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Author name code: gonzalez-manrique
ADS astronomy entries on 2022-09-14
author:"Gonzalez Manrique, Sergio Javier"
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Title: The European Solar Telescope
Authors: Quintero Noda, C.; Schlichenmaier, R.; Bellot Rubio, L. R.;
Löfdahl, M. G.; Khomenko, E.; Jurcak, J.; Leenaarts, J.; Kuckein,
C.; González Manrique, S. J.; Gunar, S.; Nelson, C. J.; de la Cruz
Rodríguez, J.; Tziotziou, K.; Tsiropoula, G.; Aulanier, G.; Collados,
M.; the EST team
2022arXiv220710905Q Altcode:
The European Solar Telescope (EST) is a project aimed at studying
the magnetic connectivity of the solar atmosphere, from the deep
photosphere to the upper chromosphere. Its design combines the knowledge
and expertise gathered by the European solar physics community during
the construction and operation of state-of-the-art solar telescopes
operating in visible and near-infrared wavelengths: the Swedish 1m Solar
Telescope (SST), the German Vacuum Tower Telescope (VTT) and GREGOR,
the French Télescope Héliographique pour l'Étude du Magnétisme
et des Instabilités Solaires (THÉMIS), and the Dutch Open Telescope
(DOT). With its 4.2 m primary mirror and an open configuration, EST will
become the most powerful European ground-based facility to study the Sun
in the coming decades in the visible and near-infrared bands. EST uses
the most innovative technological advances: the first adaptive secondary
mirror ever used in a solar telescope, a complex multi-conjugate
adaptive optics with deformable mirrors that form part of the optical
design in a natural way, a polarimetrically compensated telescope design
that eliminates the complex temporal variation and wavelength dependence
of the telescope Mueller matrix, and an instrument suite containing
several (etalon-based) tunable imaging spectropolarimeters and several
integral field unit spectropolarimeters. This publication summarises
some fundamental science questions that can be addressed with the
telescope, together with a complete description of its major subsystems.
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Title: Observational evidence for two-component distributions
describing solar magnetic bright points
Authors: Berrios Saavedra, Gerardine; Utz, Dominik; Vargas Domínguez,
Santiago; Campos Rozo, José Iván; González Manrique, Sergio Javier;
Gömöry, Peter; Kuckein, Christoph; Balthasar, Horst; Zelina, Peter
2022A&A...657A..79B Altcode: 2021arXiv211012404B
Context. High-resolution observations of the solar photosphere reveal
the presence of fine structures, in particular the so-called Magnetic
Bright Points (MBPs), which are small-scale features associated with
strong magnetic field regions of the order of kilogauss (kG). It
is especially relevant to study these magnetic elements, which are
extensively detected in all moments during the solar cycle, in order to
establish their contribution to the behavior of the solar atmosphere,
and ultimately a plausible role within the coronal heating problem. <BR
/> Aims: Characterisation of size and velocity distributions of MBPs in
the solar photosphere in two different datasets of quiet Sun images
acquired with high-resolution solar instruments i.e. Solar Optical
Telescope SOT/Hinode and the High-resolution Fast Imager HiFI/GREGOR,
in the G-band (4308 Å). <BR /> Methods: In order to detect the
MBPs, an automatic segmentation and identification algorithm is
used. Next, the identified features were tracked to measure their
proper motions. Finally, a statistical analysis of hundreds of MBPs is
carried out, generating histograms for areas, diameters and horizontal
velocities. <BR /> Results: This work establishes that areas and
diameters of MBPs display log-normal distributions that are well-fitted
by two different components, whereas the velocity vector components
follow Gaussians and the vector magnitude a Rayleigh distribution
revealing again for all vector elements a two component composition. <BR
/> Conclusions: The results can be interpreted as due to the presence of
two different populations of MBPs in the solar photosphere one likely
related to stronger network magnetic flux elements and the other one
to weaker intranetwork flux elemens. In particular this work concludes
on the effect of the different spatial resolution of GREGOR and Hinode
telescopes, affecting detections and average values.
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Title: Properties of the inner penumbra boundary and temporal
evolution of a decaying sunspot (Corrigendum)
Authors: Benko, M.; González Manrique, S. J.; Balthasar, H.; Gömöry,
P.; Kuckein, C.; Jurčák, J.
2021A&A...652C...7B Altcode:
No abstract at ADS
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Title: Evidence For Two-component Distributions Describing Magnetic
Bright Points In The Solar Photosphere
Authors: Vargas Domínguez, S.; Berrios Saavedra, G.; Utz, D.;
Campos Rozo, J. I.; González Manrique, S.; Gömöry, Peter; Kuckein,
Christoph; Balthasar, Horst; Zelina, Peter
2021AAS...23811310V Altcode:
High-resolution observations of the Sun reveal the presence of Magnetic
Bright Points (MBPs), which are small-scale features associated with
strong magnetic field regions, that are found all over the solar
photosphere. In this work, we characterize some physical properties
and dynamics of MBPs in a quiet Sun region by using time series of
images acquired with the High-resolution Fast Imager HiFI/GREGOR and
Solar Optical Telescope SOT/Hinode in the G-band (4308 Angstrom). An
automated segmentation algorithm is used to identify the MBPs and
track their evolution. The results show observational evidence for
two-component distributions of areas, diameters and velocities, that
can be interpreted as corresponding to different populations of MBPs.
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Title: Critical Science Plan for the Daniel K. Inouye Solar Telescope
(DKIST)
Authors: Rast, Mark P.; Bello González, Nazaret; Bellot Rubio,
Luis; Cao, Wenda; Cauzzi, Gianna; Deluca, Edward; de Pontieu, Bart;
Fletcher, Lyndsay; Gibson, Sarah E.; Judge, Philip G.; Katsukawa,
Yukio; Kazachenko, Maria D.; Khomenko, Elena; Landi, Enrico; Martínez
Pillet, Valentín; Petrie, Gordon J. D.; Qiu, Jiong; Rachmeler,
Laurel A.; Rempel, Matthias; Schmidt, Wolfgang; Scullion, Eamon; Sun,
Xudong; Welsch, Brian T.; Andretta, Vincenzo; Antolin, Patrick; Ayres,
Thomas R.; Balasubramaniam, K. S.; Ballai, Istvan; Berger, Thomas E.;
Bradshaw, Stephen J.; Campbell, Ryan J.; Carlsson, Mats; Casini,
Roberto; Centeno, Rebecca; Cranmer, Steven R.; Criscuoli, Serena;
Deforest, Craig; Deng, Yuanyong; Erdélyi, Robertus; Fedun, Viktor;
Fischer, Catherine E.; González Manrique, Sergio J.; Hahn, Michael;
Harra, Louise; Henriques, Vasco M. J.; Hurlburt, Neal E.; Jaeggli,
Sarah; Jafarzadeh, Shahin; Jain, Rekha; Jefferies, Stuart M.; Keys,
Peter H.; Kowalski, Adam F.; Kuckein, Christoph; Kuhn, Jeffrey R.;
Kuridze, David; Liu, Jiajia; Liu, Wei; Longcope, Dana; Mathioudakis,
Mihalis; McAteer, R. T