morphology, motility,
and physical properties such as density and index of refraction. Here
we present a submersible Digital Holographic Microscope (DHM) developed
for in situ operation and microbe detection in terrestrial oceans,
including under-ice polar and deep-sea environments. This microscope
uses an optical design being developed for potential planetary missions
and offers a means for testing instrumentation as well as for conducting
biological studies in analog terrestrial settings.
Title: VizieR Online Data Catalog: SAMI Galaxy Survey. Gas surface
densities (Federrath+, 2017)
Authors: Federrath, C.; Salim, D. M.; Medling, A. M.; Davies, R. L.;
Yuan, T.; Bian, F.; Groves, B. A.; Ho, I. -T.; Sharp, R.; Kewley,
L. J.; Sweet, S. M.; Richards, S. N.; Bryant, J. J.; Brough, S.;
Croom, S.; Scott, N.; Lawrence, J.; Konstantopoulos, I.; Goodwin, M.
Bibcode: 2020yCat..74683965F
Altcode:
We presented a new method to estimate the molecular gas column
density ({Sigma}gas) of a galaxy using only optical IFS
data, by inverting the star formation relation derived in Salim et
al., 2015ApJ...806L..36S. We apply our new method to estimate
{Sigma}gas for star-forming and composite/AGN/shock galaxies
classified and observed in the SAMI Galaxy Survey internal data release
version 0.9. The SAMI (Croom et al., 2012MNRAS.421..872C). (2
data files).
Title: CESM-release-cesm2.1.2
Authors: Danabasoglu; Lamarque; Bacmeister; Bailey; DuVivier;
Edwards; Emmons; Fasullo; Garcia; Gettelman; Hannay; Holland; Large;
Lauritzen; Lawrence; Lenaerts; Lindsay; Lipscomb; Mills; Neale; Oleson;
Otto-Bliesner; Phillips; Sacks; Tilmes; Kampenhout, Van; Vertenstein;
Bertini; Dennis; Deser; Fischer; Fox-Kemper; Kay; Kinnison; Kushner;
Larson; Long; Mickelson; Moore; Nienhouse; Polvani; Rasch; Strand
Bibcode: 2020zndo...3895328D
Altcode:
The Community Earth System Model release version cesm2.1.2
Title: CESM-release-cesm2.1.1
Authors: Danabasoglu; Lamarque; Bacmeister; Bailey; DuVivier;
Edwards; Emmons; Fasullo; Garcia; Gettelman; Hannay; Holland; Large;
Lauritzen; Lawrence; Lenaerts; Lindsay; Lipscomb; Mills; Neale; Oleson;
Otto-Bliesner; Phillips; Sacks; Tilmes; Kampenhout, van; Vertenstein;
Bertini; Dennis; Deser; Fischer; Fox-Kemper; Kay; Kinnison; Kushner;
Larson; Long; Mickelson; Moore; Nienhouse; Polvani; Rasch; Strand
Bibcode: 2019zndo...3895315D
Altcode:
The Community Climate Earth System Model release version cesm2.1.1
Title: VizieR Online Data Catalog: Exoplanets in the Antarctic
sky. II. 116 candidates (Zhang+, 2019)
Authors: Zhang, H.; Yu, Z.; Liang, E.; Yang, M.; Ashley, M. C. B.;
Cui, X.; Du, F.; Fu, J.; Gong, X.; Gu, B.; Hu, Yi; Jiang, P.; Liu,
H.; Lawrence, J.; Liu, Q.; Li, X.; Li, Z.; Ma, B.; Mould, J.; Shang,
Z.; Suntzeff, N. B.; Tao, C.; Tian, Q.; Tinney, C. G.; Uddin, S. A.;
Wang, L.; Wang, S.; Wang, X.; Wei, P.; Wright, D.; Wu, X.; Wittenmyer,
R. A.; Xu, L.; Yang, S. -H.; Yu, Ce; Yuan, X.; Zheng, J.; Zhou, H.;
Zhou, J. -L.; Zhu, Z.
Bibcode: 2019yCat..22400017Z
Altcode:
The CHinese Exoplanet Searching Program from Antarctica (CHESPA)
--described in Paper I; Zhang+, 2018, J/ApJS/240/16 -- has been
running since 2012 using the CSTAR and AST3 (Antarctic Survey
Telescopes times 3) telescopes. To maximize collaboration with TESS
and enhance the scientific importance of our searching program,
we selected 48 target fields close to the South Ecliptic Pole
(RAJ2000=06:00:00,DEJ2000=-66:33:00) and within the TESS' Southern
continuous viewing zone (CVZ). (2 data files).
Title: VizieR Online Data Catalog: Exoplanets in the Antarctic
sky. I. AST3-II DR1 (Zhang+, 2019)
Authors: Zhang, H.; Yu, Z.; Liang, E.; Yang, M.; Ashley, M. C. B.;
Cui, X.; Du, F.; Fu, J.; Gong, X.; Gu, B.; Hu, Yi; Jiang, P.; Liu,
H.; Lawrence, J.; Liu, Q.; Li, X.; Li, Z.; Ma, B.; Mould, J.; Shang,
Z.; Suntzeff, N. B.; Tao, C.; Tian, Q.; Tinney, C. G.; Uddin, S. A.;
Wang, L.; Wang, S.; Wang, X.; Wei, P.; Wright, D.; Wu, X.; Wittenmyer,
R. A.; Xu, L.; Yang, S. -H.; Yu, Ce; Yuan, X.; Zheng, J.; Zhou, H.;
Zhou, J. -L.; Zhu, Z.
Bibcode: 2019yCat..22400016Z
Altcode:
In the austral winters of 2016 and 2017, we used the AST3-II telescope
--located at the Chinese Kunlun station at Dome A, Antarctica-- to
survey a group of selected fields near the southern ecliptic pole
and within the southern continuous viewing zone (CVZ) of Transiting
Exoplanet Survey Satellite (TESS; Ricker+ 2009AAS...21430605R). This first data release contains a data set obtained in the austral
winter of 2016. (3 data files).
Title: 4MOST: Project overview and information for the First Call
for Proposals
Authors: de Jong, R. S.; Agertz, O.; Berbel, A. A.; Aird, J.;
Alexander, D. A.; Amarsi, A.; Anders, F.; Andrae, R.; Ansarinejad,
B.; Ansorge, W.; Antilogus, P.; Anwand-Heerwart, H.; Arentsen, A.;
Arnadottir, A.; Asplund, M.; Auger, M.; Azais, N.; Baade, D.; Baker,
G.; Baker, S.; Balbinot, E.; Baldry, I. K.; Banerji, M.; Barden,
S.; Barklem, P.; Barthélémy-Mazot, E.; Battistini, C.; Bauer, S.;
Bell, C. P. M.; Bellido-Tirado, O.; Bellstedt, S.; Belokurov, V.;
Bensby, T.; Bergemann, M.; Bestenlehner, J. M.; Bielby, R.; Bilicki,
M.; Blake, C.; Bland-Hawthorn, J.; Boeche, C.; Boland, W.; Boller,
T.; Bongard, S.; Bongiorno, A.; Bonifacio, P.; Boudon, D.; Brooks,
D.; Brown, M. J. I.; Brown, R.; Brüggen, M.; Brynnel, J.; Brzeski,
J.; Buchert, T.; Buschkamp, P.; Caffau, E.; Caillier, P.; Carrick,
J.; Casagrande, L.; Case, S.; Casey, A.; Cesarini, I.; Cescutti, G.;
Chapuis, D.; Chiappini, C.; Childress, M.; Christlieb, N.; Church, R.;
Cioni, M. -R. L.; Cluver, M.; Colless, M.; Collett, T.; Comparat, J.;
Cooper, A.; Couch, W.; Courbin, F.; Croom, S.; Croton, D.; Daguisé,
E.; Dalton, G.; Davies, L. J. M.; Davis, T.; de Laverny, P.; Deason,
A.; Dionies, F.; Disseau, K.; Doel, P.; Döscher, D.; Driver, S. P.;
Dwelly, T.; Eckert, D.; Edge, A.; Edvardsson, B.; Youssoufi, D. E.;
Elhaddad, A.; Enke, H.; Erfanianfar, G.; Farrell, T.; Fechner, T.;
Feiz, C.; Feltzing, S.; Ferreras, I.; Feuerstein, D.; Feuillet, D.;
Finoguenov, A.; Ford, D.; Fotopoulou, S.; Fouesneau, M.; Frenk, C.;
Frey, S.; Gaessler, W.; Geier, S.; Gentile Fusillo, N.; Gerhard,
O.; Giannantonio, T.; Giannone, D.; Gibson, B.; Gillingham, P.;
González-Fernández, C.; Gonzalez-Solares, E.; Gottloeber, S.; Gould,
A.; Grebel, E. K.; Gueguen, A.; Guiglion, G.; Haehnelt, M.; Hahn, T.;
Hansen, C. J.; Hartman, H.; Hauptner, K.; Hawkins, K.; Haynes, D.;
Haynes, R.; Heiter, U.; Helmi, A.; Aguayo, C. H.; Hewett, P.; Hinton,
S.; Hobbs, D.; Hoenig, S.; Hofman, D.; Hook, I.; Hopgood, J.; Hopkins,
A.; Hourihane, A.; Howes, L.; Howlett, C.; Huet, T.; Irwin, M.; Iwert,
O.; Jablonka, P.; Jahn, T.; Jahnke, K.; Jarno, A.; Jin, S.; Jofre,
P.; Johl, D.; Jones, D.; Jönsson, H.; Jordan, C.; Karovicova, I.;
Khalatyan, A.; Kelz, A.; Kennicutt, R.; King, D.; Kitaura, F.; Klar,
J.; Klauser, U.; Kneib, J. -P.; Koch, A.; Koposov, S.; Kordopatis, G.;
Korn, A.; Kosmalski, J.; Kotak, R.; Kovalev, M.; Kreckel, K.; Kripak,
Y.; Krumpe, M.; Kuijken, K.; Kunder, A.; Kushniruk, I.; Lam, M. I.;
Lamer, G.; Laurent, F.; Lawrence, J.; Lehmitz, M.; Lemasle, B.; Lewis,
J.; Li, B.; Lidman, C.; Lind, K.; Liske, J.; Lizon, J. -L.; Loveday,
J.; Ludwig, H. -G.; McDermid, R. M.; Maguire, K.; Mainieri, V.; Mali,
S.; Mandel, H.; Mandel, K.; Mannering, L.; Martell, S.; Martinez
Delgado, D.; Matijevic, G.; McGregor, H.; McMahon, R.; McMillan,
P.; Mena, O.; Merloni, A.; Meyer, M. J.; Michel, C.; Micheva, G.;
Migniau, J. -E.; Minchev, I.; Monari, G.; Muller, R.; Murphy, D.;
Muthukrishna, D.; Nandra, K.; Navarro, R.; Ness, M.; Nichani, V.;
Nichol, R.; Nicklas, H.; Niederhofer, F.; Norberg, P.; Obreschkow, D.;
Oliver, S.; Owers, M.; Pai, N.; Pankratow, S.; Parkinson, D.; Paschke,
J.; Paterson, R.; Pecontal, A.; Parry, I.; Phillips, D.; Pillepich,
A.; Pinard, L.; Pirard, J.; Piskunov, N.; Plank, V.; Plüschke, D.;
Pons, E.; Popesso, P.; Power, C.; Pragt, J.; Pramskiy, A.; Pryer,
D.; Quattri, M.; Queiroz, A. B. d. A.; Quirrenbach, A.; Rahurkar,
S.; Raichoor, A.; Ramstedt, S.; Rau, A.; Recio-Blanco, A.; Reiss, R.;
Renaud, F.; Revaz, Y.; Rhode, P.; Richard, J.; Richter, A. D.; Rix,
H. -W.; Robotham, A. S. G.; Roelfsema, R.; Romaniello, M.; Rosario, D.;
Rothmaier, F.; Roukema, B.; Ruchti, G.; Rupprecht, G.; Rybizki, J.;
Ryde, N.; Saar, A.; Sadler, E.; Sahlén, M.; Salvato, M.; Sassolas,
B.; Saunders, W.; Saviauk, A.; Sbordone, L.; Schmidt, T.; Schnurr,
O.; Scholz, R. -D.; Schwope, A.; Seifert, W.; Shanks, T.; Sheinis,
A.; Sivov, T.; Skúladóttir, Á.; Smartt, S.; Smedley, S.; Smith,
G.; Smith, R.; Sorce, J.; Spitler, L.; Starkenburg, E.; Steinmetz,
M.; Stilz, I.; Storm, J.; Sullivan, M.; Sutherland, W.; Swann, E.;
Tamone, A.; Taylor, E. N.; Teillon, J.; Tempel, E.; ter Horst, R.;
Thi, W. -F.; Tolstoy, E.; Trager, S.; Traven, G.; Tremblay, P. -E.;
Tresse, L.; Valentini, M.; van de Weygaert, R.; van den Ancker, M.;
Veljanoski, J.; Venkatesan, S.; Wagner, L.; Wagner, K.; Walcher,
C. J.; Waller, L.; Walton, N.; Wang, L.; Winkler, R.; Wisotzki, L.;
Worley, C. C.; Worseck, G.; Xiang, M.; Xu, W.; Yong, D.; Zhao, C.;
Zheng, J.; Zscheyge, F.; Zucker, D.
Bibcode: 2019Msngr.175....3D
Altcode: 2019arXiv190302464D
We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST),
a new high-multiplex, wide-field spectroscopic survey facility under
development for the four-metre-class Visible and Infrared Survey
Telescope for Astronomy (VISTA) at Paranal. Its key specifications
are: a large field of view (FoV) of 4.2 square degrees and a high
multiplex capability, with 1624 fibres feeding two low-resolution
spectrographs (R = λ/Δλ 6500), and 812 fibres transferring light
to the high-resolution spectrograph (R 20 000). After a description of
the instrument and its expected performance, a short overview is given
of its operational scheme and planned 4MOST Consortium science; these
aspects are covered in more detail in other articles in this edition
of The Messenger. Finally, the processes, schedules, and policies
concerning the selection of ESO Community Surveys are presented,
commencing with a singular opportunity to submit Letters of Intent
for Public Surveys during the first five years of 4MOST operations.
Title: CESM-release-cesm2.1.0
Authors: Danabasoglu; Lamarque; Bacmeister; Bailey; DuVivier;
Edwards; Emmons; Fasullo; Garcia; Gettelman; Hannay; Holland; Large;
Lauritzen; Lawrence; Lenaerts; Lindsay; Lipscomb; Mills; Neale; Oleson;
Otto-Bliesner; Phillips; Sacks; Tilmes; Kampenhout, Van; Vertenstein;
Bertini; Dennis; Deser; Fischer; Fox-Kemper; Kay; Kinnison; Kushner;
Larson; Long; Mickelson; Moore; Nienhouse; Polvani; Rasch; Strand
Bibcode: 2018zndo...3895306D
Altcode:
The Community Earth System Model release version 2.1.0
Title: Life Under Ice: Antarctic Ocean World Analogs with HROV Icefin
and RISE UP
Authors: Lawrence, J.; Schmidt, B. E.; Meister, M. R.; Dichek, D.;
Ramey, C.; Hurwitz, B.; Spears, A.; Mullen, A.; Bryson, F. E.; Lutz,
J. J.; Lawrence, J. P.; Glass, J. B.; Stockton, A. M.; Speller,
N. C.; Cato, M.; Block, D.; Philleo, M.; Bowman, J. S.; Hamerton,
E. K.; Buffo, J.
Bibcode: 2018AGUFM.P21E3402L
Altcode:
Icefin is a 3.5 m long, 24 cm diameter, 1500 m rated hybrid remote or
autonomous underwater vehicle (HROV) developed for sub-ice observations
in Dr. Britney Schmidt's Planetary Habitability and Technology Lab
at Georgia Tech (US). First deployed beneath McMurdo Ice Shelf (MIS)
in 2014, Icefin conducts basal ice, water column, and benthic surveys
through ≥ 35 cm boreholes with a modular oceanographic sensor payload
including CTD, DO, fDOM, turbidity, pH/ORP, ADCP, 2D forward sonar,
altimetry, sidescan, and HD or 4K imaging. With live data streams
via fiber-optic tether, remote or autonomous survey ability, and 5 km
range Icefin provides a novel platform for better understanding ocean
circulation, ice mass balance, and ecosystem diversity in sub-ice
environments. Currently, the Icefin team is conducting Antarctic
fieldwork under the NASA PSTAR-funded RISE UP program (Ross Ice Shelf
and Europa Underwater Probe). RISE UP aims to autonomously characterize
habitability and under-ice environments on broad spatial scales via
robotic platforms toward future exploration of ocean worlds. In addition
to Icefin work, complementary water column profiling to constrain
sub-ice habitability includes CTD profiling, nutrient concentrations,
cell counts, and 16S/18S rRNA gene surveys. Here, we present updates
from an ongoing 2018 Antarctic field season (October - December 2018)
with observations from beneath McMurdo Ice Shelf, McMurdo Sound sea ice,
and nearby Erebus Glacier Tongue of water column structure, benthic
geology, and fauna from the basal ice interface to the seafloor 900
meters below. Continued work includes collaborations with the
Antarctica New Zealand Ross Ice Shelf Programme (2019/20, PI Christina
Hulbe) at Ross Ice Shelf Grounding Zone, and the International Thwaites
Glacier Collaboration with MELT (2019/20, PIs Keith Nicholls, David
Holland). Icefin also serves as a novel oceanographic sensor development
and test platform. Microfluidic cell counting, holographic microscopy,
and onboard ice/sediment/water sampling modules are also currently in
design and assembly phases.
Title: The SAMI Galaxy Survey: gas content and interaction as the
drivers of kinematic asymmetry
Authors: Bloom, J. V.; Croom, S. M.; Bryant, J. J.; Schaefer, A. L.;
Bland-Hawthorn, J.; Brough, S.; Callingham, J.; Cortese, L.; Federrath,
C.; Scott, N.; van de Sande, J.; D'Eugenio, F.; Sweet, S.; Tonini,
C.; Allen, J. T.; Goodwin, M.; Green, A. W.; Konstantopoulos, I. S.;
Lawrence, J.; Lorente, N.; Medling, A. M.; Owers, M. S.; Richards,
S. N.; Sharp, R.
Bibcode: 2018MNRAS.476.2339B
Altcode: 2018MNRAS.tmp..264B; 2018arXiv180106628B
In order to determine the causes of kinematic asymmetry in the Hα
gas in the SAMI (Sydney-AAO Multi-object IFS) Galaxy Survey sample,
we investigate the comparative influences of environment and intrinsic
properties of galaxies on perturbation. We use spatially resolved
Hα velocity fields from the SAMI Galaxy Survey to quantify kinematic
asymmetry (\overline{v_asym}) in nearby galaxies and environmental and
stellar mass data from the Galaxy And Mass Assembly survey. We find
that local environment, measured as distance to nearest neighbour,
is inversely correlated with kinematic asymmetry for galaxies with log
(M*/M⊙) > 10.0, but there is no significant
correlation for galaxies with log (M*/M⊙) <
10.0. Moreover, low-mass galaxies [log (M*/M⊙)
< 9.0] have greater kinematic asymmetry at all separations,
suggesting a different physical source of asymmetry is important
in low-mass galaxies. We propose that secular effects derived from
gas fraction and gas mass may be the primary causes of asymmetry
in low-mass galaxies. High gas fraction is linked to high σ _m/V
(where σm is Hα velocity dispersion and V the rotation
velocity), which is strongly correlated with \overline{v_asym},
and galaxies with log (M*/M⊙) < 9.0 have
offset \overline{σ _m/V} from the rest of the sample. Further,
asymmetry as a fraction of dispersion decreases for galaxies with log
(M*/M⊙) < 9.0. Gas mass and asymmetry are
also inversely correlated in our sample. We propose that low gas masses
in dwarf galaxies may lead to asymmetric distribution of gas clouds,
leading to increased relative turbulence.
Title: The SAMI Galaxy Survey: the low-redshift stellar mass
Tully-Fisher relation
Authors: Bloom, J. V.; Croom, S. M.; Bryant, J. J.; Callingham,
J. R.; Schaefer, A. L.; Cortese, L.; Hopkins, A. M.; D'Eugenio, F.;
Scott, N.; Glazebrook, K.; Tonini, C.; McElroy, R. E.; Clark, H. A.;
Catinella, B.; Allen, J. T.; Bland-Hawthorn, J.; Goodwin, M.; Green,
A. W.; Konstantopoulos, I. S.; Lawrence, J.; Lorente, N.; Medling,
A. M.; Owers, M. S.; Richards, S. N.; Sharp, R.
Bibcode: 2017MNRAS.472.1809B
Altcode: 2017arXiv171110726B
We investigate the Tully-Fisher relation (TFR) for a morphologically
and kinematically diverse sample of galaxies from the Sydney-AAO
Multi-object Integral field spectrograph (SAMI) Galaxy Survey using
two-dimensional spatially resolved H α velocity maps and find a
well-defined relation across the stellar mass range of 8.0 < log
(M*/M⊙) < 11.5. We use an adaptation of
kinemetry to parametrize the kinematic H α asymmetry of all galaxies
in the sample, and find a correlation between scatter (i.e. residuals
off the TFR) and asymmetry. This effect is pronounced at low stellar
mass, corresponding to the inverse relationship between stellar
mass and kinematic asymmetry found in previous work. For galaxies
with log (M*/M⊙) < 9.5, 25 ± 3 per cent
are scattered below the root mean square (RMS) of the TFR, whereas
for galaxies with log (M*/M⊙) > 9.5 the
fraction is 10 ± 1 per cent. We use 'simulated slits' to directly
compare our results with those from long slit spectroscopy and find
that aligning slits with the photometric, rather than the kinematic,
position angle, increases global scatter below the TFR. Further,
kinematic asymmetry is correlated with misalignment between the
photometric and kinematic position angles. This work demonstrates the
value of 2D spatially resolved kinematics for accurate TFR studies;
integral field spectroscopy reduces the underestimation of rotation
velocity that can occur from slit positioning off the kinematic axis.
Title: What's Cooler Than Being Cool? Icefin: Robotic Exploration
Beneath Antarctic Ice Shelves
Authors: Lawrence, J.; Schmidt, B. E.; Meister, M. R.; Glass, J. B.;
Bowman, J. S.; Stockton, A. M.; Dichek, D.; Hurwitz, B.; Ramey, C.;
Spears, A.; Walker, C. C.
Bibcode: 2017AGUFM.P43C2902L
Altcode:
The 2017-18 Antarctic field season marks the first of three under
the RISEUP project (Ross Ice Shelf & Europa Underwater Probe,
NASA PSTAR program grant NNX16AL07G, PI B. E. Schmidt). RISEUP
expands our efforts to understand the physical processes governing
ice-ocean interactions from beneath the McMurdo Ice Shelf (MIS)
to the Ross Ice Shelf (RIS), utilizing the modular autonomous or
remotely operable submersible vehicle (AUV/ROV) Icefin. The remote,
aphotic regions below Antarctic shelves present a unique opportunity-
they are both poorly understood terrestrial environments and analogs
for similar systems hypothesized to be present on other bodies in
our solar system, such as Europa and Enceladus. By developing new
robotic technologies to access and explore ice shelf cavities we are
advancing our understanding of how temperature, pressure, and salinity
influence the ice-ocean interface, the limits of habitable environments
on Earth, and what biological processes and adaptations enable the life
discovered by the RISP and WISSARD programs during initial exploration
beneath the RIS. These investigations further our understanding of
ocean world habitability and support planned and proposed planetary
missions (e.g. Europa Clipper, Europa Lander) via improved constraint
of marine ice accretion processes, organic entrainment, and interface
habitability. Custom built at Georgia Tech and first deployed during
the 2014/15 Antarctic season, Icefin is 3.5 m, 125 kg modular vehicle
that now carries a full suite of oceanographic sensors (including
conductivity, temperature, depth, dissolved O2, dissolved organic
matter, turbidity, pH, eH, and sonar) that can be deployed through
boreholes as small as 25 cm in diameter. Here we present continued
analysis of basal ice and oceanographic observations in the McMurdo
Sound region from 2012-2015 with, pending anticipated field work,
comparisons to preliminary data from the 2017/18 field season beneath
both the McMurdo and Ross Ice Shelves.
Title: The SAMI Galaxy Survey: the intrinsic shape of kinematically
selected galaxies
Authors: Foster, C.; van de Sande, J.; D'Eugenio, F.; Cortese,
L.; McDermid, R. M.; Bland-Hawthorn, J.; Brough, S.; Bryant, J.;
Croom, S. M.; Goodwin, M.; Konstantopoulos, I. S.; Lawrence, J.;
López-Sánchez, Á. R.; Medling, A. M.; Owers, M. S.; Richards,
S. N.; Scott, N.; Taranu, D. S.; Tonini, C.; Zafar, T.
Bibcode: 2017MNRAS.472..966F
Altcode: 2017arXiv170903585F
Using the stellar kinematic maps and ancillary imaging data from the
Sydney AAO Multi Integral field (SAMI) Galaxy Survey, the intrinsic
shape of kinematically selected samples of galaxies is inferred. We
implement an efficient and optimized algorithm to fit the intrinsic
shape of galaxies using an established method to simultaneously
invert the distributions of apparent ellipticities and kinematic
misalignments. The algorithm output compares favourably with previous
studies of the intrinsic shape of galaxies based on imaging alone and
our re-analysis of the ATLAS3D data. Our results indicate
that most galaxies are oblate axisymmetric. We show empirically
that the intrinsic shape of galaxies varies as a function of their
rotational support as measured by the 'spin' parameter proxy λ
_{R_e}. In particular, low-spin systems have a higher occurrence of
triaxiality, while high-spin systems are more intrinsically flattened
and axisymmetric. The intrinsic shape of galaxies is linked to
their formation and merger histories. Galaxies with high-spin values
have intrinsic shapes consistent with dissipational minor mergers,
while the intrinsic shape of low-spin systems is consistent with
dissipationless multimerger assembly histories. This range in assembly
histories inferred from intrinsic shapes is broadly consistent with
expectations from cosmological simulations.
Title: Using an artificial neural network to classify multicomponent
emission lines with integral field spectroscopy from SAMI and S7
Authors: Hampton, E. J.; Medling, A. M.; Groves, B.; Kewley, L.;
Dopita, M.; Davies, R.; Ho, I. -T.; Kaasinen, M.; Leslie, S.;
Sharp, R.; Sweet, S. M.; Thomas, A. D.; Allen, J.; Bland-Hawthorn,
J.; Brough, S.; Bryant, J. J.; Croom, S.; Goodwin, M.; Green, A.;
Konstantantopoulos, I. S.; Lawrence, J.; López-Sánchez, Á. R.;
Lorente, N. P. F.; McElroy, R.; Owers, M. S.; Richards, S. N.;
Shastri, P.
Bibcode: 2017MNRAS.470.3395H
Altcode: 2016arXiv160608133H
Integral field spectroscopy (IFS) surveys are changing how we study
galaxies and are creating vastly more spectroscopic data available
than before. The large number of resulting spectra makes visual
inspection of emission line fits an infeasible option. Here, we
present a demonstration of an artificial neural network (ANN) that
determines the number of Gaussian components needed to describe the
complex emission line velocity structures observed in galaxies after
being fit with lzifu. We apply our ANN to IFS data for the S7 survey,
conducted using the Wide Field Spectrograph on the ANU 2.3 m Telescope,
and the SAMI Galaxy Survey, conducted using the SAMI instrument on the
4 m Anglo-Australian Telescope. We use the spectral fitting code lzifu
(Ho et al. 2016a) to fit the emission line spectra of individual spaxels
from S7 and SAMI data cubes with 1-, 2- and 3-Gaussian components. We
demonstrate that using an ANN is comparable to astronomers performing
the same visual inspection task of determining the best number of
Gaussian components to describe the physical processes in galaxies. The
advantage of our ANN is that it is capable of processing the spectra
for thousands of galaxies in minutes, as compared to the years this
task would take individual astronomers to complete by visual inspection.
Title: Comparison of the Scaling Properties of EUV Intensity
Fluctuations in Coronal Holes to those in Regions of Quiet Sun
Authors: Cadavid, Ana Cristina; Lawrence, John K.; Jennings, Peter John
Bibcode: 2017SPD....4810613C
Altcode:
We investigate the scaling properties of EUV intensity fluctuations
seen in low-latitude coronal holes (CH) and in regions of Quiet Sun
(QS), in signals obtained with the SDO/AIA instrument in the 193 Å
waveband. Contemporaneous time series in the 171 and 211 Å wavebands
are used for comparison among emissions at different heights in the
transition region and low corona. Potential-field extrapolations
of contemporaneous SDO/HMI line-of-sight magnetic fields provide a
context in the physical environment. Detrended fluctuation analysis
(DFA) shows that the variance of the fluctuations obeys a power-law
as a function of temporal scales with periods in the range ~15-60
min. This scaling is characterized by a generalized Hurst exponent
α. In QS regions, and in regions within CHs that include magnetic
bipoles, the scaling exponent lies in the range 1.0 < α < 1.5,
and it thus corresponds to anti-correlated, turbulent-like, dynamical
processes. Regions inside the coronal holes primarily associated
with magnetic field of a dominant single polarity, have a generalized
exponent (0.5 < α < 1) corresponding to positively correlated
(“persistent”) processes. The results indicate the influence of
the magnetic fields on the dynamics of the emission.
Title: Demonstration of an efficient, photonic-based astronomical
spectrograph on an 8-m telescope
Authors: Jovanovic, N.; Cvetojevic, N.; Norris, B.; Betters, C.;
Schwab, C.; Lozi, J.; Guyon, O.; Gross, S.; Martinache, F.; Tuthill,
P.; Doughty, D.; Minowa, Y.; Takato, N.; Lawrence, J.
Bibcode: 2017OExpr..2517753J
Altcode: 2017arXiv170701847J
We demonstrate for the first time an efficient, photonic-based
astronomical spectrograph on the 8-m Subaru Telescope. An extreme
adaptive optics system is combined with pupil apodiziation optics
to efficiently inject light directly into a single-mode fiber,
which feeds a compact cross-dispersed spectrograph based on array
waveguide grating technology. The instrument currently offers a
throughput of 5% from sky-to-detector which we outline could easily be
upgraded to ~13% (assuming a coupling efficiency of 50%). The isolated
spectrograph throughput from the single-mode fiber to detector was 42%
at 1550 nm. The coupling efficiency into the single-mode fiber was
limited by the achievable Strehl ratio on a given night. A coupling
efficiency of 47% has been achieved with ~60% Strehl ratio on-sky
to date. Improvements to the adaptive optics system will enable
90% Strehl ratio and a coupling of up to 67% eventually. This work
demonstrates that the unique combination of advanced technologies
enables the realization of a compact and highly efficient spectrograph,
setting a precedent for future instrument design on very-large and
extremely-large telescopes.
Title: Insights Into Ice-Ocean Interactions on Earth and Europa
Authors: Lawrence, J.; Schmidt, B. E.; Winslow, L.; Doran, P. T.;
Kim, S.; Walker, C. C.; Buffo, J.; Skidmore, M. L.; Soderlund, K. M.;
Blankenship, D. D.; Bramall, N. E.; Johnson, A.; Rack, F. R.; Stone,
W.; Kimball, P.; Clark, E.
Bibcode: 2016AGUFM.P31A2077L
Altcode:
Europa and Earth appear to be drastically different worlds, yet below
their icy crusts the two likely share similar oceanic conditions
including temperatures, pressures (relatively), and salinity. Earth's
ice shelves provide an important analog for the physiochemical,
and potentially microbial, characteristics of icy worlds. NASA's
ASTEP program funded Sub-Ice Marine and PLanetary-analog Ecosystems
(SIMPLE) to help address the fundamental processes occurring at ice
ocean interfaces, the extent and limitations of life in sub-ice
environments, and how environmental properties and biological
communities interact. The relationships between currents, temperature,
and salinity with physical processes such as melt, freeze, and
marine ice accretion at the basal surfaces of ice shelves influence
habitability yet are poorly understood even on Earth. Resultant
processes such as the inclusion of ocean-derived material in ice
shelves and the transport of biotics from the interface towards the
surface via ablation, convection, and diapirism also have important
astrobiological implications for Europa.Here, we present results
from CTD and imaging data gathered at multiple locations beneath the
McMurdo Ice Shelf (MIS) to highlight how the ice and ocean interact
in a Europan analog environment. Over the course of three years,
the SIMPLE team observed heterogeneity in the water column and basal
ice beneath the MIS. During the recent 2015 field season we deployed
ARTEMIS, an AUV capable of characterizing the interface over multiple
kilometer missions, and conducted daily CTD casts to 480 m (bottom
depth 529 m) in November adjacent to the terminus of the MIS to capture
temporal variation in the water column. These casts show the presence
of transient water masses related to the tidal period, each containing
a single or double temperature minimum (down to -1.97 °C from -1.93
°C) between 60 to 150 m depth. Further comparisons between years
and sampling locations demonstrate the homogeneity of the subshelf
environment even on the scale of tens of kilometers. The technologies
supported by SIMPLE are also supporting the ice penetrating radar on
the upcoming Europa Flagship mission, and will hopefully inform future
ocean world exploration.
Title: Multi-scaling Properties of EUV Intensity Fluctuations and
Models for Impulsive Heating
Authors: Cadavid, A. C.; Rivera, Y.; Lawrence, J. K.; Christian,
D. J.; Jennings, P.; Rappazzo, A. F.
Bibcode: 2016AGUFMSH42B..05C
Altcode:
There is wide agreement on the importance of impulsive processes
("nanoflares") to explain coronal heating. Diagnostics of observational
data are necessary to uncover signatures of the underlying mechanisms,
and, by comparing to those of simulated data, to determine whether a
model explains the observations. We have investigated the multi-scaling
properties that characterize the intermittency of AIA/SDO radiance
fluctuations. Lags between pairs of wavebands were used to distinguish
coronal from transition region (TR) signals. Noise degrades the signals,
so the 171Å emission, with the highest signal-to-noise ratio, provides
the best information. In an active region core, for both loops and
for diffuse emission, the probability distribution functions (PDFs) of
the increments of both TR and coronal signals are "quasi-Gaussian" for
large temporal scales and "leptokurtic" (peaked with heavy tails) for
small time increments, as expected for turbulent systems. Multifractal
Detrended Fluctuation Analysis (MF-DFA) shows that the variance of
the fluctuations obeys a power law as a function of temporal scales in
the range 15-45 min. The value of the scaling exponent indicates that,
on average, the time series are nonstationary and anti-persistent with
small fluctuations following large fluctuations and vice versa. Other
moments of the fluctuations obey corresponding power laws and the
multi-scaling exponents quantify the degree of the intermittency in
the context of multifractality. The variation in the scaling exponents
results from long term correlation in the time series. The multiscaling
of the EUV data agrees qualitatively with simulated intensity from a
simple model of impulsive bursts plus noise, and also with the ohmic
dissipation in a Reduced Magnetohydrodynamic (RMHD) model for coronal
loop heating. However, the observational data were found to disagree
with the modeled PDFs of increments. There is indication that the
multifractal properties in the observations could be related to a
modified multiplicative cascade model characterized by two parameters.
Title: Multifractal Solar EUV Intensity Fluctuations and their
Implications for Coronal Heating Models
Authors: Cadavid, A. C.; Rivera, Y. J.; Lawrence, J. K.; Christian,
D. J.; Jennings, P. J.; Rappazzo, A. F.
Bibcode: 2016ApJ...831..186C
Altcode: 2016arXiv160902625C
We investigate the scaling properties of the long-range temporal
evolution and intermittency of Atmospheric Imaging Assembly/Solar
Dynamics Observatory intensity observations in four solar environments:
an active region core, a weak emission region, and two core loops. We
use two approaches: the probability distribution function (PDF) of
time series increments and multifractal detrended fluctuation analysis
(MF-DFA). Noise taints the results, so we focus on the 171 Å waveband,
which has the highest signal-to-noise ratio. The lags between pairs of
wavebands distinguish between coronal versus transition region (TR)
emission. In all physical regions studied, scaling in the range of
15-45 minutes is multifractal, and the time series are anti-persistent
on average. The degree of anti-correlation in the TR time series is
greater than that for coronal emission. The multifractality stems from
long-term correlations in the data rather than the wide distribution
of intensities. Observations in the 335 Å waveband can be described
in terms of a multifractal with added noise. The multiscaling of the
extreme-ultraviolet data agrees qualitatively with the radiance from
a phenomenological model of impulsive bursts plus noise, and also
from ohmic dissipation in a reduced magnetohydrodynamic model for
coronal loop heating. The parameter space must be further explored to
seek quantitative agreement. Thus, the observational “signatures”
obtained by the combined tests of the PDF of increments and the MF-DFA
offer strong constraints that can systematically discriminate among
models for coronal heating.
Title: Instrumentation progress at the Giant Magellan Telescope
project
Authors: Jacoby, George H.; Bernstein, R.; Bouchez, A.; Colless,
M.; Crane, Jeff; DePoy, D.; Espeland, B.; Hare, Tyson; Jaffe, D.;
Lawrence, J.; Marshall, J.; McGregor, P.; Shectman, Stephen; Sharp,
R.; Szentgyorgyi, A.; Uomoto, Alan; Walls, B.
Bibcode: 2016SPIE.9908E..1UJ
Altcode:
Instrument development for the 24m Giant Magellan Telescope
(GMT) is described: current activities, progress, status, and
schedule. One instrument team has completed its preliminary design
and is currently beginning its final design (GCLEF, an optical
350-950 nm, high-resolution and precision radial velocity echelle
spectrograph). A second instrument team is in its conceptual design
phase (GMACS, an optical 350-950 nm, medium resolution, 6-10 arcmin
field, multi-object spectrograph). A third instrument team is
midway through its preliminary design phase (GMTIFS, a near-IR YJHK
diffraction-limited imager/integral-field-spectrograph), focused on
risk reduction prototyping and design optimization. A fourth instrument
team is currently fabricating the 5 silicon immersion gratings needed
to begin its preliminary design phase (GMTNIRS, a simultaneous JHKLM
high-resolution, AO-fed, echelle spectrograph). And, another instrument
team is focusing on technical development and prototyping (MANIFEST, a
facility robotic, multifiber feed, with a 20 arcmin field of view). In
addition, a medium-field (6 arcmin, 0.06 arcsec/pix) optical imager
will support telescope and AO commissioning activities, and will excel
at narrow-band imaging. In the spirit of advancing synergies with
other groups, the challenges of running an ELT instrument program and
opportunities for cross-ELT collaborations are discussed.
Title: Ground Ice on Ceres?
Authors: Schmidt, B. E.; Hughson, K. G.; Chilton, H. T.; Scully,
J. E. C.; Platz, T.; Nathues, A.; Sizemore, H.; Bland, M. T.; Byrne,
S.; Marchi, S.; O'Brien, D. P.; Schorghofer, N.; Hiesinger, H.;
Jaumann, R.; Lawrence, J.; Buczkowski, D.; Castillo, J. C.; Schenk,
P. M.; Sykes, M. V.; De Sanctis, M. C.; Mitri, G.; Formisano, M.;
Li, J. -Y.; Reddy, V.; LeCorre, L.; Russell, C. T.; Raymond, C. A.;
Dawn Science; Operations Team
Bibcode: 2016LPI....47.2677S
Altcode:
We present geomorphological evidence that suggests ice is an important
component of near surface material on Ceres.
Title: Writing Bragg Gratings in Multicore Fibers
Authors: Lindley, E. Y.; Min, S. S.; Leon-Saval, S. G.; Cvetojevic,
N.; Lawrence, J.; Ellis, S. C.; Bland-Hawthorn, J.
Bibcode: 2016JOVE..11053326L
Altcode:
No abstract at ADS
Title: Scaling and Long Term Correlation Properties of EUV Intensity
Fluctuations and Implications for Impulsive Heating Mechanisms of
the Solar Corona
Authors: Rivera, Y.; Cadavid, A. C.; Lawrence, J. K.
Bibcode: 2015AGUFMSH13B2445R
Altcode:
Scaling properties of the stochastic component of EUV intensity
fluctuations from AIA/SDO observations show long-term correlations
and can carry information about the energetics of coronal loops. Power
spectra indicate that the stochastic time series are nonstationary. Thus
we apply the method of detrended fluctuation analysis (DFA), which
was designed to determine the true scaling properties of a signal. It
can identify the long-term correlations in noisy and nonstationary
time series after accounting for external influences. The scaling
exponents encountered in the solar fluctuation functions indicate
long-time correlations of the series. We study to what degree the
properties may correspond to those of fractional Brownian motion
(fBm) or fractional Gaussian noise (fGn) processes. Analysis of a
non-flaring active region (AR) indicates that the EUV emission in
the hot 131 Å (Fe XXI), hot 94 Å (Fe XVIII) and 335 Å intensity
bands has different properties from the warm emission in the 211, 193
and 171 Å bands. Further differences are found in the quiet vs AR
core regions. The intensity values satisfy probability distribution
functions (pdf)s corresponding to superposed lognormal and Gaussian
functions. The pdfs of the increments are Gaussian. The properties of
the data can be reproduced by a physically motivated phenomenological
model for impulsive heating with added noise. We propose that DFA,
complemented with the identification of the pdfs, can be a useful tool
to constrain more realistic models of coronal heating.
Title: Correlation and scaling properties of non-stationary
intensity fluctuations in coronal EUVtime series in different
physical environments
Authors: Cadavid, Ana Cristina; Lawrence, John; Rivera, Yeimy
Bibcode: 2015TESS....120307C
Altcode:
Previously we have used EUV observations from AIA/SDO to examine
properties of energy deposition into coronal-loops in non-flaring
active region (AR) cores. The evolution of the loop apex intensity,
temperature, and electron density indicate that the loops are
impulsively heated in a mode compatible with high intensity nanoflare
storms characterized by a progressive cooling pattern in the EUV lines
with the hot channels leading the emission. Spectra of the hot 131
Å intensity (basically Fe XXI) and of the energy dissipation in a 2D
model of loop magneto-turbulence compatible with nanoflare statistics,
both exhibit three scaling regimes with low frequencies corresponding
to 1/f noise, the intermediate range indicating a persistent process,
and high frequencies corresponding to white noise. The varying power
law behavior in these spectra indicates that both the observational
and the simulated time series are not stationary. Therefore to
extend the analysis beyond the AR loops we apply the method of
detrended fluctuation analysis (DFA) that was developed to study
the long-range correlations in non-stationary signals. DFA provides
a scaling exponent that characterizes the correlation properties of
the signal and which can be related both to the spectral exponents
and to the Hurst exponent. In areas of diffuse emission and for all
the spectral channels the time series of intensity fluctuations are
characterized by scaling exponents that indicate a weak positive
correlation across all time scales. In regions with intermittent
intensity brightenings a cross-over occurs at timescales near 10 -
20 min with different exponents describing the degree of positive
correlation of the intensity fluctuations at short and long time
scales. Qualitative differences exist between the exponents of the
hotter and the cooler channels. We have further compared the scaling
properties of the time series associated with different physical
environments distinguished by the possibility of underlying nanoflare
storms, or by the strength of the magnetic field in contemporaneous
HMI images. Another comparison is made to the scaling properties of
simulations of energy dissipation in magnetoturbulence.
Title: Heating Mechanisms for Intermittent Loops in Active Region
Cores from AIA/SDO EUV Observations
Authors: Cadavid, A. C.; Lawrence, J. K.; Christian, D. J.; Jess,
D. B.; Nigro, G.
Bibcode: 2014ApJ...795...48C
Altcode: 2014arXiv1404.7824C
We investigate intensity variations and energy deposition in five
coronal loops in active region cores. These were selected for their
strong variability in the AIA/SDO 94 Å intensity channel. We
isolate the hot Fe XVIII and Fe XXI components of the 94 Å and
131 Å by modeling and subtracting the "warm" contributions to the
emission. HMI/SDO data allow us to focus on "inter-moss" regions
in the loops. The detailed evolution of the inter-moss intensity
time series reveals loops that are impulsively heated in a mode
compatible with a nanoflare storm, with a spike in the hot 131 Å
signals leading and the other five EUV emission channels following in
progressive cooling order. A sharp increase in electron temperature
tends to follow closely after the hot 131 Å signal confirming the
impulsive nature of the process. A cooler process of growing emission
measure follows more slowly. The Fourier power spectra of the hot
131 Å signals, when averaged over the five loops, present three
scaling regimes with break frequencies near 0.1 min-1
and 0.7 min-1. The low frequency regime corresponds to
1/f noise; the intermediate indicates a persistent scaling process
and the high frequencies show white noise. Very similar results are
found for the energy dissipation in a 2D "hybrid" shell model of loop
magneto-turbulence, based on reduced magnetohydrodynamics, that is
compatible with nanoflare statistics. We suggest that such turbulent
dissipation is the energy source for our loops.
Title: Status of the instrumentation program for the Giant Magellan
Telescope
Authors: Jacoby, George H.; Bouchez, A.; Colless, M.; DePoy, D.;
Jaffe, D.; Lawrence, J.; McGregor, P.; Bernstein, R.; Shectman, S.;
Szentgyorgyi, A.
Bibcode: 2014SPIE.9147E..1YJ
Altcode:
Instrument development for the 25 m class optical/infrared Giant
Magellan Telescope (GMT) is actively underway. Two instruments
have begun their preliminary design phase: an optical (350-1000
nm) high resolution and precision radial velocity echelle
spectrograph (G-CLEF), and a near-IR (YJHK) diffraction-limited
imager/integral-field-spectrograph (GMTIFS). A third instrument
will begin its design phase in early 2015: an optical (370-1000 nm)
low-to-medium resolution multi-object spectrograph (GMACS). Two
other instrument teams are focusing on prototypes to demonstrate
final feasibility: a near-to-mid-IR (JHKLM) high resolution
diffraction-limited echelle (GMTNIRS) spectrograph, and a facility
robotic multi-fiber-feed (MANIFEST). A brief overview of the
GMT instrumentation program is presented: current activities,
progress, status, and schedule, as well as a summary of the facility
infrastructure needed to support the instruments.
Title: Enhancing performance of metre-class telescopes by using
photonic devices
Authors: Spaleniak, I.; Jovanovic, N.; Ireland, M.; Gross, S.;
Lawrence, J.; Withford, M.
Bibcode: 2014CoSka..43..228S
Altcode:
Over the last couple of years there has been increased interest
in single-mode spectrographs, such as bulk optics-based single
mode spectrographs and integrated photonic spectrographs. Such
instruments have several key advantages over traditional (multi-moded)
spectrographs: precision, small size, and related relatively low
cost. However, the ground-based telescopes suffer from atmospheric
distortions causing the light delivered by astronomical telescopes being
multi-mode (seeing-limited) in nature. Current solutions to correct
for atmospheric turbulence (such as adaptive optics) are inefficient
in the visible wavelength range and very expensive. Therefore, we use
an alternative solution and develop devices called photonic lanterns
which convert a seeing-limited signal into multiple diffraction-limited
spots and suit as a link between the telescope and a single-mode
device. By means of the ultrafast laser inscription, we fabricate
photonic lanterns on a glass chip. We optimised the design in order to
achieve high throughput and created robust, highly efficient devices,
which can greatly enhance the efficiency and performance of the
seeing-limited telescopes.
Title: Different Periodicities in the Sunspot Area and the Occurrence
of Solar Flares and Coronal Mass Ejections in Solar Cycle 23 - 24
Authors: Choudhary, D. P.; Lawrence, J. K.; Norris, M.; Cadavid, A. C.
Bibcode: 2014SoPh..289..649C
Altcode:
In order to investigate the relationship between magnetic-flux
emergence, solar flares, and coronal mass ejections (CMEs), we study
the periodicity in the time series of these quantities. It has been
known that solar flares, sunspot area, and photospheric magnetic flux
have a dominant periodicity of about 155 days, which is confined to
a part of the phase of the solar cycle. These periodicities occur at
different phases of the solar cycle during successive phases. We present
a time-series analysis of sunspot area, flare and CME occurrence during
Cycle 23 and the rising phase of Cycle 24 from 1996 to 2011. We find
that the flux emergence, represented by sunspot area, has multiple
periodicities. Flares and CMEs, however, do not occur with the same
period as the flux emergence. Using the results of this study, we
discuss the possible activity sources producing emerging flux.
Title: Non-steady, Intermittent, Hot Loops in an Active Region
Observed with the SDO/AIA
Authors: Cadavid, Ana C.; Lawrence, J. K.; Christian, D. J.
Bibcode: 2013SPD....44...48C
Altcode:
While there is accumulated evidence of high temperature coronal emission
in active region cores that corresponds to structures in equilibrium,
other studies have found of evolving loops. We investigate the EUV
intensity variations of two low and short coronal loops observed
in the core of NOAA AR 11250 on 13 July 2011 between UT 12:02
and 16:32. The loops (32 Mm loop 1, 23 Mm loop 2), run directly
between the AR opposite polarities, and are first detectable in
the 94Å band (effective temperature ~ 7 MK). Space-time slices
present intermittent brightenings evocative of turbulence. Spatial
averages over the intermoss loop region lead to light curves used to
analyze the temporal evolution of the loops. We find quantities with
scaling regimes that are characteristic of intermittent processes. In
particular intensity histograms display scaling ranges with slopes ~
-1.8, and spectra also show a scaling region for frequencies 1-8 mHz,
with slopes - 3.8 (loop 1) and -2.8 (loop 2). We further investigate
the time evolution of the loops in five other AIA EUV channels. The
results are separated into two classes. Group A (94Å, 335Å, 211Å)
characterized by hotter temperatures 2-6 MK), and group B (193Å, 171Å,
131Å) by cooler temperatures (0.4 - 1.6 MK). In loop 1 (group A) the
intensity peaks in the 94Å channel are followed by maxima in the 335
Å channel with a time lag of ~10 min, suggestive of a cooling pattern
with an exponential decay. The 211Å maxima follow those in the 335
Å channel, but there is no systematic relation which would indicate
a progressive cooling process. In group B the signals in the 171 and
131Å channels track each other closely, and tend to lag behind the
193Å. The three signals follow a general gradual increase reaching a
maximum at about the middle of the time series and then decrease. An
exponential cooling model can also be associated with the 193 and 171Å
pair. For loop 2 the observations in the group B light curves present
similar properties as in loop 1. In contrast the intensity curves
in group A only show one distinct case which could be a candidate
for exponential decay via a 94 Å to 335 Å cooling process.Abstract
(2,250 Maximum Characters): While there is accumulated evidence of high
temperature coronal emission in active region cores that corresponds
to structures in equilibrium, other studies have found of evolving
loops. We investigate the EUV intensity variations of two low and short
coronal loops observed in the core of NOAA AR 11250 on 13 July 2011
between UT 12:02 and 16:32. The loops (32 Mm loop 1, 23 Mm loop 2), run
directly between the AR opposite polarities, and are first detectable
in the 94Å band (effective temperature ~ 7 MK). Space-time slices
present intermittent brightenings evocative of turbulence. Spatial
averages over the intermoss loop region lead to light curves used to
analyze the temporal evolution of the loops. We find quantities with
scaling regimes that are characteristic of intermittent processes. In
particular intensity histograms display scaling ranges with slopes ~
-1.8, and spectra also show a scaling region for frequencies 1-8 mHz,
with slopes - 3.8 (loop 1) and -2.8 (loop 2). We further investigate
the time evolution of the loops in five other AIA EUV channels. The
results are separated into two classes. Group A (94Å, 335Å, 211Å)
characterized by hotter temperatures 2-6 MK), and group B (193Å, 171Å,
131Å) by cooler temperatures (0.4 - 1.6 MK). In loop 1 (group A) the
intensity peaks in the 94Å channel are followed by maxima in the 335
Å channel with a time lag of ~10 min, suggestive of a cooling pattern
with an exponential decay. The 211Å maxima follow those in the 335
Å channel, but there is no systematic relation which would indicate
a progressive cooling process. In group B the signals in the 171 and
131Å channels track each other closely, and tend to lag behind the
193Å. The three signals follow a general gradual increase reaching a
maximum at about the middle of the time series and then decrease. An
exponential cooling model can also be associated with the 193 and 171Å
pair. For loop 2 the observations in the group B light curves present
similar properties as in loop 1. In contrast the intensity curves in
group A only show one distinct case which could be a candidate for
exponential decay via a 94 Å to 335 Å cooling process.
Title: Plasma-driven Z-pinch X-ray loading and momentum coupling in
meteorite and planetary materials
Authors: Remo, John L.; Furnish, Michael D.; Lawrence, R. Jeffery;
Lawrence
Bibcode: 2013JPlPh..79..121R
Altcode:
X-ray momentum coupling coefficients, C M, were determined
by measuring stress waveforms in planetary materials subjected to
impulsive radiation loading from the Sandia National Laboratories
Z-machine. Velocity interferometry (VISAR) diagnostics provided
equation-of-state data. Targets were iron and stone meteorites,
magnesium-rich olivine (dunite) solid and powder (~5-300 μm), and Si,
Al, and Fe calibration targets. Samples were ~1-mm thick and, except
for Si, backed by LiF single-crystal windows. X-ray spectra combined
thermal radiation (blackbody 170-237 eV) and line emissions from pinch
materials (Cu, Ni, Al, or stainless steel). Target fluences of 0.4-1.7
kJ/cm2 at intensities of 43-260GW/cm2 produced
plasma pressures of 2.6-12.4 GPa. The short (~5 ns) drive pulses gave
rise to attenuating stress waves in the samples. The attenuating wave
impulse is constant, allowing accurate C M measurements from
rear-surface motion. C M was 1.9 - 3.1 × 10-5
s/m for stony meteorites, 2.7 and 0.5 × 10-5 s/m for
solid and powdered dunite, 0.8 - 1.4 × 10-5 s/m for iron
meteorites, and 0.3, 1.8, and 2.7 × 10-5 s/m respectively
for Si, Fe, and Al calibration targets. Results are consistent
with geometric scaling from recent laser hohlraum measurements. CTH
hydrocode modeling of X-ray coupling to porous silica corroborated
experimental measurements and supported extrapolations to other
materials. CTH-modeled C M for porous materials was low
and consistent with experimental results. Analytic modeling (BBAY)
of X-ray radiation-induced momentum coupling to selected materials
was also performed, often producing higher C M values than
experimental results. Reasons for the higher values include neglect
of solid ejecta mechanisms, turbulent mixing of heterogeneous phases,
variances in heats of melt/vaporization, sample inhomogeneities, wave
interactions at the sample/window boundary, and finite sample/window
sizes. The measurements validate application of C M to
(inhomogeneous) planetary materials from high-intensity soft X-ray
radiation.
Title: Coupled Effects of a Perturbation in a Complex Structure
Observed with SDO/AIA, SDO/HMI and ROSA/HARDcam
Authors: Cadavid, A. C.; Lawrence, J. K.; Christian, D. J.; Jess,
D. B.; Mathioudakis, M.
Bibcode: 2012AGUFMSH51A2197C
Altcode:
We study properties of intensity fluctuations in NOAA Active Region
11250 observed on 13 July 2011 starting at UT 13:32. Included are
data obtained in the EUV bands of the Atmospheric Imaging Assembly
on board the Solar Dynamics Observatory (SDO/AIA) as well as nearly
simultaneous observations of the chromosphere made, at much higher
spatial and temporal resolution, with the Rapid Oscillations in the
Solar Atmosphere (ROSA) and Hydrogen-Alpha Rapid Dynamics camera
(HARDcam) systems at the Dunn Solar Telescope. A complex structure
seen in both the ROSA/HARDcam and SDO data sets comprises a system of
loops extending outward from near the boundary of the leading sunspot
umbra. It is visible in the ROSA Ca II K and HARDcam Hα images, as
well as the SDO 304 Å, 171 Å and 193 Å channels, and it thus couples
the chromosphere, transition region and corona. In the ground-based
images the loop structure is 4.1 Mm long. Some 17.5 Mm, can be traced
in the SDO/AIA data. The chromospheric emissions observed by ROSA and
HARDcam appear to occupy the inner, and apparently cooler and lower,
quarter of the loop. We compare the intensity fluctuations of two points
within the structure. From alignment with SDO/HMI images we identify a
point "A" near the loop structure, which sits directly above a bipolar
magnetic feature in the photosphere. Point "B" is characteristic of
locations within the loops that are visible in both the ROSA/HARDcam
and the SDO/AIA data. The intensity traces for point A are quiet
during the first part of the data string. At time ~ 19 min they
suddenly begin a series of impulsive brightenings. In the 171 Å and
193 Å coronal lines the brightenings are localized impulses in time,
but in the transition region line at 304 Å they are more extended
in time. The intensity traces in the 304 Å line for point B shows
a quasi-periodic signal that changes properties at about 19 min. The
wavelet power spectra are characterized by two periodicities. A 6.7 min
period extends from the beginning of the series until about 25 minutes,
and another signal with period ~3 min starts at about 20 min. The 193
Å power spectrum has a characteristic period of 5 min, before the
20 min transition and a 2.5 min periodicity afterward. In the case of
HARDcam Hα data a localized 4 min periodicity can be found until about
7 min, followed by a quiet regime. After ~20 min a 2.3 min periodicity
appears. Interestingly a coronal loop visible in the 94 Å line that
is centrally located in the AR, running from the leading umbra to the
following polarity, at about time 20 min undergoes a strong brightening
beginning at the same moment all along 15 Mm of its length. The fact
that these different signals all experience a clear-cut change at time
about 20 min suggests an underlying organizing mechanism. Given that
point A has a direct connection to the photospheric magnetic bipole,
we conjecture that the whole extended structure is connected in a
complex manner to the underlying magnetic field. The periodicities
in these features may favor the wave nature rather than upflows and
interpretations will be discussed.
Title: Coupled Intensity Variations in Hot Coronal Loops Observed
with SDO/AIA
Authors: Lawrence, J. K.; Cadavid, A. C.; Christian, D. J.
Bibcode: 2012AGUFMSH33D2265L
Altcode:
Data from the AIA on board SDO allow us to study EUV intensity
variations of coronal loops. Here we study strong EUV brightenings
of coronal loops in NOAA Active Region 11250 on 13 July 2011 between
UT 13:32 and 14:32. The brightenings are seen only in the 94Å band
of Fe XVIII, implying an effective temperature ~ 8 MK. The relevant
loops run directly between the AR opposite polarities and are low
and short. One example is an apparently single loop north of the
AR midline. At UT 13:50 (18 min into the observational sequence -
see the image) it began a strong brightening in the 94 Å band. This
occurred at the same moment all along 15 Mm of its length to ~ 12 s
accuracy. This suggests the presence of stored free energy along the
loop that was released by an instability that must have propagated
along it at 1500 km/s or faster. The maximum rate of increase of the
94 Å intensity occurred at 20 min into the sequence, and the maximum
was reached at 23 min. It then decayed, reaching its former level
at time 40 min. Another example lay south of the AR midline (see the
image). On its trailing end this loop had two feet, suggesting that
it is a superposition of two loops seen in projection. This structure
showed two strong 94 Å brightenings peaking at 32 min and 37 min
into the data sequence. The first brightening was associated with an
intensity increase in the northern trailing foot, while the second was
associated with an intensity increase in the southern foot. Again,
this points to the presence of two superimposed loops. Brightenings
in the loop feet indicate upward motion of intensity features toward
the loop center at various speeds from 50 - 200 km/s. The intensity
in the central loop section shows a sequence of weaker increases at
4 min intervals preceding the strong brightenings and a still weaker
sequence at 5 min intervals afterward. These indicate releases of
stored energy along a 10 Mm loop segment by a periodically repeating
instability. The onset of the periodic energy releases in Example 2
and also the start of the loop brightening in Example 1 both occur
at time 18 min into the data sequence. This coincides with the time
of disturbances in other features of AR 11250 and suggests a complex
coupling among its various structures.; SDO/AIA images of AR11250 made
in the EUV 94 Å band at UT 13:53 and 14:03 on 13 July 2011. The images
are 94 Mm wide. The grayscale is reversed.
Title: Turbulent Fluctuations in G-band and K-line Intensities
Observed with the Rapid Oscillations in the Solar Atmosphere (ROSA)
Instrument
Authors: Cadavid, A. C.; Lawrence, J. K.; Christian, D. J.; Jess,
D. B.; Mathioudakis, M.
Bibcode: 2012ASPC..463...75C
Altcode:
Using the Rapid Oscillation in the Solar Atmosphere (ROSA) instrument at
the Dunn Solar Telescope we have found that the spectra of fluctuations
of the G-band (cadence 1.05 s) and Ca II K-line (cadence 4.2 s)
intensities show correlated fluctuations above white noise out
to frequencies beyond 300 mHz and up to 70 mHz, respectively. The
noise-corrected G-band spectrum presents a scaling range (Ultra High
Frequency “UHF”) for f = 25-100 mHz, with an exponent consistent
with the presence of turbulent motions. The UHF power, is concentrated
at the locations of magnetic bright points in the intergranular lanes,
it is highly intermittent in time and characterized by a positive
kurtosis κ. Combining values of G-band and K-line intensities, the UHF
power, and κ, reveals two distinct “states” of the internetwork
solar atmosphere. State 1, with κ ≍ 6, which includes almost all
the data, is characterized by low intensities and low UHF power. State
2, with κ ≍ 3, including a very small fraction of the data, is
characterized by high intensities and high UHF power. Superposed epoch
analysis shows that for State 1, the K-line intensity presents 3.5
min chromospheric oscillations with maxima occurring 21 s after G-band
intensity maxima implying a 150-210 km effective height difference. For
State 2, the G-band and K-line intensity maxima are simultaneous,
suggesting that in the highly magnetized environment sites of G-band
and K-line emission may be spatially close together. Analysis of
observations obtained with Hinode/SOT confirm a scaling range in the
G-band spectrum up to 53 mHz also consistent with turbulent motions
as well as the identification of two distinct states in terms of the
H-line intensity and G-band power as functions of G-band intensity.
Title: Observed Effect of Magnetic Fields on the Propagation of
Magnetoacoustic Waves in the Lower Solar Atmosphere
Authors: Lawrence, J. K.; Cadavid, A. C.
Bibcode: 2012SoPh..280..125L
Altcode: 2012SoPh..tmp..159L; 2012arXiv1206.4360L
We study Hinode/SOT-FG observations of intensity fluctuations in Ca II
H-line and G-band image sequences and their relation to simultaneous and
co-spatial magnetic field measurements. We explore the G-band and H-line
intensity oscillation spectra both separately and comparatively via
their relative phase differences, time delays and cross-coherences. In
the non-magnetic situations, both sets of fluctuations show strong
oscillatory power in the 3 - 7 mHz band centered at 4.5 mHz, but
this is suppressed as magnetic field increases. A relative phase
analysis gives a time delay of H-line after G-band of 20±1 s in
non-magnetic situations implying a mean effective height difference of
140 km. The maximum coherence is at 4 - 7 mHz. Under strong magnetic
influence the measured delay time shrinks to 11 s with the peak
coherence near 4 mHz. A second coherence maximum appears between 7.5
- 10 mHz. Investigation of the locations of this doubled-frequency
coherence locates it in diffuse rings outside photospheric magnetic
structures. Some possible interpretations of these results are offered.
Title: Suppression of the near-infrared OH night-sky lines with
fibre Bragg gratings - first results
Authors: Ellis, S. C.; Bland-Hawthorn, J.; Lawrence, J.; Horton,
A. J.; Trinh, C.; Leon-Saval, S. G.; Shortridge, K.; Bryant, J.; Case,
S.; Colless, M.; Couch, W.; Freeman, K.; Gers, L.; Glazebrook, K.;
Haynes, R.; Lee, S.; Löhmannsröben, H. -G.; O'Byrne, J.; Miziarski,
S.; Roth, M.; Schmidt, B.; Tinney, C. G.; Zheng, J.
Bibcode: 2012MNRAS.425.1682E
Altcode: 2012MNRAS.tmp.3549E; 2012arXiv1206.6551E
The background noise between 1 and 1.8 μm in ground-based instruments
is dominated by atmospheric emission from hydroxyl molecules. We have
built and commissioned a new instrument, the Gemini Near-infrared OH
Suppression Integral Field Unit (IFU) System (GNOSIS), which suppresses
103 OH doublets between 1.47 and 1.7 μm by a factor of ≈1000
with a resolving power of ≈10 000. We present the first results
from the commissioning of GNOSIS using the IRIS2 spectrograph at the
Anglo-Australian Telescope. We present measurements of sensitivity,
background and throughput. The combined throughput of the GNOSIS
fore-optics, grating unit and relay optics is ≈36 per cent,
but this could be improved to ≈46 per cent with a more optimal
design. We measure strong suppression of the OH lines, confirming
that OH suppression with fibre Bragg gratings will be a powerful
technology for low-resolution spectroscopy. The integrated OH suppressed
background between 1.5 and 1.7 μm is reduced by a factor of 9 compared
to a control spectrum using the same system without suppression. The
potential of low-resolution OH-suppressed spectroscopy is illustrated
with example observations of Seyfert galaxies and a low-mass star. The GNOSIS background is dominated by detector dark current below
1.67 μm and by thermal emission above 1.67 μm. After subtracting
these, we detect an unidentified residual interline component of
≈860 ± 210 photons s-1 m-2 arcsec-2
μm-1, comparable to previous measurements. This component
is equally bright in the suppressed and control spectra. We have
investigated the possible source of the interline component, but
were unable to discriminate between a possible instrumental artefact
and intrinsic atmospheric emission. Resolving the source of this
emission is crucial for the design of fully optimized OH suppression
spectrographs. The next-generation OH suppression spectrograph
will be focused on resolving the source of the interline component,
taking advantage of better optimization for a fibre Bragg grating
feed incorporating refinements of design based on our findings from
GNOSIS. We quantify the necessary improvements for an optimal OH
suppressing fibre spectrograph design.
Title: The Dark Energy Spectrometer (DESpec): A Multi-Fiber
Spectroscopic Upgrade of the Dark Energy Camera and Survey for the
Blanco Telescope
Authors: Abdalla, F.; Annis, J.; Bacon, D.; Bridle, S.; Castander,
F.; Colless, M.; DePoy, D.; Diehl, H. T.; Eriksen, M.; Flaugher, B.;
Frieman, J.; Gaztanaga, E.; Hogan, C.; Jouvel, S.; Kent, S.; Kirk, D.;
Kron, R.; Kuhlmann, S.; Lahav, O.; Lawrence, J.; Lin, H.; Marriner,
J.; Marshall, J.; Mohr, J.; Nichol, R. C.; Sako, M.; Saunders, W.;
Soares-Santos, M.; Thomas, D.; Wechsler, R.; West, A.; Wu, H.
Bibcode: 2012arXiv1209.2451A
Altcode:
We describe an initiative to build and use the Dark Energy Spectrometer
(DESpec), a wide-field spectroscopic survey instrument for the Blanco
4 meter telescope at Cerro Tololo InterAmerican Observatory (CTIO)
in Chile. A new system with about 4000 robotically positioned optical
fibers will be interchangeable with the CCD imager of the existing Dark
Energy Camera (DECam), accessing a field of view of 3.8 square degrees
in a single exposure. The proposed instrument will be operated by CTIO
and available for use by the astronomy community. Our collaboration
proposes to use DESpec to conduct a wide, deep spectroscopic survey
to study Dark Energy. In a survey of about 350 nights, the DESpec
collaboration proposes to obtain spectroscopic redshifts for about 8
million galaxies over 5000 square degrees selected from the Dark Energy
Survey (DES). This Dark Energy Spectroscopic Survey will advance our
knowledge of cosmic expansion and structure growth significantly beyond
that obtainable with imaging-only surveys. Since it adds a spectroscopic
third dimension to the same sky as DES, DESpec will enable increasingly
precise techniques to discriminate among alternative explanations of
cosmic acceleration, such as Dark Energy and Modified Gravity.
Title: Rapid Fluctuations in the Lower Solar Atmosphere
Authors: Lawrence, J. K.; Cadavid, A. C.; Christian, D. J.; Jess,
D. B.; Mathioudakis, M.
Bibcode: 2011ApJ...743L..24L
Altcode: 2011arXiv1111.4253L
The Rapid Oscillations in the Solar Atmosphere instrument reveals solar
atmospheric fluctuations at high frequencies. Spectra of variations
of the G-band intensity (IG ) and Ca II K-line intensity
(IK ) show correlated fluctuations above white noise to
frequencies beyond 300 mHz and 50 mHz, respectively. The noise-corrected
G-band spectrum for f = 28-326 mHz shows a power law with exponent -1.21
± 0.02, consistent with the presence of turbulent motions. G-band
spectral power in the 25-100 mHz ("UHF") range is concentrated at
the locations of magnetic bright points in the intergranular lanes
and is highly intermittent in time. The intermittence of the UHF
G-band fluctuations, shown by a positive kurtosis κ, also suggests
turbulence. Combining values of IG , IK , UHF
power, and κ reveals two distinct states of the solar atmosphere. State
1, including almost all the data, is characterized by low IG
, IK , and UHF power and κ ≈ 6. State 2, including only a
very small fraction of the data, is characterized by high IG
, IK , and UHF power and κ ≈ 3. Superposed epoch analysis
shows that the UHF power peaks simultaneously with spatio-temporal
IG maxima in either state. For State 1, IK
shows 3.5 minute chromospheric oscillations with maxima occurring 21
s after IG maxima implying a 150-210 km effective height
difference. However, for State 2 the IK and IG
maxima are simultaneous; in this highly magnetized environment sites
of G-band and K-line emission may be spatially close together.
Title: Modeling Seismic Energy Propagation in a Highly Scattering Moon
Authors: Blanchette-Guertin, J.; Johnson, C. L.; Lawrence, J.
Bibcode: 2011AGUFM.P33A1744B
Altcode:
The propagation of seismic energy in a highly scattering medium can
be modeled using an adapted version of the seismic phonon method. This
method tracks billions of particles from the source to the receiver, and
calculates the seismic energy recorded at each time and location. We use
this technique to generate high frequency (up to ~40 Hz) synthetic
seismograms for a range of lunar interior models, and seismic
sources corresponding to those measured by the Apollo Passive Seismic
Experiment (APSE). Interior structure is specified via 1-D density,
seismic velocity and intrinsic attenuation profiles, as well as suites
of scattering models. Several scattering parameters (e.g., mean path
length between scatterers, thickness of scattering layers, location
of scattering layers) and their effect on the resulting seismograms
are investigated. We filter and resample the synthetic seismograms,
to account for the limited bandwidth, sampling frequency and 10-bit
digitization of the APSE instruments. Signal attributes indicative
of the attenuation and scattering properties of the lunar subsurface
are measured from the synthetic signals, and quantitatively compared
with the results from similar analyses applied to the APSE data. These
attributes are the characteristic decay time of the signal envelope
(the time it takes for the envelope amplitude to drop by a factor of
e), the frequency-dependent coda decay factor (Qc), as well as the P-
and S-rise times. We present lunar interior models that predict coda
characteristics observed in the APSE data, namely the variation of
the signal attributes with epicentral distance, frequency and depth.
Title: Effect of Magnetic Fields on Wave Propagation in the Solar
Atmosphere
Authors: Lawrence, John K.; Cadavid, A. C.; Christian, D. J.
Bibcode: 2011SPD....42.1729L
Altcode: 2011BAAS..43S.1729L
We studied 1 - 24 mHz intensity fluctuations in 3-hour sequences of
high-cadence, high-resolution, broad-band filtergram images taken by the
SOT-FG on board the Hinode spacecraft. The observations consist of near
simultaneous, co-registered G-band (GB), Ca II H-line (HL) intensity
images, and line-of-sight magnetic images calibrated to Gauss with
MDI magnetograms. GB is typically used as a proxy for magnetic fields
while HL is a diagnostic of chromospheric heating. We estimate the
height z1 of the "magnetic canopy,” where magnetic and gas pressures
balance, using potential field extrapolation and the Fontenla 2006
model atmosphere. When z1 is above the height of formation of both
signals, the coherence of the GB and HL oscillations is strong for
frequencies between 3 mHz and 6 mHz and maximal near 5 mHz, around the
acoustic cutoff frequency. Near 3 mHz there is no time delay between
the HL and GB signals indicating a pure standing wave. Above 7 mHz
the time delay settles near 20 sec indicating an upward propagating
acoustic wave. When z1 is below the GB and HL heights of formation the
coherence between the signals drops and has a maximum near 4 mHz. The
time delay remains zero at 3 mHz, but above 7 mHz it is less than 20
sec and decreases with frequency, suggesting that the original acoustic
fluctuations have undergone mode conversion. A similar analysis
of ground-based data acquired with the Rapid Oscillations in the Solar
Atmosphere (ROSA) instrument at the Dunn Solar Telescope finds longer
time delays of 34 sec when z1 is high and 21 sec when z1 is low. This
is consistent with the greater effective formation height of the ROSA
narrowband (1 Å) Ca II K-line core compared to the more broadband
(3 Å) H-line in the Hinode data.
Title: Rapid Oscillations in the Solar Atmosphere: Spectra and
Physical Effects
Authors: Lawrence, John K.; Christian, D. J.; Cadavid, A. C.; Jess,
D. B.; Mathioudakis, M.
Bibcode: 2011SPD....42.1727L
Altcode: 2011BAAS..43S.1727L
High-frequency fluctuations are observed with the Rapid Oscillations in
the Solar Atmosphere (ROSA) instrument (Jess et al. 2010, Solar Phys,
261, 363) at the Dunn Solar Telescope. This can produce simultaneous
observations in up to six channels, at different heights in the
photosphere and chromosphere, at an unprecedentedly high cadence of 0.5
seconds, and at a spatial resolution of 100 km after photometrically
correct speckle reconstruction. Here we concentrate on observations
at two levels. The first is in the G-band of the CH radical at 4305.5Å,
bandpass 9.2Å, with height of formation z < 250 km at a cadence
of 0.525 sec corresponding to Nyquist frequency 950 mHz. The second
is in the Ca II K-line core at 3933.7Å, bandpass 1.0Å, with height
of formation z < 1300 km, and cadence 4.2 sec giving Nyquist
frequency 120 mHz. The data span 53 min, and the maximum field of
view is 45 Mm. The data were taken on 28 May 2009 in internetwork
and network near disk center. Using both Fourier and Morlet
wavelet methods we find evidence in the G-band spectra for intensity
fluctuations above noise out to frequencies f >> 100 mHz. The
K-line signal is noisier and is seen only for f < 50 mHz. With
wavelet techniques we find that G-band spectral power with 20 <
f < 100 mHz is clearly concentrated in the intergranular lanes and
especially at the locations of magnetic elements indicated by G-band
bright points. This wavelet power is highly intermittent in time. By
cross-correlating the data we find that pulses of high-frequency G-band
power in the photosphere tend to be followed by increases in K-line
emission in the chromosphere with a time lag of about 2 min.
Title: Space - Time Distribution of G-band and Ca II H-line Intensity
Oscillations in Hinode/SOT - FG Observations
Authors: Lawrence, J. K.; Cadavid, A. C.
Bibcode: 2010SoPh..261...35L
Altcode: 2009arXiv0907.5001L
We study the space - time distributions of intensity fluctuations in 2
- 3 hour sequences of multi-spectral, high-resolution, high-cadence,
broad-band filtergram images of the Sun made by the SOT - FG system
aboard the Hinode spacecraft. In the frequency range 5.5<f<8.0
mHz both G-band and Ca II H-line oscillations are suppressed in
the presence of magnetic fields, but the suppression disappears for
f>10 mHz. By looking at G-band frequencies above 10 mHz we find
that the oscillatory power, both at these frequencies and at lower
frequencies, lies in a mesh pattern with cell scale 2 - 3 Mm, clearly
larger than normal granulation, and with correlation times on the order
of hours. The mesh pattern lies in the dark lanes between stable cells
found in time-integrated G-band intensity images. It also underlies
part of the bright pattern in time-integrated H-line emission. This
discovery may reflect dynamical constraints on the sizes of rising
granular convection cells together with the turbulence created in
strong intercellular downflows.
Title: Magnetic and Dynamical Properties of Intensity Oscillations
in the Lower Solar Atmosphere
Authors: Cadavid, A. C.; Lawrence, J. K.
Bibcode: 2009AGUFMSH51A1259C
Altcode:
We study 1 - 24 mHz intensity fluctuations in 2-3 hour sequences of
high-cadence, high-resolution images taken by the SOT-FG on board
Hinode. The observations consist of near simultaneous, co-registered
G-Band (GB), Ca II H-Line (HL), and line-of-sight polarization density
(V/I) images. MDI full-disk and high-resolution magnetograms are used
to calibrate the V/I to magnetic field in Gauss. This equips us to
compare fluctuations in magnetic and non-magnetic regions, as well as to
study recently discovered patterns of enhanced oscillatory power in the
photosphere and chromosphere. Oscillatory power in non-magnetic regions
of HL images peaks at ~5 mHz, characteristic of an acoustic signal. As
magnetic field increases up to ~ 200 G the spectrum is significantly
diminished in strength, with a shift toward lower frequencies ~ 4 mHz
starting between 100 - 200 G. In GB images the magnetic spectrum is
dominant below ~3 mHz, perhaps due to contributions from GB bright
points, while in non-magnetic regions the acoustic contribution
peaks at ~ 4 mHz. To further investigate these effects we estimate
the height of the “magnetic canopy,” where plasma β≈1, via
potential field extrapolation from calibrated magnetic images and
the VAL 3C or more recent model atmospheres. We then segregate the
various contributions to the power according to whether the signal
originates above or below the canopy. We have found previously that
GB oscillatory power at frequencies above 10 mHz lies in a mesh-like
pattern with characteristic cell scale 2 - 3 Mm, larger than normal
granulation, and with correlation times on the order of hours. By
appropriate segregation of image pixels we find that at the sites
of enhanced > 10 mHz GB spectral power, there is in fact excess
spectral power at all frequencies, both in GB and HL.
Title: G-Band Bright Point Oscillations Underlying Chromospheric Ca
II H-Line Emission
Authors: Lawrence, John K.; Cadavid, A. C.
Bibcode: 2009SPD....40.1004L
Altcode:
We study the spatial distributions of oscillatory power and of
emission in two sequences of high-cadence, high-resolution images
taken by the Solar Optical Telescope on board Hinode. The sequences
consist of simultaneous, co-registered G-Band (GB) and Ca II H-Line
(HL) images with pixel scale 80 km and fields of view 40 x 40 Mm
and 80 x 40 Mm. The first sequence has cadence 21 s over 3 hours on
2007 April 14; the other has cadence 24 s over 2 hours on 2007 March
30. Both sequences include network and internetwork at heliocentric
angle 35 degrees. The G-Band images were filtered to emphasize
the smallest features and thus to isolate phenomena connected to the
G-Band bright points (GBPs). These appear in intergranular lanes and
are associated with magnetic elements. The filtered G-Band images
serve to segment areas in H-Line and magnetic images and therefore
to explore their connections to the GBPs. Time averaged Morlet
wavelet transforms give smoothed Fourier spectra for each spatial
location in the data. Averaging over four different frequency bands
highlights different physical regimes: "evolutionary” timescales (f
< 1.2 mHz); evanescent frequencies just below the acoustic cutoff
(2.6 mHz < f < 4.2 mHz); high frequencies just above the cutoff
(5.5 mHz <f 10mHz). These last frequencies require data cadences
< 50 s. Spectral images for the filtered GBP data show that the
associated spectral power is greatest in the evanescent frequency
band. The apparent absence of magnetic shadowing suggests non-acoustic
waves. An image of time-integrated H-Line emission shows strong and
detailed correlation with the spatial distribution of spectral power
in the GBP data, thus suggesting a possible energy source.
Title: Sources and Propagation of High Frequency Waves in the Solar
Photosphere and Chromosphere
Authors: Lawrence, John K.; Cadavid, A. C.
Bibcode: 2009SPD....40.1002L
Altcode:
We study the spatial distribution of oscillatory power in two sequences
of high-cadence, high-resolution images taken by the Solar Optical
Telescope on board Hinode. The sequences consist of simultaneous,
co-registered G-Band (GB) and Ca II H-Line (HL) images with pixel
scale 80 km and fields of view 40 x 40 Mm and 80 x 40 Mm. The first
sequence has cadence 21 s over 3 hours on 2007 April 14; the other
has cadence 24 s over 2 hours on 2007 March 30. Both sequences include
network and internetwork at heliocentric angle 35 degrees. Time
averaging of Morlet wavelet transforms gives smoothed Fourier spectra
for each spatial location in the GB and HL data. We averaged over four
different frequency bands to highlight different physical regimes:
"evolutionary” timescales (f < 1.2 mHz); evanescent frequencies
just below the acoustic cutoff ( 2.6 mHz < f < 4.2 mHz); high
frequencies just above the cutoff (5.5 mHz <f 10mHz) These last
frequencies require data cadences < 50 s. The evanescent and
high frequency spectral images display clear magnetic shadowing in both
GB and HL channels, though more strongly in the HL. Thus the heights at
which the GB and HL are formed must both straddle the magnetic canopy,
with the HL higher up. Interestingly, in the VHF band the magnetic
shadowing is markedly weakened. The VHF case shows GB power in the
internetwork that is arranged in the boundary web of a cellular pattern
with scales 2 - 3 Mm. These are found to coincide with the boundaries
of stable clusters of granules. These dark boundaries may correspond
to downflows that control the cell structuring and that could be the
source of acoustic power.
Title: Phase And Time Lags Between G-band, H-line And Magnetic
Fluctuations In The Photosphere And Chromosphere
Authors: Cadavid, Ana Cristina; Lawrence, J.
Bibcode: 2009SPD....40.1003C
Altcode:
We study the oscillatory power in two sequences of high-cadence,
high-resolution images taken by the SOT on board Hinode. The sequences
consist of simultaneous, co-registered G-Band (GB), Ca II H-Line (HL),
and the absolute value of line-of-sight magnetic field (|B|) images,
with pixel scale 80 km and fields of view 40 x 40 Mm and 80 x 40 Mm. The
first sequence has cadence 21 s over 3 hours on 2007 April 14; the
other has cadence 24 s over 2 hours on 2007 March 30. Both sequences
include network and internetwork at heliocentric angle 35 degrees. We investigate phase relations between fluctuations of pairs of the
three data sets as functions of their common frequencies. The height Z1
of the "magnetic canopy,” where plasma beta equal 1, is estimated via
a potential field extrapolation and the VAL 3C model atmosphere. The
phase shifts at each frequency are taken as the maxima of normalized
histograms made by binning the phase shifts for all space-time pixels
segregated by high or low Z1. We interpret the phase shifts as a
constant phase shift plus a constant time shift. For Z1 > 1.3 Mm G
leads H with a constant time lag of 10 sec for frequencies above the
acoustic cut-off, suggesting propagating acoustic waves. For Z1 <
1.15 Mm the time lag between the G and H signals is smaller. Both G and
H lead the |B| fluctuations by a constant phase shift of 100 degrees for
all Z1. For Z1 < 1.15 G also leads |B| by 3±1 sec and H trails |B|
by 6±1 sec. For Z1 > 1.3 Mm these time lags disappear. Thus we can
locate an effective "height” of |B| about 20 km above GB and of HL
about 40 km above |B|.
Title: Fine Scale, Rapid Dynamics of the Solar Atmosphere from
Space-Based Versus Ground- Based Observations
Authors: Lawrence, J. K.; Cadavid, A. C.
Bibcode: 2008AGUFMSH41A1609L
Altcode:
We compare analyses of multi-wavelength, high-cadence sequences of
high-resolution solar images that are derived from ground-based
observations and from space-based observations. The original
analyses aim to show the effects of magnetism on the propagation of
wave energy from the photosphere into the solar atmosphere. Here we
focus on differences that arise from the differing circumstances of
the data acquisition. The ground-based data are a 9 hour sequence of
Swedish Vacuum Solar Telescope filtergram images made on 1998 May 30
in the photospheric G-band and in the chromospheric CaII K-line with
21 s cadence. Atmospheric distortion was removed by phase diversity
reconstruction, and the images were 4 x 4 square averaged to a spatial
resolution of 0.24 Mm/px. A sequence of line-of-sight magnetograms had
lesser resolution and longer cadence. The primary space-based data are
a 6 hour sequence at 1 min cadence of Hinode SOT-FG images in G-band
and CaII H-line and line-of-sight magnetic field, made on 2007 May
2. For space-based data phase reconstruction is irrelevant. The spatial
scale is 0.08 Mm/px but can be averaged to lower resolutions. The
relative phases of oscillations in the different data channels and the
correlations between oscillation periods and spectral intensities show
significant differences between the space- and ground-based cases. These
differences may come partly from terrestrial atmospheric fluctuations
that, in spite of phase reconstruction, act to artificially strengthen
correlations among the ground-based data channels. For example, the
photospheric and the chromospheric intensity fluctuations are more
strongly correlated in the ground data than in the space data. The
relative phases of oscillations in the three data channels show some
different dependences on magnetic field strength between the two
cases. This may be attributable to the higher quality of the available
space magnetic data.
Title: Quasi-periodic patterns coupling the Sun, solar wind and
the Earth
Authors: Ruzmaikin, Alexander; Cadavid, Ana Cristina; Lawrence, John
Bibcode: 2008JASTP..70.2112R
Altcode:
The spectrum of velocity and magnetic fields in the solar wind is
self-similar (power-law type) in the frequency range greater than
>1/day indicating well-mixed turbulence. But it loses self-similarity
for lower frequencies indicating the presence of large-scale patterns,
which are intermittently generated inside the Sun and propagate from the
Sun to the Earth. Here we discuss the spatia-temporal characteristics
and origin of the 1.3-year quasi-periodic pattern found inside the Sun
by helioseismic methods and detected in the solar wind. To identify
and characterize this pattern on the Sun we use time series of solar
magnetic Carrington maps generated at the Wilcox Solar Observatory
and independent component data analysis. This analysis shows the
latitudinal distribution of the pattern, its variable frequency and
intermittent appearance.
Title: Rotational Quasi-Periodicities and the Sun - Heliosphere
Connection
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.
Bibcode: 2008SoPh..252..179L
Altcode: 2008arXiv0803.3260L; 2008SoPh..tmp..138L
Mutual quasi-periodicities near the solar-rotation period appear in
time series based on the Earth's magnetic field, the interplanetary
magnetic field, and signed solar-magnetic fields. Dominant among these
is one at 27.03±0.02 days that has been highlighted by Neugebauer et
al. (J. Geophys. Res.105, 2315, 2000). Extension of their study in
time and to different data reveals decadal epochs during which the
≈ 27.0 days, or a ≈ 28.3 days, or other quasi-periods dominate
the signal. Space-time eigenvalue analyses of time series in 30 solar
latitude bands, based on synoptic maps of unsigned photospheric fields,
lead to two maximally independent modes that account for almost 30%
of the data variance. One mode spans 45° of latitude in the northern
hemisphere and the other one in the southern. The modes rotate
around the Sun rigidly, not differentially, suggesting connection
with the subsurface dynamo. Spectral analyses yield familiar dominant
quasi-periods 27.04±0.03 days in the North and at 28.24±0.03 days
in the South. These are replaced during cycle 23 by one at 26.45±0.03
days in the North. The modes show no tendency for preferred longitudes
separated by ≈ 180°.
Title: Pre-HEAT: submillimeter site testing and astronomical spectra
from Dome A, Antarctica
Authors: Kulesa, C. A.; Walker, C. K.; Schein, M.; Golish, D.;
Tothill, N.; Siegel, P.; Weinreb, S.; Jones, G.; Bardin, J.; Jacobs,
K.; Martin, C. L.; Storey, J.; Ashley, M.; Lawrence, J.; Luong-Van,
D.; Everett, J.; Wang, L.; Feng, L.; Zhu, Z.; Yan, J.; Yang, J.;
Zhang, X. -G.; Cui, X.; Yuan, X.; Hu, J.; Xu, Z.; Jiang, Z.; Yang,
H.; Li, Y.; Sun, B.; Qin, W.; Shang, Z.
Bibcode: 2008SPIE.7012E..49K
Altcode: 2008SPIE.7012E.145K
Pre-HEAT is a 20 cm aperture submillimeter-wave telescope with a 660
GHz (450 micron) Schottky diode heterodyne receiver and digital FFT
spectrometer for the Plateau Observatory (PLATO) developed by the
University of New South Wales. In January 2008 it was deployed to
Dome A, the summit of the Antarctic plateau, as part of a scientific
traverse led by the Polar Research Institute of China and the Chinese
Academy of Sciences. Dome A may be one of the best sites in the world
for ground based Terahertz astronomy, based on the exceptionally cold,
dry and stable conditions which prevail there. Pre-HEAT is measuring
the 450 micron sky opacity at Dome A and mapping the Galactic
Plane in the 13CO J=6-5 line, constituting the first
submillimeter measurements from Dome A. It is field-testing many of the
key technologies for its namesake -- a successor mission called HEAT:
the High Elevation Antarctic Terahertz telescope. Exciting prospects
for submillimeter astronomy from Dome A and the status of Pre-HEAT
will be presented.
Title: Principal Components and Independent Component Analysis of
Solar and Space Data
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A.
Bibcode: 2008SoPh..248..247C
Altcode: 2007arXiv0709.3263C
Principal components analysis (PCA) and independent component analysis
(ICA) are used to identify global patterns in solar and space data. PCA
seeks orthogonal modes of the two-point correlation matrix constructed
from a data set. It permits the identification of structures that remain
coherent and correlated or that recur throughout a time series. ICA
seeks for maximally independent modes and takes into account all
order correlations of the data. We apply PCA to the interplanetary
magnetic field polarity near 1 AU and to the 3.25R⊙
source-surface fields in the solar corona. The rotations of the
two-sector structures of these systems vary together to high accuracy
during the active interval of solar cycle 23. We then use PCA and ICA
to hunt for preferred longitudes in northern hemisphere Carrington
maps of magnetic fields.
Title: Dome A, Antarctica: Prospectives for Terahertz Astronomy from
the Ground
Authors: Kulesa, C. A.; Walker, C. K.; Schein, M.; Golish, D.;
Tothill, N.; Siegel, P.; Weinreb, S.; Jones, G.; Bardin, J.; Jacobs,
K.; Martin, C. L.; Storey, J.; Ashley, M.; Lawrence, J.; Luong-van,
D.; Everett, J.; Wang, L.; Feng, L.; Zhu, Z.; Yan, J.; Yang, J.;
Zhang, X. -G.; Cui, X.; Yuan, X.; Hu, J.; Xu, Z.; Jiang, Z.; Yang,
H.; Li, Y.; Sun, B.; Qin, W.; Shang, Z.
Bibcode: 2008stt..conf..390K
Altcode:
Over a decade of site testing and operation of submillimeter
telescopes has shown that the high Antarctic Plateau (South Pole)
and Chilean Atacama desert (Chajnantor) are exceptional ground-based
sites for submillimeter and terahertz astronomy. The highest sites
at both locations (Dome A and the Chajnantor and Sairecabur summits)
show great promise in yielding even more favorable conditions. To test
the conditions at Dome A, we have deployed Pre-HEAT, a 20 cm aperture
submillimeter-wave telescope with a 660 GHz (450 micron) Schottky
diode heterodyne receiver and digital FFT spectrometer for the Plateau
Observatory (PLATO) developed by the University of New South Wales. In
January 2008 it was deployed to Dome A, the summit of the Antarctic
plateau, as part of a scientific traverse led by the Polar Research
Institute of China. Dome A may be one of the best sites in the world
for ground based Terahertz astronomy, based on the exceptionally cold,
dry and stable conditions which prevail there. Pre-HEAT is measuring the
450 micron sky opacity at Dome A and mapping the Galactic Plane in the
13 CO J=6-5 line, constituting the first submillimeter measurements
from Dome A. It is field-testing many of the key technologies for
its name sake, a successor mission called HEAT: the High Elevation
Antarctic Terahertz telescope. Exciting prospects for submillimeter
astronomy from Dome A and the status of Pre-HEAT will be presented.
Title: The Dome C Gattini sky brightness cameras: results from the
first year of operation
Authors: Moore, A. M.; Leslie, T.; Ashley, M. C. B.; Aristidi, E.;
Bedding, T.; Briguglio, R.; Busso, M.; Candidi, M.; Cutispoto, G.;
Distefano, E.; Everett, J.; Kenyon, S.; Lawrence, J.; Le Roux,
B.; Luong-van, D.; Phillips, A.; Ragazzoni, R.; Sabbatini, L.;
Salinari, P.; Stello, D.; Storey, J. W. V.; Taylor, M.; Tosti, G.;
Travouillon, T.
Bibcode: 2008EAS....33...13M
Altcode:
The Gattini-DomeC project, part of the IRAIT site testing campaign and
ongoing since January 2006, consists of two cameras for the measurement
of optical sky brightness, large area cloud cover, and auroral detection
above the DomeC site, home of the French-Italian Concordia station. The
cameras are transit in nature and are virtually identical except for
the nature of the lenses. The cameras have operated throughout the past
two Antarctic winter seasons and here we present the results obtained
from the 2006 winter-time dataset of the wide field “All-sky camera".
Title: Search for Persistent Quasi-Periodicities in the Solar and
Interplanetary Magnetic Fields
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.
Bibcode: 2007AGUFMSH23A1165L
Altcode:
Previous analysis of the radial component of the interplanetary magnetic
field from 1962 - 1998 has revealed a dominant frequency of 27.03 days
to 0.02 day accuracy (Neugebauer, et al., 2000). We have repeated and
extended this analysis with OMNI data from 1963 - 2007 obtained from the
Coordinated Heliospheric Observations (COHO) database. Over this longer
data string we find that the 27.03 day Lomb-Scargle periodogram peak
is reduced while two side peaks near 26.8 days and 27.6 days become
almost as strong. In the interval 1999-2007 there are two dominant
periods near 26.5 days and 27.2 days. As a solar counterpart to the
above analysis we have searched for persistent rotation periods near
27 days of global patterns of photospheric magnetic fields derived from
Wilcox Solar Observatory synoptic Carrington rotation maps. Techniques
applied include, principal components analysis, independent component
analysis, singular spectrum analysis, wavelet spectral analysis,
and complex demodulation. We find a variety of quasi- periodicities
between 26 and 29 days that remain coherent for 1 - 2 years. In the
southern solar hemisphere the strongest periodicity is at 28.2 days,
while in the northern hemisphere it is around 26.5 days. Neugebauer,
M., Smith, Smith, E.J., Ruzmaikin, A., Feynman, J., Vaughan, A.H. 2000,
J. Geophys. Res., 106, A5, 8363.
Title: The Gattini Cameras for Optical Sky Brightness Measurements
at Dome C, Antarctica
Authors: Moore, A.; Aristidi, E.; Ashley, M.; Briguglio, R.; Busso,
M.; Candidi, M.; Everett, J.; Kenyon, S.; Lawrence, J.; Le Roux, B.;
Luong-van, D.; Phillips, A.; Ragazzoni, R.; Salinari, P.; Storey,
J.; Taylor, M.; Tosti, G.; Travouillon, T.
Bibcode: 2007EAS....25...35M
Altcode:
The Gattini cameras are two site testing instruments for the measurement
of optical sky brightness, large area cloud cover and auroral detection
of the night sky above the high altitude Dome C site in Antarctica. The
cameras have been operating since installation in January 2006 and are
currently at the end of the first Antarctic winter season. The cameras
are transit in nature and are virtually identical, both adopting Apogee
Alta CCD detectors. By taking frequent images of the night sky we
obtain long term cloud cover statistics, measure the sky background
intensity as a function of solar and lunar altitude and phase and
directly measure the spatial extent of bright aurora if present and
when they occur. The full data set will return in December 2006 however
a limited amount of data has been transferred via the Iridium network
enabling preliminary data reduction and system evaluation. An update
of the project is presented together with preliminary results from
data taken since commencement of the winter season.
Title: The thermal state of the Earth
Authors: Lee, C.; Courtier, A.; Halama, R.; Jackson, M.; Larson, A. M.;
Lawrence, J.; Wang, Z.; Warren, J.; Workman, R.; Xu, W.; Hirschmann,
M.; Hart, S.; Stixrude, L.; Lithgow-Bertelloni, C.; Chen, W.
Bibcode: 2006AGUFM.V33D..08L
Altcode:
There is currently a debate over whether the mantle source regions of
"hotspots" are hotter than the ambient mantle. Some of the assumptions
involved in estimating mantle temperatures have been questioned, leading
to the suggestion that temperatures beneath "hotspots" may fall within
the range of that beneath mid-ocean ridges. If "hotspots" are not hot,
the existence of hot thermal plumes originating from a hot lower thermal
boundary layer would be called into question. To shed light on this
debate, we present independent estimates of the potential temperature
of the mantle beneath ridges (ambient) and hotspots. Mantle potential
temperatures were determined in four independent ways: 1) the calculated
primary magma compositions of a global compilation of mid-ocean ridge
basalts (MORBs) and ocean island basalts (OIBs); 2) transition zone
thicknesses from SS precursors and receiver functions, 3) comparisons
between melting models and the average thickness of oceanic crust, and
4) the bathymetry of ridge axes. Primary magma compositions for both
MORBs and OIBs were calculated by incremental equilibrium addition
of olivine back into primitive magmas until an olivine composition
of forsterite 90 was reached. The calculated primary composition was
assumed to represent the aggregate of polybaric fractional melts. The
MgO and SiO2 contents of the primary magma were then used with an
established olivine thermometer and a new barometer based on silica
activity to calculate, respectively, the average temperature and
pressure of equilibration with the mantle. The average potential
temperature of the Earth's mantle based on thermobarometry of MORBs
is 1370 +/- 50 oC. Seismic estimates of the transition zone thickness
coupled with a thermodynamic-based model on how the transition zone
thickness varies as a function of temperature yield a similar mantle
potential temperature. Finally, average mantle potential temperature
inferred from the thickness of oceanic crust and seafloor bathymetry
also fall in this range. In contrast, temperatures of OIBs based on
thermobarometric calculations indicate that they derive from mantle
source regions having potential temperatures at least as high as 1500
+/- 50 oC, suggesting that the OIB source region is 130 oC hotter
than MORB source region (correcting magmas to Fo91 would increase this
temperature difference). OIBs near ridges (Iceland, Azores, Galapagos)
yield temperatures intermediate between 1370 and 1500 oC. Combining
the results from ridges and hotspots reveals a negative correlation
between petrologically-determined potential temperature and seismically
determined transition zone thickness. The sense of this correlation
is consistent with that predicted by mineral physics. The agreement
arrived from these completely independent approaches suggest that the
assumptions involved in our calculations are reasonable. Collectively,
our study provides the most robust estimate so far on the average
potential temperature of the mantle, and moreover, shows that OIBs
derive from mantle source regions, which are at least 130 oC hotter
than ambient mantle. This work comes from the CIDER 2006 conf at the
Kavli Institute.
Title: Quasi-Periodicities, Magnetic Clusters and Solar Activity
Authors: Cadavid, A. C.; Lawrence, J. K.; Sandor, C.; Ruzmaikin, A.
Bibcode: 2006AGUFMSH21A0325C
Altcode:
To investigate quasi-periodicities, 12 hour averages of the radial
component of the interplanetary magnetic field and the solar wind speed,
covering ~ 42 (1963-2005) years were analyzed. A Lomb periodogram for
data up to 1998 showed a dominant period of 27.03 days as fpund in
earlier results. Including cycle 23, a dominant period of 27.06 days
was identified. Analysis of the solar cycles independently showed a
dominant period of 27.03 days in solar cycle 20, but not in the other
cycles. To investigate the degree of persistency of a particular signal,
the technique of complex demodulation was applied since it permits
the determination of continuous changes in time of the amplitude and
frequency of the signal relative to the test signal. It was found that
a period of ~27.6 days gave an overall flat phase function in time,
while other periods < ~0.5 day shorter and longer, with comparable
but lesser amplitude, come and go. To investigate the solar sources
of these periods, the method of principal component analysis (PCA) was
applied to ~ 27 years (1976-2003) of synoptic maps obtained with the NSO
Kitt Peak Vaccum Telescope. Before the analysis, the original synoptic
maps were shifted relative to the previous maps using the period under
investigation. Using PCA the Empirical Orthogonal Functions (EOFs)
and Pricipal Components (PCs) were found for the set of synoptic maps
rescaled to the rotation rate 27.03 days in 1999-2003. The patterns
characterized by EOFs 1 and 2 are mostly axisymmetric and PCs 1 and
2 show solar cycle variability. EOF3 shows only one well-localized
pattern in the Southern Hemisphere which is markedly non-axisymmetric
and PC3 has peaks at times when fast CMEs occur.
Title: Solar Cycle Dependence of Solar Wind Geoeffectiveness
Authors: Lawrence, J. K.; Cadavid, A. C.
Bibcode: 2006AGUFMSH24A..04L
Altcode:
We find clear solar cycle dependence of the specific ways in which
different physical properties of the solar wind (SW) couple to
different aspects of geomagnetic activity. Geomagnetic activity is
described by orthogonalized versions Kp, PC/Kp, and Dst/Kp/PC of
the familiar indices. These represent, respectively, geomagnetic
activity measured at mid-latitudes, geomagnetic activity measured
in the (North) polar region and forced to be linearly independent
of Kp, and finally geomagnetic activity measured at low latitudes
and forced to be independent of both Kp and PC. Solar wind inputs
are hourly averages of the SW plasma beta, dynamical pressure, the
imposed duskward electric field, and a derived parameter related to
nonthermally fast SW structures. These were measured by the Wind and
ACE spacecraft from 1995 through December 2005. They were obtained from
the OMNI2 data set. We connect these quantities using multivatiate
factor analysis. During the active phase of Cycle 23 (1998- 2003)
we find that Kp is primarily governed by SW dynamical pressure, PC/Kp
almost entirely by the imposed electric field, and Dst/Kp/PC by the SW
plasma beta and by nonthermal structures. This result holds separately
for the rising and falling phases of the active Sun. However, during
the preceding quiet Sun period (1995-1997) the nonthermal structures
were unimportant. Then Dst/Kp/PC was governed by the SW plasma beta
and dynamical pressure. At the same time, Kp was coupled directly to
SW pressure and electric field, and negatively to plasma beta.
Title: Technology for a remote automated Antarctic observatory
Authors: Ashley, M. C. B.; Lawrence, J.; Storey, J. W. V.; Burton,
M. G.; Hengst, S.; Luong-van, D.
Bibcode: 2006IAUSS...7E..22A
Altcode:
Encouraged by recent data from Dome C station demonstrating the unique
potential of the high Antarctic plateau for astronomy, a number of
international groups intend to deploy telescopes and site testing
instrumentation to various unmanned locations on the Antarctic plateau
within the next few years. These instruments will require a reliable
completely autonomous observatory to provide power, heat, control, and
communications throughout the Antarctic winter. The AASTINO (Automated
Astrophysical Site Testing International Observatory), which was
designed with these goals, was deployed to Dome C in January 2003. It
has successfully demonstrated many of the concepts essential for such
operation. The second generation AASTINO, currently in development,
has an extremely flexible power generation system that can consist of
solar, battery, diesel, and stirling cycle systems. Power and Control
Area Network (CAN) data is available to all scientific instruments
via a universal connector system, simplifying the integration of
instruments developed by diverse research teams and ensuring a more
straightforward deployment process. System monitoring, commands, and
low bandwidth experimental data transfer, is performed via a redundant
Iridium satellite network up-link. Bulk data storage is achieved via
a redundant array of mechanical hard disk drives in an atmospherically
modified enclosure, preventing damage by low pressure and temperature. A
dual redundant supervisor system controls all aspects of communication
and control, and can handle individual system failures as well as many
catastrophic computer failures. In the event of total communication
loss, the supervisor system is designed to control all experiments
autonomously including the rationing of electrical power.
Title: Stratospheric wave-mean flow interaction: Simple modeling
Authors: Ruzmaikin, Alexander; Cristina Cadavid, Ana; Lawrence, John K.
Bibcode: 2006JASTP..68.1311R
Altcode: 2006JATP...68.1311R
We show that the interaction between planetary waves and the
stratospheric zonal mean flow results in bi-modal (direct-reverse
flow) or unimodal state depending on wave number of the waves. First
we demonstrate this using a simple non-linear dynamic system of the
wave-flow interaction, which has two stable equilibrium states and one
unstable state (attractors) in its phase space. Then we compare this
model dynamics with the stratosphere dynamics using the same dynamical
variables and a similar parameter range in the National Centers for
Environmental Prediction (NCEP) Reanalysis data. This comparison
supports the tendency for the states of planetary wave zonal mean
flow in the upper stratosphere to be bi-modal for wave number 2 and
unimodal for wave number 1.
Title: The Gattini cameras for optical sky brightness measurements
in Antarctica
Authors: Moore, A.; Arisitidi, E.; Ashley, M. C. B.; Busso, M.;
Candidi, M.; Lawrence, J.; Storey, J.; Le Roux, B.; Ragazzoni, R.;
Salinari, P.; Tosti, G.; Travouillon, T.; Kenyon, S.; Luon-van, D.
Bibcode: 2006IAUSS...7E..28M
Altcode:
The Gattini cameras are two site testing instruments for the
measurement of optical sky brightness, large area cloud cover and
auroral detection of the night sky above the high altitude Dome C
site in Antarctica. The cameras have been in operation since January
2006. The cameras are transit in nature and are virtually identical,
both adopting Apogee Alta ccd detectors. The camera called Gattini-SBC
images a 6 degree field centred on the South Pole, an elevation of
75^o at the Dome C site. The camera takes repeated images of the same 6
degree field in the Sloan g' band (centred on 477nm) and, by adopting
a lens with sufficiently long focal length, one can integrate the sky
background photons and directly compare to the equivalent values of
the stars within the field. The second camera, called Gattini-allsky,
incorporates a fish-eye lens and images ~110 degree field centred on
local zenith. By taking frequent images of the night sky we will obtain
long term cloud cover statistics, measure the sky background intensity
as a function of solar and lunar altitude and phase and directly measure
the spatial extent of bright aurora if present and when they occur. An
overview of the project is presented together with preliminary results
from data taken since operation of the cameras in January 2006.
Title: PILOT: optical configuration and instrumentation
Authors: Lawrence, J.; Ashley, M. C. B.; Burton, M. G.; Storey,
J. W. V.
Bibcode: 2006IAUSS...7E..33L
Altcode:
PILOT, the Pathfinder for an International Large Optical Telescope,
is proposed as a 2.4 m diameter optical/infrared telescope to be
located at Dome C, Antarctica. PILOT will be placed on a 30 m high
tower to minimise the effect of the turbulent atmospheric boundary
layer, and should experience the best seeing conditions and the lowest
infrared background of any telescope on earth. To take advantage of
these conditions, we propose an optical configuration able to deliver
diffraction-limited images in the visible, while also giving excellent
wide-field performance. We also present a straw-man instrument suite
for PILOT.
Title: Atmospheric scintillation at Dome C, Antarctica: implications
for photometry and astrometry
Authors: Kenyon, S.; Lawrence, J.; Ashley, M. C. B.; Storey, J. W. V.;
Tokovinin, A.; Fossat, E.
Bibcode: 2006IAUSS...7E..30K
Altcode:
Night-time turbulence profiles of the atmosphere above Dome C,
Antarctica, were measured during 2004, using a MASS instrument. We
compare this data with turbulence profiles above Cerro Tololo and
Cerro Pachon, also measured with a MASS, and find, with the exception
of the owest layer, that Dome C has significantly less turbulence. In
addition, the integrated at turbulence 16 km above Dome C is always
less than the median values at the two Chilean sites. Using average
wind speed profiles, we assess the photometric noise produced by
scintillation, and the atmospheric contribution to the error budget
in narrow angle differential astrometry. In comparison with the
two mid-latitude sites in Chile, Dome C offers a potential gain of
about 3.6 in both photometric precision (for long integrations) and
narrow-angle astrometry precision. Although the data from Dome C cover
a fairly limited time frame, they lend strong support to expectations
that Dome C will offer significant advantages for photometric and
astrometric studies.
Title: PLATO - the next-generation AASTINO for robotic site-testing
on the Antarctic plateau
Authors: Hengst, S.; Lawrence, J.; Luong-van, D.; Everett, J.; Ashley,
M. C. B.; Storey, J. W. V.; Hall, S.
Bibcode: 2006IAUSS...7E..32H
Altcode:
A new site-testing facility, PLATO (Plateau Observatory), is
under development at UNSW for deployment to remote sites on the
Antarctic Plateau including Dome A. The new facility will adopt
many of the features of the AASTINO (Automated Astrophysical Site
Testing InterNational Observatory) facility at Dome C. PLATO will
autonomously control a flexible site testing and observing instrument
suite, monitored via the Iridium satellite network. A challenging
aspect of PLATO is to maximise the reliability of the power source
while minimising fuel consumption. We are building a low pressure,
low temperature environmental chamber to simulate operation at the
highest altitudes (4,100 m at Dome A). Two types of engines will be
tested: a single-cylinder diesel engine and a Stirling engine.
Title: LAPCAT: the Large Antarctic Plateau Clear-Aperture Telescope
Authors: Storey, J. W. V.; Angel, R.; Lawrence, J.; Hinz, P.; Ashley,
M. C. B.; Burton, M. G.
Bibcode: 2006IAUSS...7E..31S
Altcode:
We present a proposal for an 8.4 metre off-axis optical/IR telescope to
be located at Dome C, Antarctica. LAPCAT will use a mirror identical
to the offset segment recently cast for the Giant Magellan Telescope
(GMT) as a completely unobscured f/2.1 primary. With a cooled deformable
Gregorian secondary in a dewar following prime focus, LAPCAT will allow
for diffraction-limited imaging with only a single reflecting surface
at ~ 220K, and thus the lowest possible thermal background obtainable on
earth. The exceptionally low atmospheric turbulence above Dome C enables
very high contrast imaging in the thermal infrared, and diffraction
limited imaging extending to optical wavelengths (20 mas at 800 nm,
where Strehl ratios > 60% are projected). As an example, a deep 5 mm
exoplanet imaging survey to complement current radial velocity methods
could take advantage of both the low background and pupil remapping
methods for apodization enabled by the clear aperture. Many new, young,
giant planets (? 3MJ at 1 Gyr) would be detected in orbits ? 5 AU out
to 20 pc. By providing a test bed for many of the GMT technologies in
an Antarctic environment, LAPCAT also paves the way for the eventual
construction of a second GMT at Dome C. Such a telescope would have
unparalleled capabilities compared both to other ELTs in temperate
sites and to JWST.
Title: Persistent Peridicities in the Solar Wind and Photospheric
Magnetic Field Coherent Structures
Authors: Cadavid, Ana C.; Lawrence, J. K.; Ruzmaikin, A.
Bibcode: 2006SPD....37.1106C
Altcode: 2006BAAS...38..239C
To investigate persistent periodicities, 12-hour averages of the
radial component of the interplanetary magnetic field and the solar
wind speed, covering 42 years (1963-2005), were analyzed. A Lomb
periodogram for the data up to 1998 showed maximum spectral power at
a period of 27.03 days, as encountered previously by Neugebauer et
al. (2000). Including cycle 23 shifted the peak to 27.06 days. Analysis
of solar cycles 20 - 23 separately showed a dominant period of 27.03
days in solar cycle 20, but not in the other cycles.To investigate
the degree of persistency and phase coherence of a particular signal,
the technique of complex demodulation was applied since it permits
the determination of continuous changes in time of the amplitude and
frequency of the signal relative to a test signal. It was found that
for a reference signal of 27.03 days, the phase was a flat function of
time during the intervals 1965-1972 and 1995-1997. The phase decreased
in time from 1972-1995 and increased after 1997. This implies that
for the intervals 1972-1995 and 1997-2005 other periodicities better
characterize the data. A period of 27.6 days gave an overall flat phase
function in time, while other periods < 0.5 day shorter and longer,
with comparable but lesser amplitude, come and go.To investigate the
solar sources of these periods, the methods of principal component
analysis (PCA) and independent component analysis (ICA) were applied
to 27 years (1976-2003) of synoptic maps obtained with the NSO Kitt
Peak Vacuum Telescope. Before the analysis, the original synoptic
maps were shifted relative to the previous maps using the particular
period under investigation. PCA and ICA identified 3 modes for the
27.03 reference period and 2 modes for the 27.6 period that showed
clusters of magnetic activity at preferred longitudes.
Title: What a Really Big Antarctic Telescope could Achieve
Authors: Storey, J.; Ashley, M.; Burton, M.; Lawrence, J.
Bibcode: 2006via..conf...61S
Altcode:
Despite its diminutive size, the 60 cm SPIREX telescope at the
South Pole produced a wealth of important publications from just two
seasons of operation. What could a 2 m, 8 m, or even 25 m telescope
achieve? With infrared sky backgrounds up to two orders of magnitude
below those of the best temperate sites, plus cleaner, wider and
more stable atmospheric windows, the Antarctic plateau provides a
remarkable opportunity for the deployment of the next generation
of ground-based telescopes. In addition to the obvious sensitivity
gains, the atmospheric turbulence profile above Dome C has now been
measured by two groups using independent techniques. The results are in
excellent agreement and promise unrivalled spatial resolution across
wide fields of view, and unbeatable levels of speckle suppression
over small fields. Will the first direct detection of an earth-like
exoplanet be achieved by an Antarctic telescope? If so, how big does
this telescope need to be?
Title: Solar Wind Interaction and Orthogonal Magnetospheric Indices
Authors: Lawrence, J. K.; Cadavid, A. C.
Bibcode: 2005AGUFMSM43A1214L
Altcode:
Multivariate methods can help to untangle connections between indices
of magnetospheric activity and solar wind (SW) parameters. The data are
3-hour resolution time series spanning the period 1996 JAN 25 to 2004
SEP 17. The time series include Kp, the Dst and PC (polar cap) indices
and an auroral POES index derived from NOAA satellite observations,
plus OMNI SW data. The Kp index correlates with many other indices
of magnetospheric activity due to its association with the convection
electric field (see the survey in Thomsen 2004). We find correlation
coefficients C(Kp,PC)=0.57, C(Dst,Kp)=-0.44 and C(Dst,PC)=-0.37. POES
correlations are small. We replace PC with a variable PC/Kp containing
that part of PC orthogonal to Kp. Likewise we replace Dst with Dst/KpPC,
orthogonal to both Kp and to PC/Kp. The independent indices behave
very differently from the original ones. Factor analysis gives five
latent factor modes relating the terrestrial and SW sets. (1) The only
factor containing the solar cycle connects sunspot number fluctuations
to POES and PC/Kp only. This is the only factor containing POES or
PC/Kp, so these vary mainly together. (2) Only one factor contains
the south IMF, and this connects its fluctuations to Kp only. (3)
A third factor relates strong responses in Dst/KpPC to increases
in SW ram pressure, temperature and to alpha/proton ratio, an
indicator of solar ejecta in the SW. (4) A fourth factor relates
strong responses in Dst/KpPC to increases in excess SW coolness,
another indicator of solar ejecta, along with drops in mean IMF, SW
ram pressure and plasma beta. (5) The fifth factor relates increases
in Kp to increased mean IMF, SW speed, coolness and plasma beta. We
present a path analysis calculation quantifying the web of causal
relations between the SW and the independent terrestrial indices via
the intermediate latent factors. Thomsen, M.F. 2004, Space Weather,
2, S11004, doi:10.1029/2004SW000089
Title: Coherent Structures vs Independent Modes of the Axisymmetric
Magnetic Field Fluctuations
Authors: Cadavid, A. C.; Lawrence, J. K.; McDonald, D. P.; Ruzmaikin,
A.
Bibcode: 2005ASPC..346...91C
Altcode:
Quasi periodicities on scales of 1 to 2.5 years have been observed in
solar, interplanetary and geomagnetic time series. The relation of
these signals to 1 and 1.3 yr fluctuations in the solar interior,
suggest the presence of structures or characteristic modes in
the magnetic field, generated by the dynamo, that extend into the
heliosphere. We have applied the methods of principal component
analysis (PCA) and independent component analysis (ICA) to search
for the coherent structures (PCA) and independent global modes (ICA)
of the axisymmetric solar magnetic field. While PCA is effective in
identifying the coherent modes that describe the 22 yr solar cycle,
ICA uncovers the independent global modes the with characteristic 1 to
2.5 yr quasi periods observed in heliospheric and helioseismic time
series. Five modes capture the salient properties of the data. Two
modes describe the polar and high latitude fields, and present 1-1.5
yr quasi periodicities. The other three modes correspond to low and
mid-latitude phenomena and show both 1.3 yr and 1.7 yr variations.
Title: Quasi periodicities in the Fluctuations of the Axisymmetric
Solar Magnetic Field from Independent Component Analysis
Authors: McDonald, D. P.; Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin,
A.
Bibcode: 2005AGUSMSP43B..05M
Altcode:
Observed solar, interplanetary and geomagnetic time series contain quasi
periodicities on the order of 1 to 2.5 years. The further discovery
of 1.3 year fluctuations in helioseismic observations suggests that
a variety of signals may be related to the underlying dynamo in the
Sun. We have applied the methods of principal component analysis (PCA)
and independent component analysis (ICA) to search for the coherent
structures (PCA) and independent global modes (ICA) of the axisymmetric
solar magnetic field. While PCA was shown to be effective in identifying
the coherent modes that describe the 22 yr solar cycle, ICA uncovers the
independent global modes with characteristic 1 to 2.5 yr quasi periods
observed in heliospheric and helioseismic time series. We found that
five modes effectively describe the data in both spatial and temporal
domains. Two modes describe the polar and high latitude fields,
and present 1-1.5 year quasi periodicities. The other three modes
correspond to low and mid-latitude phenomena and show both 1.3 year
and 1.7 year variations. By comparing the characteristic timescales,
dates of occurrence and heliocentric latitudes of these modes, we
connect them to their manifestations in heliospheric time series.
Title: Coherent Structures and Rotation Rates in Coronal Activity,
from Principal Component Analysis
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A.
Bibcode: 2005AGUSMSP21B..07C
Altcode:
Principal component analysis (PCA) offers a way to extract those
structures that remain spatially coherent throughout a time series. We
apply this method to a ~ 28 year time series of Wilcox Solar Observatory
Carrington rotation maps (CR) of the 3.25 R coronal source surface field
obtained via a potential field extrapolation. We find that over 99%
of the variance is contained in the first eight modes. Mode 1, carrying
81.5% of the variance, and modes 2 and 3 containing 13% of the variance,
have "dipole" structures. Modes 4-8, with a "quadruple" structure,
contain 4.5% of the variance. The principal components (PCs) give the
time dependence of the modes. We combine the PCs of modes 2 and 3 to
get the amplitude and phase of a structure that behaves essentially as
a dipole in the equatorial plane. During activity minima the structure
is relatively weak and rotates at the 27.275 day Carrington rate. During
the active periods of cycles 21 and 22 the amplitude is large and highly
intermittent, and the dipole rotates more rapidly than the Carrington
rate with a synodic period of 26.6 days. During cycle 23, however, the
dipole moves backward in Carrington longitude with a synodic period
of 27.8 days. The average of these is ~ 27.0 days, though this is
actually realized only sporadically. The phase changes that occur at
shorter time scales and that coincide with intermittent changes in the
dipole amplitude seem to represent essentially random effects of the
passage of the magnetic field through the convection zone. While the
lower modes tend to lock the hemispheres together the higher modes
present separate Northern and Southern hemisphere quadrupole-type
patterns that drift in Carrington longitude similarly to the equatorial
dipole. Over some periods the drift in each hemisphere closely tracks
the other over a wide range of timescales. However, there are large,
decadal-scale excursions in which first one hemisphere leads in phase
by 3 or 4 rotations and then the other leads by a similar amount.
Title: Magnetic Topology and Wave Propagation in the Solar Atmosphere
Authors: Lawrence, J. K.; Cadavid, A. C.; McIntosh, S. W.; Berger,
T. E.
Bibcode: 2005AGUSMSH13C..01L
Altcode:
We analyze a 9 hr sequence of simultaneous, high resolution, 21 s
cadence SVST G-band and K-line solar filtergrams plus magnetograms
of lower cadence and resolution. The data include both network and
internetwork areas (Berger and Title 2001, Cadavid, et al. 2003,
Lawrence, et al. 2003). Time series of the G-band and K-line data are
compared after filtering by a Morlet wavelet transform of period 2.5
min. On the average, the K-line signal is delayed by several seconds
after the G-band signal Δ T = 8.6 ± 0.1 s for weak (|BZ| < 50 G)
magnetic field in internetwork but Δ T = 7.2 ± 0.1 s for weak field
in an area including network. The internetwork has no strong fields,
but in network (|BZ| > 80 G) the mean delay time drops to Δ T =
3.4 ± 0.3 s. This is consistent with results by McIntosh, Fleck and
Tarbell (2004) using TRACE 1600Å and 1700Å UV image series. Our
principal result is that the time delay is greater in the internetwork
than in the network by 1.4 ± 0.1 s, even for the same local magnetic
field strength. This suggests that the difference must be an effect
of the field topology. Spatial maps of time delays, in comparison
to maps of such topological quantities as the height in the solar
atmosphere at which the plasma β = 1, offer additional details of the
relationship between wave propagation and the magnetic fields in the
solar atmosphere. This work was supported in part by grants NSF-ATM
9987305 and NASA-NAG5-10880. The SVST is operated by the Swedish
Royal Academy of Sciences at the Spanish Observatorio del Roque de
los Muchachos of the Instituto de Astrofisica de Canarias. Berger,
T.E. and Title, A.M. 2001, ApJ, 553, 449. Cadavid, A.C., et al. 2003,
ApJ, 586, 1409. Lawrence, J.K., et al. 2003, ApJ, 597, 1178. McIntosh,
S.W., Fleck, B. and Tarbell, T.D. 2004, ApJ, 609, L95.
Title: Independent Global Modes of Solar Magnetic Field Fluctuations
Authors: Cadavid, A. C.; Lawrence, J. K.; McDonald, D. P.; Ruzmaikin,
A.
Bibcode: 2005SoPh..226..359C
Altcode:
Observed solar, interplanetary and geomagnetic time series contain
quasi periodicities on scales of 1-2.5 years. The further discovery
of 1.3 year fluctuations in helioseismic observations suggests that
a variety of signals may be related to the underlying dynamo in the
Sun. We use independent component analysis to study the temporal and
spatial variations of a few statistically independent global modes of
the axisymmetric solar magnetic field over a period of 25 years. Five
modes capture the salient properties of the data. Two modes describe
the polar and high latitude fields, and present 1-1.5 year quasi
periodicities. The other three modes correspond to low and mid-latitude
phenomena and show both 1.3 and 1.7-year variations. By comparing
the characteristic time scales, dates of occurrence and heliocentric
latitudes of these modes, we connect them to their manifestations in
heliospheric time series.
Title: Principal Component Analysis of the Solar Magnetic Field I:
The Axisymmetric Field at the Photosphere
Authors: Lawrence, John K.; Cristina Cadavid, Ana; Ruzmaikin, Alexander
Bibcode: 2004SoPh..225....1L
Altcode:
A principal component analysis, or proper orthogonal decomposition,
of the axisymmetric magnetic field at the photosphere is carried out to
find an optimal representation of the observed solar cycle. The 22-year
periodic field requires just two modes. NSO Kitt Peak synoptic maps for
Carrington rotations 1664-2007 were reduced by taking both the mean and
the median field over longitude to produce two sequences of functions
of sine latitude spanning 25.7 years. The lowest modes of each are
determined by the polar fields. The mean field is most efficient at
representing the periodic field, but the median field is more efficient
at representing the evolution of the diffuse field patterns.
Title: Principal Component Analysis of the Latitudinal and
Longitudinal Structure of the Photospheric Magnetic Cycle
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.
Bibcode: 2004AAS...204.3708L
Altcode: 2004BAAS...36Q.710L
We average magnetic fields in NSO synoptic maps over longitude and bin
the result by sin(latitude). Also, we average over a band of latitudes
and bin by longitude. A time stack of one-dimensional latitude "images"
resembles the Maunder butterfly diagram. Time stacks of longitude
"images" can be re-mapped to arbitrary rotation periods. Principal
component analysis recombines images in a stack into mutually orthogonal
"empirical orthogonal functions" (EOFs). The EOFs are ordered by
how well each correlates with the full set of images. The principal
components (PCs) give the evolution of each EOF as a function of any
ordering parameter, such as time. The original data can be wholly or
partially reconstructed from subsets of the EOFs and their PCs. Our
latitudinal EOFs have a few leaders whose PCs show both the 11/22-year
cycle and repeating substructure. Following are EOFs whose PCs show
the cycle but no repeated substructure. Next are EOFs with small scale
structure independent of the cycle. The least correlated EOFs contain
high latitude, mostly unipolar fields. We suggest associating these four
subsets of the EOFs with, respectively, global dynamo toroidal fields,
turbulently disordered structures fed by the toroidal fields, a possible
local surface dynamo process, and a global poloidal component. We also studied a stack of longitudinal images of fields that were
averaged over latitude between N25 and N35 degrees. Two especially
active longitudes 180 degrees apart rotate with a period of 27.8
days. Structure at these longitudes dominates the leading EOFs. The
corresponding PCs are active over the whole span of the data. This
work was supported by NASA Grant NAG5-10880. NSO/Kitt Peak data used
here are produced cooperatively by NSF/NOAO, NASA/GSFC, and NOAA/SEL.
Title: Two-dimensional Empirical Orthogonal Functions of the
Photospheric Magnetic Cycle
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A.
Bibcode: 2004AAS...204.3707C
Altcode: 2004BAAS...36Q.710C
We carried out a principal component analysis (PCA) on sequences
of NSO magnetic flux synoptic maps by Carrington rotation. Two
data sets were investigated: (i) a sequence of 364 images from
Carrington rotation 1625 to 2007, with image size 360 x 180 pixels
(1 degree/pixel in longitude and sin(latitude)*90 in latitude for
both hemispheres); (ii) a sequence of 79 higher resolution maps of
size 1800 x 900 pixels starting at Carrington rotation 1913. The PCA
of a time series yields an eigenvalue spectrum, the corresponding
eigenfunctions (modes or "empirical orthogonal functions" (EOFs)),
and the principal components which describe the time evolution of the
modes. The dominant EOFs are associated with those structures that
remain spatially coherent throughout intervals of the time series,
and correspond to the functions with the highest eigenvalues. If the
eigenvalue spectrum is dominated by only a few large members, then
the corresponding few EOFs will mainly characterize the data. The rest
will contain transient fluctuations. We apply the technique to the two
dimensional maps and determine which EOFs dominate during different
times of the solar cycle. We find that the dominant modes are associated
with the active part of the cycle as expected, while the weaker modes
characterize the quiet periods. The increasing and declining phases
are associated with modes of intermediate eigenvalues. We reconstruct
the time series by projecting onto the three classes of modes and
investigate the probability distribution function (PDF) of "projected"
magnetic flux. We compare these results to the PDFs obtained from
artificial data generated by dynamo models. This work was supported
in part by Grant NASA-NAG5-10880. NSO/Kitt Peak data used here are
produced cooperatively by NSF/NOAO, NASA/GSFC, and NOAA/SEL.
Title: A simple model of solar variability influence on climate
Authors: Ruzmaikin, Alexander; Lawrence, John K.; Cadavid, Ana Cristina
Bibcode: 2004AdSpR..34..349R
Altcode:
We present a simple dynamic model of solar variability influence on
climate, which is truncated from the stratospheric wave-zonal flow
interaction dynamics over a β-plane. The model consists of three
ordinary differential equations controlled by two parameters: the
initial amplitude of planetary waves and the vertical gradient of the
zonal wind. The changes associated with the solar UV variability, as
well as with seasonal variations, are introduced as periodic modulations
of the zonal wind gradient. Influence of the Quasi-Biennial Oscillation
is included as a periodic change of the width of the latitudinal extent
of the β-plane. The major climate response to these changes is seen
through modulation of the number of cold and warm winters.
Title: Influence of Photospheric Magnetic Fields and Dynamics on
Chromospheric K-Line Emission
Authors: Lawrence, J. K.; Cadavid, A. C.; Miccolis, D.; Berger, T. E.;
Ruzmaikin, A.
Bibcode: 2003ApJ...597.1178L
Altcode:
We analyze a 9 hr sequence of simultaneous, high-resolution,
high-cadence G-band and K-line solar filtergrams plus magnetograms
of lower cadence and resolution. Images include both network
and internetwork. The magnetic and filtergram intensities, their
fluctuations, and relative phases change with progressive strengthening
of local magnetic field. At increased flux levels, sudden photospheric
downflows create long-lived magnetic elements. For weak magnetic fields
the K-line and G-band intensities include an oscillatory component
with period 4 minutes. For stronger fields, the K-line period shifts
to 5 minutes, while the G-band fluctuations fade due to dissociation
of their source, the CH radical. These K-line and G-band fluctuations,
whose periods are longer than the acoustic cutoff, are coherent and
in phase. They also are coherent with fluctuations of the magnetic
field. Weak-field magnetic fluctuations lead the intensity fluctuations
by a phase shift of 90°. Strong-field magnetic fluctuations trail the
intensities by 100°. These are interpreted as standing waves in the
photosphere and low chromosphere. Another class of G-band fluctuations,
with periods shorter than the acoustic cutoff, is associated both
with stronger magnetic fields and with enhanced K-line emission with
fluctuations longer than the cutoff period. This suggests waves excited
by rapid photospheric perturbations and propagating up along magnetic
flux tubes.
Title: Influence of Photospheric Magnetism and Dynamics on
Chromospheric K-line Emission
Authors: Lawrence, J. K.; Cadavid, A. C.; Miccolis, D.; Berger, T. E.;
Ruzmaikin, A.
Bibcode: 2003SPD....34.0704L
Altcode: 2003BAAS...35..820L
We analyze a unique 9 hr sequence of near simultaneous, high resolution
and high cadence G-band and K-line SVST solar filtergrams together
with magnetograms of lower cadence and resolution. We focus on a
region of the solar surface that includes both internetwork and
network. We examine how the (temperature minimum/chromospheric)
CaII K-line and (photospheric) G-band intensities, their temporal
fluctuations and their coherence and phase relations, with each other
and with magnetic fluctuations, change as we progress from weak magnetic
fields (internetwork) to intermediate and strong fields (network). As the background level of flux is increased, sudden photospheric
downflow events can create long-lived, compact (i.e. network) magnetic
elements. For weak magnetic fields the K-line and G-band intensity
signals show an oscillatory component with period centered on 4 min. As
we pass to strong fields, the K-line signal shifts to a 5 min period
while the G-band signal fades, presumably due to dissociation of the
CH radical. The K-line and G-band signals are coherent and nearly
in-phase. They are both coherent with fluctuations of the magnetic
field. For weak field the magnetic signal leads the intensity signals by
90o in phase. For intermediate and strong fields the magnetic
signal trails the intensities by 110o. We interpret this as
a transition from acoustic standing waves with weak, passive magnetic
field to a slow mode trapped magnetoacoustic wave. For intermediate
magnetic field we find, in addition to the coherent waves, that G-band
fluctuations at frequencies above the acoustic cutoff (period <
3.5 min) are associated with magnetic fields and with K-line emission
at periods > 3.5 min. This suggests the presence of flux tube
waves excited by rapid photospheric perturbations. This work
was supported by grants NSF-ATM 9987305 and NASA-NAG5-10880. The SVST
is operated by the Swedish Royal Academy of Sciences at the Spanish
Observatorio del Roque de los Muchachos of the Instituto de Astrofisica
de Canarias.
Title: A Simple Model of Stratospheric Dynamics Including Solar
Variability.
Authors: Ruzmaikin, Alexander; Lawrence, John; Cadavid, Cristina
Bibcode: 2003JCli...16.1593R
Altcode:
A simple dynamic model, truncated from the stratospheric wave-zonal
flow interaction Holton and Mass model, is introduced and studied. This
model consists of three ordinary differential equations controlled
by two parameters: the initial amplitude of planetary waves and the
vertical gradient of the zonal wind. The changes associated with
seasonal variations and with the solar variability are introduced as
periodic modulations of the zonal wind gradient. The major climatic
response to these changes is seen through modulation of the number of
cold and warm winters.
Title: Photospheric Sources of Chromospheric Dynamics in the
Internetwork
Authors: Cadavid, A. C.; Lawrence, J. K.; Berger, T. E.; Ruzmaikin, A.
Bibcode: 2003SPD....34.0703C
Altcode: 2003BAAS...35..820C
We analyze a unique 9 hr sequence of near simultaneous, high
resolution and high cadence G-band and K-line solar filtergrams
together with magnetograms of lower cadence and resolution, taken
with the SVST. We investigate an internetwork region characterized
by magnetic fields with strength < 150 Gauss and focus on the
phenomena surrounding discrete photospheric darkening ``events''
in G-band intensities. 72 % of the darkenings are followed after 2
min by K-line brightenings. In the remaining cases the darkenings are
instead preceded by K-line brightenings 2 min earlier. In both cases
the preceding and following G-band minima are each associated with
transient magnetic enhancements, and thus, presumably, photospheric
inflows followed by outflows. The magnetic field appears to have no
role in coupling the photospheric phenomena to the chromosphere, and
acts as a passive tracer of horizontal photospheric flows that converge
on the photospheric darkening events and then rebound. The timing and
coupling of the photospheric darkenings and chromospheric brightenings
appear to be regulated by a pre-existing 4 min oscillation of the
solar atmosphere. Other oscillations with periods in the range 1-8
min also are present, and in general the wave power is doubled at the
time of an event. At short periods temporal structure is resolved. Our
results favor an acoustic source for enhanced amplitudes of K-line
intensity oscillations.
Title: Photospheric Sources and Brightening of the Internetwork
Chromosphere
Authors: Cadavid, A. C.; Lawrence, J. K.; Berger, T. E.; Ruzmaikin, A.
Bibcode: 2003ApJ...586.1409C
Altcode:
We analyze a unique 9 hr sequence of near-simultaneous, high-resolution
and high-cadence G-band and K-line solar filtergrams, together with
magnetograms of lower cadence and resolution. Our focus is on the
phenomena surrounding discrete photospheric darkening ``events'' in
internetwork G-band intensities. 72% of the darkenings are followed
after 2 minutes by K-line brightenings. In the remaining cases,
the darkenings are instead preceded by K-line brightenings 2 minutes
earlier. Equivalent results are found when reference is shifted to
K-line brightening events, although these two sets overlap by no more
than 15%. The timing and coupling of the photospheric darkenings and
chromospheric brightenings appear to be regulated by a preexisting 4
minute oscillation of the solar atmosphere. Other oscillations with
periods in the range 1-8 minutes also are present, and in general
the wave power is doubled at the time of an event. Our results
favor an acoustic source for enhanced amplitudes of K-line intensity
oscillations. The magnetic field acts as a passive tracer of horizontal
photospheric flows that converge on the photospheric darkening events
and then rebound.
Title: Low atmosphere turbulence at Dome C. preliminary results
Authors: Travouillon, T.; Ashley, M. C. B.; Burton, M. G.; Lawrence,
J.; Storey, J. W. V.
Bibcode: 2003MSAIS...2..150T
Altcode:
We discuss the first two months of low altitude atmospheric turbulence
at the Antarctic site of Dome C. Using a mini-SODAR, the first 890m
of the atmosphere were sampled. It was found that between 9 Feb and 17
Apr 2003, the turbulence was concentrated below a 120m boundary layer
that exhibited a clear diurnal cycle. This boundary layer height is
less than half as thick as that at the South Pole (270m) as measured
by the same instrument. It was also found that for the same period,
the ground level wind at Dome C was also half that at the South Pole.
Title: Mesogranulation from Principal Component Analysis of SVST
Photospheric Continuum Images
Authors: Bell, E.; Cadavid, A. C.; Lawrence, J. K.; Berger, T. E.
Bibcode: 2002AAS...200.3805B
Altcode: 2002BAAS...34Q.699B
We analyze a sequence of 279 images of the photosphere made with the
Swedish Vacuum Solar Telescope on 1997 June 11. The sequence spans 3
hr with cadence 38 s. The images were taken in continuum near 4364
Å, and underwent phase diversity reconstruction. Resolution is ~
0.2 Mm and field of view 32 X 32 Mm. We carried out a principal
component analysis on sequences of 15 images spaced 6 min apart and
covering 1.5 hr. The 15 X 15 correlation matrix of each such set
of images was diagonalized, giving 15 eigenimages which are linear
combinations of the original 15. The eigenimage corresponding to the
largest eigenvalue is the linear combination that best resembles the
original set as a whole; those with smaller and smaller eigenvalues
resemble the overall set less and less well. Fourier spectra of the
eigenimages were calculated separately for several sequences and
then averaged together to reduce uncertainties. Fourier analysis
of the leading eigenimage reveals structure at two scales: one for
λ =1/ν ~ 1.5 Mm corresponding to granulation and another for λ ~
4.5 Mm. Because of their scale and because the time span of the sets
lies between the lifetimes of granules and mesogranules, we interpret
the latter as mesogranules. The subsequent eigenimages do not show the
larger structure, but show the granular peak at successively smaller
scales. This indicates a spatio-temporal scaling of the granulation
with shorter lifetimes for smaller features. For comparison purposes,
simulated granulation images (Cattaneo, Lenz and Weiss 2001) were
similarly analyzed and give similar results. Work supported in part
by grants NSF-ATM-9987305, NASA-NAG5-10880 and the NASA CSUN/JPL PAIR
Program. F. Cattaneo, D. Lenz and N. Weiss 2001, ApJ, 563, L91.
Title: High Resolution Spatio-Temporal Study of Photospheric and
Chromospheric Energetics
Authors: Cadavid, A. C.; Lawrence, J. K.; Berger, T. E.
Bibcode: 2002AAS...200.3809C
Altcode: 2002BAAS...34..700C
We study the photosphere/chromosphere energetic connection using a
nine hour sequence of SVST images obtained May 30, 1998. The data
consist of co-spatial, nearly simultaneous filtergrams of G-band
(4305 Å ), Ca II K (3934 Å ), two (6563 Å) Hα channels offset by
0.35 Å and 0.7 Å , and Fe I (6302 Å) magnetograms. The cadence of
the G-band and Ca K observations is ~ 30 s; that of the other images
is ~ 2 min. The pixel scale is 0.06 Mm and field of view 48 X 48 Mm
on the Sun. The filtergram resolution is > 0.2 Mm; that of the
magnetograms > 0.3 Mm with single magnetogram sensitivity <
150 G. We have co-registered the images to 1 or 2 pixel accuracy. The
number distribution of Ca brightenings and of localized changes in
magnetic field strength, measured in standard deviations (σ ) from
the image means, present three different characteristic regimes;
that of the magnetic ``free energy'' (a derived measure based on
the local variance of magnetic field) presents two. Ca brightenings
below 3σ show a weak but significant correlation with local magnetic
field and free energy. At 3σ the strength of the correlation abruptly
increases. Above 5σ no correlation is apparent, but large magnetic
field values appear. Using a mask to remove the network areas, the
weakest brightenings (<1.5 σ ) show anti-correlation with the
magnetic field. For 1.5 σ to 4.5 σ there is no correlation. For
selected network examples we follow the time evolution in all observed
lines. We find cases in which an increase and then relaxation in the
magnetic free energy just precedes a local rise in Ca emission followed
by a drop to a lower background level than initially. Work supported
in part by NSF-ATM-9987305 and NASA-NAG5-10880.
Title: Observations of the Structure of small scale photospheric
fields
Authors: Lawrence, J.; Cadavid, A.; Ruzmaikin, A.; Berger, T.
Bibcode: 2002ocnd.confE..26L
Altcode:
No abstract at ADS
Title: A simple model of solar variability influence on climate.
Authors: Ruzmaikin, A.; Lawrence, J.; Cadavid, A.
Bibcode: 2002cosp...34E.336R
Altcode: 2002cosp.meetE.336R
We introduce and study a simple dynamic model of solar influence on
climate. The model is truncated from the stratospheric wave-zonal
flow interaction model suggested by Holton and Mass (1976). Our model
consists of three ordinary differential equations controlled by two
parameters: the initial amplitude of planetary waves and the vertical
gradient of the zonal wind. The changes associated with seasonal
variations and with the solar variability are introduced as periodic
modulations of the zonal wind gradient. The major atmospheric response
to these changes is seen through modulation of the number of cold and
warm winters.
Title: Mesogranulation and Turbulence in Photospheric Flows
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.
Bibcode: 2001SoPh..202...27L
Altcode: 2001astro.ph..4354L
Below the scale of supergranules we find that cellular flows are present
in the solar photosphere at two distinct size scales, approximately 2 Mm
and 4 Mm, with distinct characteristic times. Simultaneously present in
the flow is a non-cellular component, with turbulent scaling properties
and containing 30% of the flow energy. These results are obtained by
means of wavelet spectral analysis and modeling of vertical photospheric
motions in a 2-hour sequence of 120 SOHO/MDI, high-resolution, Doppler
images near disk center. The wavelets permit detection of specific
local flow patterns corresponding to convection cells.
Title: Spatiotemporal Scaling of Solar Surface Flows
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.; Berger, T. E.
Bibcode: 2001PhRvL..86.5894L
Altcode: 2001astro.ph..1224L
The sun provides an excellent natural laboratory for nonlinear
phenomena. We use motions of magnetic bright points on the solar
surface, at the smallest scales yet observed, to study the small scale
dynamics of the photospheric plasma. The paths of the bright points
are analyzed within a continuous time random walk framework. Their
spatial and temporal scaling suggests that the observed motions are
the walks of imperfectly correlated tracers on a turbulent fluid flow
in the lanes between granular convection cells.
Title: Magnetic Footpoint Motions and Superdiffusion
Authors: Cadavid, C.; Lawrence, J.; Ruzmaikin, A.
Bibcode: 2001AGUSM..SP51B07C
Altcode:
In order to study the properties of the velocities of magnetic foot
points in the photosphere, we analyzed the dynamics of magnetic G-band
bright points (MBP's) from data obtained at the Swedish Vacuum Solar
Telescope. Almost universally, random walks and diffusion are studied by
looking at the square of the displacement of an average fluid element in
a given time. For normal diffusion the scaling exponent that describes
the relation of the mean squared displacement to the time has a value
of 1. However this approach is inadequate for the study of the observed
motions, since the magnetic features are stopped in their motion at
``traps'' in the intergranular lanes. Additionally we only have access
to a limited amount of data. A more reliable characterization of the
fluid motions is obtained from low statistical moments, such as the
square root, or lower, of the displacements. In this case the scaling
exponent is 1.4. The motions are therefore superdiffusive: faster
than normal but slower than purely fluid turbulence. This not only
reveals turbulent dynamics between convection cells on the Sun, but
also gives quantitative information on the coupling of magnetic fields
to the solar flows. In turn these superdiffusive motions can be used to
drive the footpoints of magnetic flux tubes in a model of chromospheric
heating. This is a more realistic approach than using Gaussian noise
to approximate the turbulence component to the velocity field.
Title: Rotation of CaII K-line Faculae in Solar Cycles 22 and 23
Authors: Chapman, G. A.; Lawrence, J. K.; Walton, S. R.
Bibcode: 2001AAS...198.7103C
Altcode: 2001BAAS...33Q.893C
We have examined the temporal behavior of CaII K-line faculae for
parts of solar cycles 22 and 23. The data are from photometric images
obtained at the San Fernando Observatory (SFO) using the Cartesian Full
Disk Telescope no. 1 (CFDT1). The images are 512 by 512 pixels, each
pixel being 5.12 arc-sec square. The bandpass of the K-line filter
is 1 nm. For the interval mid-1988 to mid-1996 (most of cycle 22)
we find an autocorrelation very much like that published in Chapman,
Cookson and Dobias (1997). At a lag of 150 to 160 days, the 27-day
rotational modulation disappears, reappearing later but at a different
phase. For the second interval, from mid-1996 to the end of 1999,
the autocorrelation shows the 27-day rotational modulation persisting
out to a lag of nearly one year. Lomb periodograms will be shown for
these data for several intervals and the results will be discussed. This
research has been partially supported by NSF Grant ATM-9912132 and NASA
Grant NAG5-7191. Reference: Chapman, G.A., Cookson, A.M. and Dobias,
J.J. 1997, Ap.J. 482, 541.
Title: Mesogranulation and Turbulence in Photospheric Flows
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.
Bibcode: 2001AGUSM..SP41C02L
Altcode:
Cellular flows are present in the solar photosphere at two
distinct size scales, 2 Mm and 4 Mm, with distinct characteristic
times. Simultaneously present in the flow is a non-cellular component,
with turbulent scaling properties between 1 Mm and 64 Mm, and containing
30 % of the flow energy. These results are obtained by means of wavelet
spectral analysis and modeling of vertical photospheric motions in
a 2-hour sequence of 120 SOHO/MDI, high resolution, Doppler images
near disk center. The wavelets permit detection of specific local flow
patterns corresponding to convection cells. Standard spectral techniques
have difficulty resolving mesogranules for three basic reasons: (1) the
mesogranules are near in scale to granules and weaker in velocity and
(2) they are hidden by overlying turbulence because (3) global basis
functions, such as Fourier waves or spherical harmonics, do not allow
attention to be paid to the local topologies that label cellular flows.
Title: Response to weak solar forcing in a general circulation model
of the atmosphere.
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
Bibcode: 2000BAAS...32R.832C
Altcode:
No abstract at ADS
Title: Random Walks of Magnetic Bright Points and Coronal Loop Heating
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibcode: 2000AAS...196.4903L
Altcode: 2000BAAS...32..750L
The random walks of small-scale ( ~ 0.2 arcsec) magnetic bright points
(MBPs) in the lanes between photospheric granules are anomalous. The
temporal growth of the q-th moment of the displacement r(t) is a
power law with exponent q γ (q)/2. For normal, Gaussian walks γ
(q)= 1 for all q. However, for the MBP walks on time scales <
45 minutes we find that γ (2)<1 and that γ (q) is a decreasing
function of q. Many viable models for the heating of coronal loops are
based on the additon of energy via twisting and braiding of magnetic
flux lines by the random motions of their footpoints. If the MBPs are
associated with such footpoints, then the statistics of their motions
are directly relevant to coronal heating. For example, a number of
models derive heating rates based on moments of the displacements and
include the standard assumption that γ = 1. However, this assumption
is wrong for MBPs, and the actual value of γ depends on exactly which
moment enters the expression. All such models are therefore subject to
modification. The result γ (2)<1 is a result of pauses in the MBP
walks on all time scales (''fractal time'') up to ~ 45 min. This implies
that the motions of an individual footpoint are not statistically
stationary. This in turn means that the injection of energy into a
given loop will be strongly variable and intermittent. This can be
related to observations of the details of variability in coronal loop
emissions, giving information on the locations of energy deposition and
on time scales of energy release. We thus hope to further constrain
acceptable heating models. This work was supported in part by NSF
Grant ATM-9628882.
Title: Response to Weak Solar Forcing in a General Circulation Model
of the Atmosphere
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
Bibcode: 2000SPD....3102117C
Altcode: 2000BAAS...32..832C
We study the effect of variable external forcing on a dynamical
system proposed by Lorenz as a simple general circulation model of
the atmosphere. When a strong annual cycle is included, numerical
exploration reveals the existence of a variety of multi-year climate
states, which fall into two basic types. In the space of external
forcing parameters, the different kinds of climate state are interleaved
in an intricate pattern at scales < 0.01. This is below the ~ 0.1
level of observed solar cycle irradiance variability which can thus
modulate the model climate state. If the solar cycle is accompanied
by a steady drift in forcing, it can produce periodic modulation
which appears, disappears and even reverses its phase. A parametric
drift by itself produces intervals of steady, but sometimes differing,
climates punctuated by intermittent bursts of variability. Different
forcing parameters for the Northern and Southern Hemispheres produce
different responses to variable forcing.
Title: Anomalous Diffusion of Solar Magnetic Elements
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
Bibcode: 1999ApJ...521..844C
Altcode:
The diffusion properties of photospheric bright points associated
with magnetic elements (magnetic bright points) in the granulation
network are analyzed. We find that the transport is subdiffusive
for times less than 20 minutes but normal for times larger than 25
minutes. The subdiffusive transport is caused by the walkers being
trapped at stagnation points in the intercellular pattern. We find
that the distribution of waiting times at the trap sites obeys a
truncated Lévy type (power-law) distribution. The fractal dimension
of the pattern of sites available to the random walk is less than 2
for the subdiffusive range and tends to 2 in the normal diffusion
range. We show how the continuous time random walk formalism can
give an analytical explanation of the observations. We simulate this
random walk by using a version of a phenomenological model of renewing
cells introduced originally for supergranules by Simon, Title, &
Weiss. We find that the traps that cause the subdiffusive transport
arise when the renewed convection cell pattern is neither fixed nor
totally uncorrelated from the old pattern, as required in Leighton's
model, but in some intermediate state between these extremes.
Title: Anomalous Diffusion of Solar Magnetic Elements
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
Bibcode: 1999AAS...194.5506C
Altcode: 1999BAAS...31..911C
The diffusion properties of photospheric bright points associated with
magnetic elements (MBP's) in the granulation network are analyzed. We
find that the transport is subdiffusive for times less than 20 minutes
but normal for times larger than 25 minutes. The subdiffusive transport
is caused by the walkers being trapped at stagnation points in the
intercellular pattern. We find that the distribution of waiting times at
the trap sites obeys a truncated Levy type (power law) distribution. The
fractal dimension of the pattern of sites available to the random
walk is less than 2 for the subdiffusive range and tends to 2 in the
normal diffusion range. We show how the continuous time random walk
formalism can give an analytical explanation of the observations. We
simulate this random walk by using a version of a phenomenological
model of renewing cells introduced originally for supergranules by
Simon, Title and Weiss (1995). We find that the traps which cause the
subdiffusive transport arise when the renewed convection cell pattern
is neither fixed nor is it totally uncorrelated from the old pattern
as required in Leighton's model, but in some intermediate state between
these extremes. (Work supported in part by NSF grant ATM-9628882).
Title: Scaling Universality Classes and Analysis of Solar Data
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibcode: 1999AAS...194.9301L
Altcode: 1999BAAS...31..988L
Many solar phenomena display a scaling symmetry associated with random
multiplicative cascades. Here a physical measure, initially uniform
on a spatial, temporal, or space-time set, is divided among subsets
according to randomly determined fractions. This division is repeated
on smaller and smaller sub-subsets, so that the resulting measure at
the smallest scale is given at any point by the product of a string of
random fractions comprising its fragmentation history. Such measures
are highly intermittent. They characterize such solar phenomena as the
spatial distribution of magnetic flux in an active region and the time
distribution of global X-ray emission. The probability distribution
functions (PDFs) governing the random fractions fall into universality
classes with robust properties (Hentschel 1994). For example, all
PDFs which allow for zero fractions lead to measures with local peaks
of unlimited strengths which are progressively less and less space
filling. The GOES-2 X-ray data belong to this class, which indicates
the presence of critical behavior associated with flares (Lu &
Hamilton 1991). We investigate a number of time series for the presence
or absence of this property. Multifractals in nature may fall into a
narrow universality class described by just 3 parameters (Schertzer, et
al. 1997). We find that at least some examples of active region magnetic
fields do indeed have the conjectured form. Further, we apply a causal
space-time version of this class of multiplicative cascade processes
to forecasting the evolution of solar velocity fields. This work was
supported in part by NSF grant ATM-9628882. Hentschel, H.G.E. 1994,
Phys. Rev. E, 50, 243. Lu, E.T. & Hamilton, R.J. 1991, ApJ, 380,
L89. Schertzer, D., Lovejoy, S., Schmitt, F., Chigirinskaya, Y. &
Marsan, D. 1997, Fractals, 5, 427.
Title: Characteristic Scales of Photospheric Flows and Their Magnetic
and Temperature Markers
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibcode: 1999ApJ...513..506L
Altcode:
We study the characteristic scales of quiet-Sun photospheric velocity
fields along with their temperature and magnetic markers in Doppler
images from the Michelson Doppler Imager aboard the SOHO satellite
(SOHO/MDI) in simultaneous, Doppler, magnetic, and intensity images
from the San Fernando Observatory and in full-disk magnetograms
and an intensity image from National Solar Observatory (Kitt
Peak). Wavelet flatness spectra show that velocity fluctuations are
normally distributed (Gaussian). This is often assumed in stochastic
models of turbulence but had not yet been verified observationally
for the Sun. Temperature fluctuations also are Gaussian distributed,
but magnetic fields are intermittent and are gathered into patterns
related to flow structures. Wavelet basis functions designed to detect
characteristic convection cell-flow topologies in acoustically filtered
SOHO/MDI Doppler images reveal granulation scales of 0.7-2.2 Mm and
supergranulation scales of 28-40 Mm. Mesogranular flows are weakly but
significantly detected in the range 4-8 Mm. The systematic flows account
for only 30% of the image variances at granular and supergranular
scales and much less in between. The main flows for the intermediate
range of 2-15 Mm are self-similar, i.e., chaotic or turbulent.
Title: Spatiotemporal Correlations and Turbulent Photospheric Flows
from SOHO/MDI Velocity Data
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.; Walton,
S. R.; Tarbell, T.
Bibcode: 1998ApJ...509..918C
Altcode:
Time series of high-resolution and full-disk velocity images obtained
with the Michelson Doppler Imager (MDI) instrument on board SOHO
have been used to calculate the spacetime spectrum of photospheric
velocity flow. The effects of different methods for filtering acoustic
oscillations have been carefully studied. It is found that the spectra
show contributions both from organized structures that have their origin
in the convection zone and from the turbulent flow. By considering
time series of different duration and cadence in solar regions with
different line-of-sight projections, it is possible to distinguish the
contributions of the spectra from the two different kinds of flows. The
spectra associated with the turbulent velocity fields obey power laws
characterized by two scaling parameters whose values can be used to
describe the type of diffusion. The first parameter is the spectral
exponent of the spatial correlation function and the second is a
scaling parameter of the time correlation function. Inclusion of the
time parameter is an essential difference between the present work
and other solar studies. Within the confidence limits of the data,
the values of the two parameters indicate that the turbulent part of
the flow in the scale range 16-120 Mm produces superdiffusive transport.
Title: NGST Yardstick Integrated Science Instrument Module (ISIM)
Feasibility Study
Authors: Greenhouse, M. A.; Dipirro, M.; Federline, B.; Gardner,
Jonathan P.; Guy, P.; Hagopian, J.; Hein, J.; Jurotich, M.; Lawrence,
J.; Martineau, B.; Mather, J. C.; Mentzell, E.; Satyapal, S.; Stanley,
D.; Teplitz, H. I.; Travis, J.; Bely, P.; Petro, L. D.; Stockman,
P.; Burg, R.; Bitzel, R.
Bibcode: 1998AAS...193.3504G
Altcode: 1998BAAS...30.1296G
We display portions of the baseline design concept for the NGST
Integrated Science Instrument Module (ISIM). This ISIM design is under
ongoing development for integration with the "Yardstick" and other
NGST 8 m architectures that are intended for packaging in an EELV or
Ariane 5 meter class fairing. The goals of this activity are to: [1]
demonstrate mission science feasibility, [2] identify ISIM technology
challenge areas, [3] assess ISIM engineering and cost feasibility,
[5] identify ISIM/NGST interface constraints, and [6] enable smart
customer procurement of the ISIM. In this poster, we display a snap
shot of work in progress including: optical design, opto-mechanical
layout, thermal modeling, focal plane array design, and electronics
design. Ongoing progress can be monitored via ISIM team web site:
http://ngst.gsfc.nasa.gov/
Title: Transient solar influence on terrestrial temperature
fluctuations
Authors: Lawrence, J. K.; Ruzmaikin, A. A.
Bibcode: 1998GeoRL..25..159L
Altcode:
We argue that the 11-year periodic solar cycle input assisted by
intrinsic climatic noise can produce transient correlations between
activity on the Sun and the Earth's temperature. The argument is based
on wavelet analysis of simultaneous, 140-year time series of terrestrial
global temperature and solar activity. It is supported by a simple model
utilizing the concept of “stochastic resonance,” a unique effect of
amplification of a weak, periodic signal by a noisy, nonlinear system.
Title: Scale Dependence of Photospheric Magnetic, Velocity and
Temperature Structure
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibcode: 1997SPD....28.0247L
Altcode: 1997BAAS...29..901L
Time series fluctuations may show different structure when observed
at different time scale resolutions. Thus, wavelet analysis reveals
that fluctuations in the International Sunspot Number are intermittent
(that is, distributed with kurtosis K>0) on scales less than 2 yr,
but truncated (K<0) on time scales between 2-8 yr. Terrestrial
temperature fluctuations are normally distributed (K=0) over discrete
timescale bands (<1 yr, 4-6 yr, 13 yr) interspersed by regimes of
intermittence (1-4 yr) and truncation (6-13 yr). Similar effects occur
for spatial phenomena. We employ various continuous, two-dimensional
wavelets to analyze digital solar images in Cartesian projection
(simultaneous, co-registered San Fernando Observatory magnetic,
Doppler and continuum images; SOHO/MDI high resolution Doppler images)
and full-disk images in hemispheric projection (KPNO magnetograms,
SOHO/MDI Doppler images). The temperature and velocity data are normally
distributed at all scales up to 64 arc sec, though the temperature
gradients are slightly intermittent (K~1). The magnetic data are mostly
intermittent. Wavelet power spectra for KPNO full-disk magnetograms
are quite featureless and indicate scale invariance of the magnetic
structures. Structural spectra of both active and quiet sun images,
however, show a strong peak in intermittence at a scale near 8 arc
sec. Wavelet analysis permits localization of structures in space as
well as in spatial scale. The highly intermittent structures can be
mapped and are found to be located not in active regions but in some,
though not all, areas of low magnetic activity. We discuss possible
physical relationships among the magnetic, velocity and temperature
distributions studied.
Title: Decorrelation Time of Fourier modes in the Spectrum of Solar
Background Velocity Fields
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
Bibcode: 1997SPD....28.0261C
Altcode: 1997BAAS...29..904C
We calculate the power-energy spectrum of time series of SOHO/MDI
line-of sight high resolution Doppler images near disk center. While the
spatial spectrum presents velocity features at characteristic scales and
not a cascade in wavenumber space, we investigate the extent to which
it is still possible to describe in terms of a scaling exponent the
properties of the decorrelation time for each Fourier mode as a function
of wavelength. We explore the sensitivity of the result to different
methods for removing the contribution of the p-modes to the spectrum.
Title: Wavelet and Multifractal Analyses of Spatial and Temporal
Solar Activity Variations
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibcode: 1997scma.conf..421L
Altcode:
No abstract at ADS
Title: Spectral Properties of Solar Convection and Diffusion
Authors: Ruzmaikin, A. A.; Cadavid, A. C.; Chapman, G. A.; Lawrence,
J. K.; Walton, S. R.
Bibcode: 1996ApJ...471.1022R
Altcode:
We present the results of a study of the scaling properties of
solar photo spheric motions. We use time series of Doppler images
obtained in good seeing conditions with the San Fernando Observatory
28 cm vacuum telescope and vacuum spectroheliograph in video
spectra-spectroheliograph mode. Sixty line-of- sight Doppler images of
an area of the quiet Sun near disk center are investigated. They were
taken at 60 s intervals over a 1 hr time span at ∼2" resolution. After filtering to remove 5 minute acoustic oscillations, the
time-spatial spectrum of the velocity is calculated. To study the
turbulence of photospheric flows in the mesogranulation scale range,
we estimate two scaling parameters in the spectrum: the exponent of
the spatial part of the power spectrum and the exponent governing the
scaling of time correlations of each spatial mode. These parameters
characterize the type of diffusion involved and the fractal dimension of
the diffusion front. Our results indicate that the turbulent diffusion
produced by motions in this scale range is not normal diffusion but
superdiffusion.
Title: On the Multifractal Distribution of Solar Magnetic Fields:
Erratum
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibcode: 1996ApJ...467..473L
Altcode:
Many studies have pointed out fractal and multifractal properties of
photospheric magnetic fields, but placing the various approaches into
context has proved difficult. Although fractal quantities are defined
mathematically in the asymptotic limit of infinite resolution, real
data cannot approach this limit. Instead, one must compute fractal
dimensions or multifractal spectra within a limited range at finite
scales. The consequent effects of this are explored by calculation
of fractal quantities in finite images generated from analytically
known measures and also from solar data. We find that theorems relating
asymptotic quantities need not hold for their finite counterparts, that
different definitions of fractal dimension that merge asymptotically
give different values at finite scales, and that apparently elementary
calculations of dimensions of simple fractals can lead to incorrect
results. We examine the limits of accuracy of multifractal spectra from
finite data and point out that a recent criticism of one approach to
such problems is incorrect.
Title: On the Multifractal Distribution of Solar Magnetic Fields
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibcode: 1996ApJ...465..425L
Altcode:
Many studies have pointed out fractal and multifractal properties of
photospheric magnetic fields, but placing the various approaches into
context has proved difficult. Although fractal quantities are defined
mathematically in the asymptotic limit of infinite resolution, real
data cannot approach this limit. Instead, one must compute fractal
dimensions or multifractal spectra within a limited range at finite
scales. The consequent effects of this are explored by calculation
of fractal quantities in finite images generated from analytically
known measures and also from solar data. We find that theorems relating
asymptotic quantities need not hold for their finite counterparts, that
different definitions of fractal dimension that merge asymptotically
give different values at finite scales, and that apparently elementary
calculations of dimensions of simple fractals can lead to incorrect
results. We examine the limits of accuracy of multifractal spectra from
finite data and point out that a recent criticism of one approach to
such problems is incorrect.
Title: Spectral Properties of the Solar Background Velocity Field
Authors: Cadavid, A. C.; Chapman, G. A.; Lawrence, J. K.; Ruzmaikin,
A. A.; Walton, S. R.
Bibcode: 1996AAS...188.3506C
Altcode: 1996BAAS...28Q.872C
We study the scaling properties of time series of Doppler images
obtained in good seeing conditions with the San Fernando Observatory
28 cm vacuum telescope and vacuum spectroheliograph in video
spectra-spectroheliograph mode. The images correspond to two areas
of quiet Sun near disk center taken at 60 second intervals from one
hour to six hour spans at ~ 2 arcsec resolution. After removal of 5
min acoustic oscillations the time-spatial spectrum of the velocity is
calculated. To study the turbulence of photospheric flows we estimate
two scaling parameters: the exponent of the spatial part of the power
spectrum and the exponent governing the scaling of time correlations
of each spatial mode. The implied diffusive behavior produced by the
solar convection in the mesogranulation scale range is discussed. This
includes characterization of the type of diffusion involved and the
fractal dimension of the diffusion front.
Title: Turbulent and Chaotic Dynamics Underlying Solar Magnetic
Variability
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibcode: 1995ApJ...455..366L
Altcode:
We examine the temporal scaling properties of solar magnetic activity
on timescales from days to decades. Because of more than 63,000
usable data points, we concentrate on the daily International Sunspot
Number. Some results have been checked with other data sets, primarily
the 10.7 cm microwave flux with about 16,000 data points. Such time
series provide a measure whose scaling and intermittency properties
are analyzed. By means of correlation analysis and both Fourier
and wavelet spectral analysis, we distinguish two regimes of temporal
behavior of the magnetic variability. The scaling of the time series is
analyzed in terms of multiplicative cascade processes which prove to
be invariant over more than two decades of scale from about 2 yr down
to about 2 days or less. We interpret this result to indicate generic
turbulent structuring of the magnetic fields as they rise through the
convection zone. We find that a low-dimensional, chaotic behavior in the
sunspot number operates entirely at timescales longer than a transition
threshold scale of about 8 yr. Magnetic variability on timescales
between 2 yr and 8 yr apparently requires handling by direct simulation.
Title: Features of the Solar Background Velocity Field
Authors: Ruzmaikin, A.; Cadavid, C.; Chanpman, G.; Lawrence, J.;
Walton, S.
Bibcode: 1995ESASP.376b.249R
Altcode: 1995help.confP.249R; 1995soho....2..249R
No abstract at ADS
Title: Turbulence and Chaos in Solar Variability
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
Bibcode: 1995SPD....26..514C
Altcode: 1995BAAS...27..960C
No abstract at ADS
Title: Multiplicative cascade models of multifractal solar magnetic
fields
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibcode: 1995PhRvE..51..316L
Altcode:
We present a multifractal analysis of digital, photoelectric images
of line-of-sight magnetic fields in solar active regions and quiet
photosphere. We study a positive definite measure related to the Ohmic
dissipation of magnetic energy. After calculation of the multifractal
spectrum directly and by scaling of the moments of the measure, we
focus on a multiplicative cascade approach. We infer a scale-invariant
rule by which the Ohmic dissipation measure is allocated among subsets
of its support through a hierarchy of scales. Knowledge of this rule,
which is hampered to some extent by image noise, permits the calculation
of the multifractal spectrum to great accuracy. The scaling of the
solar dissipation field resembles that of fully developed turbulence
in an atmospheric boundary layer. The cascade multiplier probability
distribution is itself a very useful quantity. It allows a convenient
display of image properties, such as self-similarity. Further, it is
more closely related than the multifractal spectrum to the physics
of the turbulent field evolution, and it thus can be used to impose
stronger constraints on turbulent dynamo models of magnetic field
generation.
Title: Spectra of Solar Magnetic Fields and Diffusion
Authors: Ruzmaikin, A. A.; Cadavid, A. C.; Chapman, G. A.; Lawrence,
J. K.; Walton, S. R.
Bibcode: 1995ASPC...76..292R
Altcode: 1995gong.conf..292R
No abstract at ADS
Title: Scaling of Solar Magnetic Fields
Authors: Ruzmaikin, A.; Cadavid, C.; Lawrence, J.; Rabin, D.; Lin,
H. -S.
Bibcode: 1995itsa.conf..375R
Altcode:
No abstract at ADS
Title: Multifractal Models of Small-Scale Solar Magnetic Fields
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.;
Kayleng-Knight, A.
Bibcode: 1994ApJ...429..391C
Altcode:
We generate, both analytically and numerically, artifical,
two-dimensional images composed of a known self-similar, and thus
multifractal measured with added Gaussian white noise. These are
used to interpret observed, line-of-sight, solar magnetic field
distributions noisy multifractals. The range of self-similar scaling of
observed, distributions is extended beyond that of previous work. Our
interpretation of the data is then used to confront theoretical models
for the generation of small-scale solar magnetic fields. We investigate
the multifractial structure of the field generated by two-dimensional,
random cell dynamos and find that self-similarity is relatively enhanced
for more intermittent distributions and strong correlations between
cells. An optimum value of the intercellular diffusion coefficient
maximizes the degree of intermittency. The simulated field from
a linear, kinematic, fast dynamo with two-dimensional, chaotic,
'ABC' flow displays scaling properties resembling those of observed
solar fields. We suggest that the chaotic element of this model is
the crucial ingredient for the long-range correlations that lead to
multifractal scaling.
Title: Scaling properties of photospheric magnetic fields
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibcode: 1994ASIC..433..279L
Altcode:
No abstract at ADS
Title: Multifractal Measure of the Solar Magnetic Field
Authors: Lawrence, J. K.; Ruzmaikin, A. A.; Cadavid, A. C.
Bibcode: 1993ApJ...417..805L
Altcode:
We analyze high-resolution, digital, photoelectric images of solar
photospheric magnetic fields. The line-of-sight fields are found to
scale in a self-similar way with resolution and thus can be expressed
in the form of a signed multifractal measure. The scaling properties of
the measure are used to extrapolate field integrals, such as moments of
the magnetic field, below resolvable limits. The scaling of the field
moments is characteristic of highly intermittent fields. We suggest
that the quiet-Sun photospheric fields are generated by local dynamo
action based on random convective motions at high magnetic Reynolds
number. The properties of active region images are determined by the
presence of fields generated by the global, mean field dynamo.
Title: Contrast of faculae near the disk center and solar variability
Authors: Lawrence, J. K.; Topka, K. P.; Jones, H. P.
Bibcode: 1993JGR....9818911L
Altcode:
We analyze simultaneous, or near-simultaneous, coregistered, digital,
photometric images of solar photospheric intensity and line-of-sight
magnetic field. Images were made with the Lockheed tunable filter
instrument at the Swedish Solar Observatory, La Palma, with the video
spectra-spectroheliograph system at the San Fernando Observatory and
with the new NASA spectromagnetograph at the National Solar Observatory
at Kitt Peak. We study the disk center contrasts of small magnetic
elements. While active region faculae are dark at disk center quiet
Sun network features are bright. The populations of magnetic field
elements that make up these two kinds of are quite different. Different
contrast center-limb functions must be used when estimating their
irradiance or luminosity contributions. The disk center contrasts of
active region faculae are color dependent and indicate a depth effect
related to the H- opacity of the facular atmosphere. This
result is important for calibration of monochromatic observations
of faculae to bolometric irradiance fluctuations. We emphasize the
value of cooperative observations among installations whose differing
strengths are complementary.
Title: Anomalous Diffusion of Magnetic Elements across the Solar
Surface
Authors: Lawrence, J. K.; Schrijver, C. J.
Bibcode: 1993ApJ...411..402L
Altcode:
Results are presented of observations of the random walks of
concentrations of magnetic flux on the solar surface, giving a natural,
macroscopic realization of anomalous diffusion with fractal dimension
D = 1.56 +/- 0.08 and exponent of anomalous diffusion theta = 0.25
+/- 0.40. The results indicate that the random walk of magnetic flux
in the solar photosphere is non-Euclidian and not two-dimensional
diffusion. The results are entirely consistent with results from
percolation theory for diffusion on clusters at a density below the
percolation threshold.
Title: Self-Similarity in Solar Magnetic Images
Authors: Lawrence, J. K.; Ruzmaikin, A. A.; Cadavid, A. C.
Bibcode: 1993BAAS...25.1219L
Altcode:
No abstract at ADS
Title: Multiscale Measure of the Solar Magnetic Field
Authors: Ruzmaikin, A. A.; Lawrence, J. K.; Cadavid, A. C.
Bibcode: 1993BAAS...25.1219R
Altcode:
No abstract at ADS
Title: Solar Magnetic Fields, Multifractals and Dynamos
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.;
Kayleng-Knight, A.
Bibcode: 1993BAAS...25R1206C
Altcode:
No abstract at ADS
Title: Inclination of the Magnetic Lines-of-Force of Quiet Sun Network
Authors: Topka, K. P.; Tarball, T. D.; Title, A. M.; Lawrence, J.
Bibcode: 1993AAS...182.4803T
Altcode: 1993BAAS...25R.879T
Photometric measurements of the continuum contrast of active region
plage, after carefully removing all sunspots and pores, has been
obtained for several years from the Swedish Solar Observatory, La
Palma. More recently, similar measurements have been obtained for
magnetic elements in the network far from active regions. These data
were taken with the Lockheed tunable filter instrument using a CCD
camera. The measurements indicate that at disk center active region
plage is dark (negative contrast: intensity less than the surrounding
quiet sun), while the network is bright. Furthermore, active region
plage rapidly turns bright toward the limb; the network also brightens
but more slowly. We have constructed a simple model that assumes
that the magnetic lines-of-force are approximately vertical in active
region plage, while those in the quiet sun network are inclined at the
photosphere. This model correctly predicts the continuum contrast of
network at disk center, and also its variation from center-to-limb. This
provides evidence that the network is often inclined from vertical by
30 degrees or more. This work was supported by Lockheed IR Funds, by
NASA contracts NAS8-32805 (SOUP), NAS5-26813 (OSL), NAS5-30386 (MDI),
and NAS8-38106 (BSOUP), and NSF contract ATM-8912841.
Title: Photometric Measurements of Sunspots Deficits and Facular
Excesses
Authors: Chapman, G. A.; Lawrence, J. K.; Hudson, H. S.
Bibcode: 1992sers.conf..135C
Altcode:
No abstract at ADS
Title: Precise ground-based solar photometry and variations of
total irradiance
Authors: Chapman, G. A.; Herzog, A. D.; Lawrence, J. K.; Walton,
S. R.; Hudson, H. S.; Fisher, B. M.
Bibcode: 1992JGR....97.8211C
Altcode:
Variations in the total solar irradiance measured by the active cavity
radiometer irradiance monitor (ACRIM) on SMM have been correlated
with measures of magnetic activity on the solar disk. Quantitative
indices of magnetic activity were derived from ground-based, full-disk,
photometric images of the Sun at red (6723 Å) and violet (3934-Å K
line) wavelengths. The red images have been obtained on a daily basis
at the San Fernando Observatory since 1985, and the K line images
since 1988. Sunspot irradiance deficits are calculated directly
from the red images while proxy measures of facular irradiance
excesses are derived from the K line images. The images analyzed
here were made during 21 days between June 20 and July 14, 1988,
a period centered on the disk passage of a large sunspot group. The
best two-parameter multiple correlation coefficient between the
ACRIM data and the photometric data is R2=0.97 (21 data
points, 18 degrees of freedom). The zero point S0=1367.27
W m-2 agrees well with the solar irradiance
measured by ACRIM/SMM during the 1986 activity minimum: the residual
standard deviation was 0.13 W m-2 (about 100
ppm). The multiple correlations were extended to include measures
of the irradiance contribution of ``network'' magnetic fields,
unassociated with active regions. NOAA 9 spacecraft observations of UV
MgII lines at 2800 Å gave R2=0.99 (17 degrees of freedom)
with S0=1366.68+0.08 W m-2. The index of 10.7-cm
microwave flux gave R2=0.98, with S0=1366.43+0.11
W m-2. We can thus model short-term irradiance
changes to within 100 ppm relative precision from ground-based data.
Title: Patterns in the photospheric magnetic field and percolation
theory
Authors: Schrijver, C. J.; Zwaan, C.; Balke, A. C.; Tarbell, T. D.;
Lawrence, J. K.
Bibcode: 1992A&A...253L...1S
Altcode:
The magnetic field in solar plages forms a highly structured pattern
with no apparent characteristic length scale. This pattern appears
to be a fractal with a dimension between 1.45 and 1.60. Small-scale
displacements of concentrations of magnetic flux in the network
are consistent with a random walk on a fractal with a similar
dimension. Percolation theory offers an effective explanation for
observed geometric properties of small-scale flux concentrations
in the solar photosphere, by demonstrating the close correspondence
with clusters formed by randomly placed tracers on a 2D (irregular)
lattice. Percolation theory also offers a model for the subdiffusive
behavior of tracers performing a random walk on clusters formed
by bonded sites. The geometry of flux concentrations and of the
displacement of magnetic flux as a function of time are equivalent
to situations in percolation theory below a critical value, called
'the percolation threshold'.
Title: Fractals in Magnetograms
Authors: Schrijver, C. J.; Zwaan, C.; Balke, A. C.; Tarbell, T. D.;
Lawrence, J. K.
Bibcode: 1992ASPC...27...67S
Altcode: 1992socy.work...67S
No abstract at ADS
Title: The Effect of Fractal Distribution on the Evolution of Solar
Surface Magnetic Fields
Authors: Lawrence, J. K.; Schrijver, C. J.
Bibcode: 1992ASPC...27...48L
Altcode: 1992socy.work...48L
No abstract at ADS
Title: Diffusion of magnetic flux elements on a fractal geometry
Authors: Lawrence, J. K.
Bibcode: 1991SoPh..135..249L
Altcode:
Recent observations have indicated that magnetic field elements
are distributed on the Sun in fractal patterns with dimension D
< 2. We suggest that the transport of magnetic field elements
across the solar surface should be treated as diffusion on a fractal
geometry. We review a semi-analytical, theoretical treatment of fractal
diffusion. Comparison with observations of small-scale motions of solar
magnetic flux concentrations indicates that fractal diffusion may be
taking place with dimension in the range 1.3 to 1.8. It is shown that,
compared to the predictions that would be made for two-dimensional
diffusion, fractal diffusion in this range would lead to an increased
level of in situ flux cancellation in decaying active regions by 7%
to 35%. Other work in specialities outside of solar physics may be
useful in explaining solar magnetic phenomena.
Title: Weak Magnetic Fields and Solar Irradiance Variations
Authors: Lawrence, J. K.; Chapman, G. A.; Walton, S. R.
Bibcode: 1991ApJ...375..771L
Altcode:
NOAA active region 5643 was observed from August 17 to 21, 1989. Sets
of video spectra-spectroheliograms including the Fe I line at 6302.5
A were made at least daily with the San Fernando Observatory 28 cm
vacuum telescope and vacuum spectroheliograph. These give simultaneous,
co-registered digital images representing monochromatic continuum
intensity, line core intensity and line-of-sight magnetic field. Three
different criteria are used to define the pixels representing the
quiet sun and the facular portions of the images. These criteria
are the magnetic field strength, the line core intensity, and the
distribution of continuum intensities. Each of these definition schemes
is used to estimate the irradiance change due to facular emission. The
magnetic field and the continuum intensity distribution definitions
give estimates which agree closely. The line core intensity definition
leads to larger estimates of the facular irradiance contribution. Some
model-dependent investigations of the contrasts and sizes of individual
facular elements also are presented.
Title: Total Solar Irradiance Variations Compared with Ground-Based
Photometry at the SFO
Authors: Chapman, G. A.; Lawrence, J. K.; Hudson, H. S.
Bibcode: 1991BAAS...23.1067C
Altcode:
No abstract at ADS
Title: Ground-Based Modelling of Solar Irradiance Variations
Authors: Lawrence, J. K.; Chapman, G. A.; Herzog, A. D.; Walton,
S. R.; Hudson, H. S.; Fisher, B. M.
Bibcode: 1991BAAS...23..960L
Altcode:
No abstract at ADS
Title: Continuum Contrast and Center to Limb Variation of Solar
Magnetic Elements Observed in the Photosphere
Authors: Swearingen, D. J.; Walton, S. R.; Chapman, G. A.; Lawrence,
J. K.
Bibcode: 1991BAAS...23..960S
Altcode:
No abstract at ADS
Title: Photometric Observations of the Energetics of Small Solar
Active Regions
Authors: Lawrence, J. K.; Chapman, G. A.
Bibcode: 1990ApJ...361..709L
Altcode:
The energetics of small solar active regions was investigated using
for the analysis the photometric solar images taken from July 29 to
September 6, 1984 with the San Fernando Observatory's 28-cm vacuum
telescope, vacuum spectroheliograph, and dual 512 element Reticon
linear diode arrays. Ten small newly formed regions were observed,
whose entire sunspot evolution apparently occurred within the observed
disk crossing. Seven of these showed a net energy excess of a few times
10 to the 33th ergs during this time. These results are discussed in
connection with the 0.1 percent decline in solar irradiance observed
by the SMM/ACRIM and Nimbus 7/ERB radiometers between 1980 and 1986.
Title: Diffusion of Solar Magnetic Flux Elements on Fractals
Authors: Lawrence, J. K.
Bibcode: 1990BAAS...22.1233L
Altcode:
No abstract at ADS
Title: A program of photometric measurements of solar irradiance
fluctuations from ground-based observations.
Authors: Chapman, G. A.; Herzog, A. D.; Lawrence, J. K.; Walton, S. R.
Bibcode: 1990NASCP3086...16C
Altcode: 1990cisv.nasa...16C
Photometric observations of the sun have been carried out at the
San Fernando Observatory since early 1985. Since 1986, observations
have been obtained at two wavelengths in order to separately measure
the contributions of sunspots and bright facular to solar irradiance
variations. The authors believe that the contributions of sunspots can
be measured to an accuracy of about ±30 ppm. The effect of faculae is
much less certain, with uncertainties in the range of ±300 ppm. The
larger uncertainty for faculae reflects both the greater difficulty
in measuring the facular area, due to their lower contrast compared
to sunspots, and the greater uncertainty in their contrast variation
with viewing angle on the solar disk. Recent results from two separate
photometric telescopes will be compared with bolometric observations
from the ACRIM that was on board the Solar Max satellite.
Title: Solar Variability Measured by SMM/ACRIM Compared with
Ground-Based Photometry
Authors: Chapman, G. A.; Herzog, A. D.; Lawrence, J. K.; Walton,
S. R.; Hudson, H. S.; Fisher, B.
Bibcode: 1990BAAS...22..897C
Altcode:
No abstract at ADS
Title: Continuum Contrast of Photospheric Faculae Compared to their
Magnetic Flux
Authors: Lawrence, J. K.; Chapman, G. A.; Walton, S. R.
Bibcode: 1990BAAS...22..839L
Altcode:
No abstract at ADS
Title: Self-Ordering of Photospheric Magnetic Fields
Authors: Lawrence, J. K.
Bibcode: 1990IAUS..138..383L
Altcode:
No abstract at ADS
Title: Photometric Observations of Net Energy Excesses in Small
Solar Active Regions
Authors: Lawrence, J. K.; Chapman, G. A.; Herzog, A. D.
Bibcode: 1989BAAS...21.1179L
Altcode:
No abstract at ADS
Title: Photometric Measurements of Solar Irradiance Variations Due
to Sunspots
Authors: Chapman, G. A.; Herzog, A. D.; Laico, D. E.; Lawrence, J. K.;
Templer, M. S.
Bibcode: 1989ApJ...343..547C
Altcode:
A photometric telescope constructed to obtain photometric sunspot areas
and deficits on a daily basis is described. Data from this Cartesian
full disk telescope (CFDT) are analyzed with attention given to the
period between June 4 and June 17, 1985 because of the availability
of overlapping sunspot area and irradiance deficit data from
high-resolution digital spectroheliograms made with the San Fernando
Observatory 28 cm vacuum solar telescope and spectroheliograph. The
CFDT sunspot deficits suggest a substantial irradiance contribution
from faculae and active region plage.
Title: Photometric Observations of Facular Contrasts near the
Solar Limb
Authors: Lawrence, J. K.; Chapman, G. A.
Bibcode: 1988ApJ...335..996L
Altcode:
Digital, photometric images of several active regions near the solar
limb made with 1.5 A effective bandpass at 6264 A are analyzed. From
three to ten images were made per day on several days during 1983, 1984,
and 1987 with the San Fernando Observatory 28 cm vacuum solar telescope
and spectroheliograph and 512 element Reticon linear diode arrays. Pixel
spacing is 0.94 arcsec. Pixels in each image were sorted into quiet sun
and facular intensity distributions by mu value, where mu = cos theta
and theta is the heliocentric angle between the pixel and the direction
of earth. These distributions were converted to overall average values
of facular pixel contrast relative to the quiet sun background by mu
value, and a center-limb variation of contrast per facular element was
derived. If one is careful to distinguish between contrasts per unit
projected area (pixel contrasts) and contrasts per facular element
or individual flux tube, the results are in reasonable agreement with
those of other workers. The center-limb contrast variation resembles a
'hot wall' model of facular emission, with indications of an additional
emitting component which protrudes above the photospheric level.
Title: Multi-Color Photometric Observations of Facular Contrasts
Authors: Lawrence, John K.
Bibcode: 1988SoPh..116...17L
Altcode:
We have analyzed high-resolution, digital, photometric images of solar
active regions made at various center-limb positions on 21-24 July,
1983. The images were made at three continuum wavelengths: 5245 Å in
the green (bandpass 1.5 Å), 6264 Å in the red (bandpass 1.5 Å),
10 000 Å in the infrared (bandpass 3 Å), and also at 8662 Å in
the CaII infrared line (bandpass 3 Å). In all continuum colors, the
contrasts of facular patches, as opposed to individual facular elements,
appear to behave as linear functions of 1/cos θ, where θ is the
heliocentric angle (μ = 0 at the limb, 1 at disk center). The relative
contrasts in the different continuum colors are roughly proportional to
(wavelength)-1, as expected from a Planck distributioin in
the Wien approximation. The observed variation of the relative contrasts
with center-limb position is compared to two simple theoretical models.
Title: Photometric Determination of Facular Contrasts near the Solar
Disk Center
Authors: Lawrence, J. K.; Chapman, G. A.; Herzog, A. D.
Bibcode: 1988ApJ...324.1184L
Altcode:
The authors have analyzed pairs of simultaneous, co-registered, digital,
photometric images of several solar active regions made with 3 Å
effective bandpasses in the Ca II line at 8662 Å and in the nearby
clean continuum at 8642 or 8682 Å. From these data the authors derive a
continuum facular contrast at disk center of 0.74%±0.11%. This contrast
remains roughly constant from disk center to r = 0.45 R_sun; before
increasing. These results lead to an increase of 10% - 20% in earlier
estimates of facular contributions to solar luminosity fluctuations,
which were found to be 70% - 120% of the sunspot contributions.
Title: Color Dependence of Facular Contrasts
Authors: Lawrence, J.
Bibcode: 1988srov.proc..310L
Altcode:
No abstract at ADS
Title: Photometric Facular Contrasts Near the Extreme Solar Limb
Authors: Lawrence, J. K.; Chapman, G. A.
Bibcode: 1987BAAS...19R1132L
Altcode:
No abstract at ADS
Title: Photometric Measurements of Facular Contrasts near the Solar
Disk Center
Authors: Lawrence, J. K.
Bibcode: 1987BAAS...19..924L
Altcode:
No abstract at ADS
Title: Sunspot Cycle Variations of Ensemble-Averaged Active Regions
Authors: Lawrence, John K.
Bibcode: 1987SoPh..110...73L
Altcode:
We examine published sunspot and calcium plage areas for 1620 solar
active regions between 1974 and 1985. With these data we study the
properties of ensemble-averaged active regions. The average sunspot area
per region, the average plage to sunspot area ratio, and the average
plage intensity of regions all vary significantly with the sunspot
cycle and in correlation with one another. The average plage area
per region varies significantly but is uncorrelated with the sunspot
cycle and with the other quantities. While the plage and sunspot areas
and the plage intensities of individual active regions observed over
a two-year period are strongly correlated, the relationship among
these quantities appears to change over an 11-yr period. These results
suggest the existence of some energetic connection between active region
sunspot areas and plage intensities. Further, if energy balance between
sunspot luminosity deficits and facular luminosity excesses holds,
then standard models relating these quantities to sunspot and plage
areas will have to be modified. Overall energy balance can neither be
established nor ruled out.
Title: Ratio of calcium plage to sunspot areas of solar active
regions.
Authors: Lawrence, J. K.
Bibcode: 1987JGR....92..813L
Altcode:
Published sunspot and calcium plage areas were examined for about 1,700
solar active regions (ARs) between 1971 and 1982. With these data,
averaged AR properties, the possibility of energy balance between
spot and facular emission over the lifetimes of activity complexes,
and changes in AR properties over an 11-year sunspot cycle were
studied. Overall energy balance can neither be established nor ruled
out. Apparently, real temporal changes in the nature of ARs, however,
imply either that energy balance cannot hold over periods shorter
than a few years or that standard models for estimating irradiance
fluctuations from spot and/or plage areas must be modified.
Title: Facular Contrasts from High-Resolution Photometric Images
Authors: Lawrence, J. K.; Herzog, A. D.
Bibcode: 1986BAAS...18..932L
Altcode:
No abstract at ADS
Title: Time-integrated energy budget of a solar activity complex
Authors: Chapman, G. A.; Herzog, A. D.; Lawrence, J. K.
Bibcode: 1986Natur.319..654C
Altcode:
The 0.1-0.3% dips in solar irradiance during disk passages of large
sunspot groups suggest the possibility of fluctuations in the solar
luminosity. This raises the question of whether the energy not radiated
by the dark sunspots is stored within the Sun for long periods of
time, or is radiated by faculae during the several-month lifetime of
a solar activity complex1-3. Here we examine the sunspot
and facular contributions to luminosity fluctuations due to a solar
activity complex over its lifetime from June to November 1982. Both
direct, photometric observations of irradiance fluctuations and modelled
`proxy' fluctuations based on published sunspot and calcium plage areas
are used. We find that the total facular energy excess is between 70 and
120% of the sunspot deficit of ~1037 erg. Thus, at a minimum,
a major portion of the missing sunspot flux is radiated by faculae, and
energy balance or even an excess is possible. This work differs from
earlier studies2-9 in that our data cover a longer period
of time, more photometric data are included, and our analysis considers
the effect of partial occultation of active regions by the solar limb.
Title: The Rotating Full Disk Reticon Photometer at the San Fernando
Observatory
Authors: Herzog, A. D.; Chapman, G. A.; Lawrence, J. K.; Templer, S.
Bibcode: 1985BAAS...17..833H
Altcode:
No abstract at ADS
Title: Ratio of Calcium Plage to Sunspot Area of Solar Active Regions
Authors: Lawrence, J. K.
Bibcode: 1985BAAS...17R.895L
Altcode:
No abstract at ADS
Title: Solar luminosity fluctuations during the disk transit of an
active region
Authors: Lawrence, J. K.; Chapman, G. A.; Herzog, A. D.; Shelton, J. C.
Bibcode: 1985ApJ...292..297L
Altcode:
Monochromatic, photometric observations, obtained with a 512 element
linear diode array, of the solar irradiance fluctuations caused
by an active region during its entire disk transit in 1982 August
are presented. Different methods of data analysis are described and
interrelated. The maximum sunspot fluctuation, as a fraction of quiet
sun irradiance, is about -800 parts per million (ppm). Faculae have a
maximum irradiance fluctuation of about +200 ppm. By integrating over
the viewing angle during disk transit it was possible to determine
that, for visible wavelengths, the facular luminosity excess is about
50 percent of the sunspot luminosity deficit. These results indicate
that faculae are an important element in active-region energetics. The
effects of stray light and bolometric corrections are also discussed.
Title: The Correlation of Solar Flare Production with Magnetic Energy
in Active Regions
Authors: Mayfield, E. B.; Lawrence, J. K.
Bibcode: 1985SoPh...96..293M
Altcode:
An investigation of 531 active regions was made to determine the
correlation between energy released by flares and the available
energy in magnetic fields of the regions. Regions with magnetic flux
greater than 1021 maxwell during the years 1967-1969, which
included sunspot maximum, were selected for the investigation. A linear
regression analysis of flare production on magnetic flux showed that
the flare energy is correlated with magnetic energy with a coeificient
of correlation of 0.78. Magnetic classification and field configuration
also significantly affect the production of flares.
Title: On the Possibility of Energy Balance Over the Lifetime of a
Solar Activity Complex
Authors: Lawrence, J. K.; Chapman, G. A.; Herzog, A. D.
Bibcode: 1985BAAS...17..610L
Altcode:
No abstract at ADS
Title: Observations concerning energy balance in solar magnetic
regions.
Authors: Chapman, G. A.; Herzog, A. D.; Lawrence, J. K.
Bibcode: 1984ESASP.220..241C
Altcode: 1984ESPM....4..241C
Variations in the solar irradiance detected by the Solar Maximum
Mission satellite have shown that sunspots alter the flow of heat near
the photosphere. Analysis of these observations suggest (1) that there
is storage of energy in active regions and (2) a significant fraction
(over one-half) of this stored energy is radiated from magnetic elements
(faculae) of the active region.
Title: Magnetic Field Inclination and the Double Return Flux
Sunspot Model
Authors: Lawrence, J. K.; Zhu, M.
Bibcode: 1984BAAS...16..979L
Altcode:
No abstract at ADS
Title: Observations Concerning the Energy Budget of a Solar Activity
Complex
Authors: Chapman, G. A.; Herzog, A. D.; Lawrence, J. K.; Shelton, J. C.
Bibcode: 1984BAAS...16..991C
Altcode:
No abstract at ADS
Title: Preliminary Analysis of Multi-color Reticon Data at the San
Fernando Observatory
Authors: Herzog, A. D.; Mason, S. F.; Chapman, G. A.; Lawrence, J. K.
Bibcode: 1984BAAS...16.1001H
Altcode:
No abstract at ADS
Title: Solar luminosity fluctuations and active region photometry
Authors: Chapman, G. A.; Herzog, A. D.; Lawrence, J. K.; Shelton, J. C.
Bibcode: 1984ApJ...282L..99C
Altcode:
Monochromatic observations, obtained with a 512-element diode array,
of the irradiance fluctuations of the sunspots and faculae of an active
region during its disk transit in August 1982 are presented. Bolometric
and stray light corrections are approximately equal in magnitude but
opposite in sign, so they have not been applied. The maximum sunspot
fluctuation, as a fraction of the quiet-sun irradiance, is -800 parts
per million (ppm). Faculae have a maximum irradiance fluctuation of
about +200 ppm near the limbs. It is found that the facular energy
excess is more than 50 percent of the sunspot energy deficit, which
is -5.8 x 10 to the 35th ergs. These observations show that faculae
are an important element in active region energy balance.
Title: Preliminary Observations on the Energy Budget of a Solar
Activity Complex, July-Sept. 1982
Authors: Chapman, G. A.; Herzog, A. D.; Lawrence, J. K.; Eskenas,
Kim; Mallory, Carolyn; Shelton, J. C.
Bibcode: 1984BAAS...16..729C
Altcode:
No abstract at ADS
Title: Two-dimensional photometry of active regions.
Authors: Lawrence, J. K.; Chapman, G. A.; Herzog, A. D.; Shelton, J. C.
Bibcode: 1984NASCP2310...91L
Altcode: 1984siva.work...91L
The authors describe a set of two-dimensional photometric images
of solar active regions (AR's). Preliminary analysis of the data is
described, and estimates are presented of the contribution of an AR to
total solar irradiance variations during its 1982 August 3 - 16 disk
passage. Results indicate an excess contribution near the limb and a
deficit away from the limb.
Title: Tests of Magnetohydrodynamics in Solar Active Regions
Authors: Lawrence, J. K.
Bibcode: 1984BAAS...16..528L
Altcode:
No abstract at ADS
Title: Properties of flares observed in the Mg i b2
line at 5172 Å
Authors: Lawrence, J. K.; Chapman, G. A.; Herzog, A. D.
Bibcode: 1983SoPh...89..341L
Altcode:
Observations of emission in the MgI b2 line at 5172 Å are
presented for 13 flares. Also discussed are 3 flares which occurred in
regions under observation but which showed no Mg emission. The Mg flare
kernels resemble white-light flare kernels in their general morphology
and location. Comparison of Mg filtergrams with magnetograms indicates
that the Mg kernels occur at the feet of magnetic arches across neutral
lines. Time-lapse Mg filtergram films indicate photospheric shearing
motions near flare sites for several hours before flare onset.
Title: Elaboration of the New Magnetohydrostatic Sunspot Theory -
Double Return Flux Model
Authors: Osherovich, V. A.; Lawrence, J. K.
Bibcode: 1983SoPh...88..117O
Altcode:
An extension of the recently formulated Return Flux Sunspot Model
is presented. The basic equation for a Double Return Flux Sunspot
Model is derived, and a pressure distribution and magnetic field
are calculated. The possible topology of the magnetic structure and
its thermodynamic consequences are discussed. The paper includes a
magnetogram of a single round sunspot (9 August, 1981). The authors
attempt to interpret the observational data for the vertical component
of magnetic field of this sunspot on the basis of the Double Return
Flux Model.
Title: Stray Light Corrections in Two-Dimensional Solar Photometry
Authors: Lawrence, J. K.; Chapman, G. A.; Herzog, A. D.; Shelton, J. C.
Bibcode: 1983BAAS...15..951L
Altcode:
No abstract at ADS
Title: Irradiance Measurement of Big Bear Active Region #511
Authors: Herzog, A. D.; Chapman, G. A.; Lawrence, J. K.; Shelton, J. C.
Bibcode: 1983BAAS...15R.973H
Altcode:
No abstract at ADS
Title: Observed Energy Balance of Active Region 18511, August 1982
Authors: Chapman, G. A.; Herzog, A. D.; Lawrence, J. K.; Shelton, J. C.
Bibcode: 1983BAAS...15..950C
Altcode:
No abstract at ADS
Title: The spatial distribution of umbral dots and granules.
Authors: Lawrence, J. K.
Bibcode: 1983SoPh...87....1L
Altcode:
A statistical analysis is made of the spatial distribution of umbral
dots and photospheric granules. The dots and granules are more evenly
spaced than random points, though dots mapped by different observers
have different distributions.
Title: Two-Dimensional Photometry of Active Region BBSO No. 18511
Authors: Chapman, G. A.; Herzog, A. D.; Lawrence, J. K.; Shelton, J. C.
Bibcode: 1983BAAS...15R.717C
Altcode:
No abstract at ADS
Title: Properties of Flares Observed in the MgI b2 Line at 5172 A
Authors: Lawrence, J. K.; Chapman, G. A.; Herzog, A. D.
Bibcode: 1983BAAS...15..697L
Altcode:
No abstract at ADS
Title: Ultramafic rock/seawater interaction in the oceanic crust:
Mg-silicate (sepiolite) deposit from the Indian Ocean floor
Authors: Bonatti, E.; Craig Simmons, E.; Breger, D.; Hamlyn, P. R.;
Lawrence, J.
Bibcode: 1983E&PSL..62..229B
Altcode:
A deposit consisting almost exclusively of the Mg-silicate sepiolite
has been sampled from the Owen transform zone in the western
Indian Ocean. This deposit is associated with basaltic, gabbroic
and ultramafic rocks. On the basis of major, trace and rare earth
elemental composition, strontium and oxygen isotopic ratios, as well
as of theoretical considerations, the sepiolite deposit appears to
have formed neither from seawater nor from solutions resulting from
the interaction of seawater with the basaltic crust. Interaction of
ultramafic rocks with seawater circulating in the crust, particularly
in transform zones, may produce solutions which at low temperature
(<100°C) become enriched in Mg and/or Si, and can give rise to
precipitation of sepiolite on or below the sea floor. The ratio
of Mg to Si in the solutions is probably a factor in determining
whether sepiolite or another Mg-silicate (i.e., one of the serpentine
polymorphs) is deposited.
Title: Active Region Photometry and Solar Variability
Authors: Chapman, G. A.; Groisman, G.; Herzog, A. D.; Lawrence, J. K.;
Meyer, A. D.; Shelton, J. C.
Bibcode: 1982BAAS...14..865C
Altcode:
No abstract at ADS
Title: Observations of Solar Flare Emission in the MgIb2
Line at 5172 A
Authors: Lawrence, J. K.; Chapman, G. A.; Herzog, A. D.
Bibcode: 1982BAAS...14..898L
Altcode:
No abstract at ADS
Title: Observations of Small Magnetic Features in Sunspots and
Active Regions
Authors: Lawrence, J. K.
Bibcode: 1981BAAS...13Q.882L
Altcode:
No abstract at ADS
Title: Magnetic features in active regions
Authors: Lawrence, J. K.; Thorman, S. C.
Bibcode: 1981phss.conf...75L
Altcode:
A program is described for studying the evolution of sunspot groups
by observing the motions of small magnetic features in evolving
active regions. The magnetic features are identified with small (less
than about 1.5 arcsec) bright points in magnesium filtergrams. The
filtergrams are made at intervals of 15s to 2m for several hours on
successive days during the evolution of sunspot groups and combined
with polarity information supplied by daily magnetograms. Results are
presented for a brief observing period on 22 June 1980. These indicate
lifetime of the bright features of 1 - 1.5 hr and transverse velocities
up to about 0.5 Km/s. More extensive observations are being carried
out at San Fernando Observatory during summer 1981.
Title: Magnetic field evolution observed in conjunction with SMM,
19 - 26 June 1980.
Authors: Chapman, G. A.; Thorman, S. C.; Lawrence, J. K.
Bibcode: 1981BAAS...13..491C
Altcode:
No abstract at ADS
Title: Gravitational focusing by a slowly rotating, relativistic,
spherical mass
Authors: Lawrence, J. K.
Bibcode: 1980ApJ...239..305L
Altcode:
Null rays emitted inside a relativistic, spherical mass can, depending
on the location of the emission point, emerge in highly focused
patterns. In order to increase the realism of this result, slow
rotation of the mass is allowed. The effect of this on the focusing
is complex and variable. Depending on the location of the emission
point, the effect of the rotation may be nil, the beam direction may be
shifted in the direction of the rotation, the radiation pattern may be
stretched in the direction opposite to the rotation, or the beams may
be defocused by an amount proportional to the specific angular momentum.
Title: Gravitational Lenses and the Double Quasar
Authors: Lawrence, J. K.
Bibcode: 1980Mercu...9...66L
Altcode:
No abstract at ADS
Title: Gravitational deflection of null radiation by relativistic,
spherical masses.
Authors: Lawrence, J. K.
Bibcode: 1979ApJ...230..249L
Altcode:
We consider bursts of null radiation emitted from point sources
at rest within a relativistic, spherical mass distribution whose
gravitational field is represented by the interior and exterior
Schwarzschild metrics. Numerical calculations are presented, in the
geometrical optics approximation, of the resulting distributions of
energy radiated to infinity. It is found that gravitational 'focal
points' exist within the mass in analogy with the external focal points
discussed earlier in the weak-field case. The possible relevance of
the present model to emission of null radiation by neutron stars,
active galaxies, and quasars is discussed.
Title: The future history of the universe.
Authors: Lawrence, J. K.
Bibcode: 1978Mercu...7..132L
Altcode:
No abstract at ADS
Title: Views of the universe over cosmological time spans
Authors: Lawrence, J. K.
Bibcode: 1977AmJPh..45.1164L
Altcode:
We consider an Earth observer's view of the universe as it would appear
at various stages of its evolution. This is calculated numerically
from the relativistic Friedmann universe models and is presented in
the form of Hubble plots of red shift versus distance for distant
galaxies. Trajectories of particular galaxies followed through time
are also shown. In the case of a closed universe, the results are
particularly complex and interesting.
Title: Trapped null geodesics in a rotating interior metric.
Authors: Collas, P.; Lawrence, J. K.
Bibcode: 1976GReGr...7..715C
Altcode:
We consider trapped, null geodesies in an interior, rotating metric
which matches the Kerr metric on a spheroidal surface. The interior
metric is unphysical, but still useful for obtaining a qualitative
understandng of the properties of the trapped, interior geodesies. We
find, by numerical techniques, that the presence of rotation increases
trapping for count-errotating orbits, but decreases it for corotating
orbits.
Title: Boundary conditions in closed universes.
Authors: Lawrence, J. K.
Bibcode: 1975GReGr...6..253L
Altcode:
We consider the problem of a particle in a square potential well in
a one-dimensional closed universe. Imposition of periodic boundary
conditions on the wave function changes the usual discrete energy
levels to narrow but finite energy bands. Effects on the properties
of atoms in a closed universe are estimated to be undetectable.
Title: Statistical physics, particle masses and the cosmological
coincidences
Authors: Lawrence, J. K.; Szamosi, G.
Bibcode: 1974Natur.252..538L
Altcode:
A new look at some familiar `cosmological coincidences' provides a means
of `predicting' appropriate mass values for the elementary particles.
Title: Strong interactions, gravitation and cosmology.
Authors: Salam, A.; Lawrence, J. K.
Bibcode: 1974hear.conf..441S
Altcode:
No abstract at ADS
Title: General relativity, collapse and singularities.
Authors: Wheeler, J. A.; Hughes, H. G.; Snyderman, N.; Lawrence,
J. K.; Zia, R. K. P.
Bibcode: 1974hear.conf..519W
Altcode:
No abstract at ADS
Title: Focusing of Gravitational Radiation into the Galactic Plane
Authors: Lawrence, J. K.
Bibcode: 1973PhRvD...7.2275L
Altcode:
We consider rays of gravitational radiation emitted near the event
horizon of a maximally rotating black hole at the galactic center,
aligned with the galactic rotation. If the emitting matter is
concentrated in the equatorial plane of the black hole, the focusing
effect of the metric will be concentrated in the galactic plane. An
average intensification of about an order of magnitude results at
the earth.
Title: Intensification of Gravitational Radiation by a Massive Rotator
Authors: Lawrence, John K.
Bibcode: 1972ApJ...171..483L
Altcode:
It is hypothesized that a massive, rotating, oblate object exists
at the center of our Galaxy, aligned with its plane. Under favorable
circumstances, gravitational waves emitted from the interior of the
object would be strongly focused by its gravitational field into the
galactic plane. An average intensification at the Earth of about an
order of magnitude would result.
Title: Gravitational Fermion interactions
Authors: Lawrence, John K.
Bibcode: 1971GReGr...2..215L
Altcode:
The scattering of unpolarized Fermions and scalar mesons by single
graviton exchange is considered by means of a Feynman graph type
perturbation theory scheme. In the limit of scattering of the Fermions
by very heavy mesons, one obtains the cross section for Fermions
scattering in a Schwarzschild metric. The result obtained conflicts
with an earlier result of Mitskevich. In the limit of scattering of
massless Fermions (neutrinos) with massless scalar mesons it is seen,
using Weinberg's treatment of soft graviton Bremsstrahlung, that the
cosmological red shift of light cannot be explained by interactions
of the light with intergalactic neutrinos.
Title: Focusing of Gravitational Radiation by the Galactic Core
Authors: Lawrence, J. K.
Bibcode: 1971PhRvD...3.3239L
Altcode:
The possibility is considered that the gravitational radiation observed
by Weber has an extragalactic origin and is focused by the galactic
core acting as a gravitational lens. While sufficient intensification
is possible, too few sources are correctly located for the effect to
be important.
Title: Focusing of gravitational radiation by interior gravitational
fields.
Authors: Lawrence, J. K.
Bibcode: 1971NCimB...6..225L
Altcode:
No abstract at ADS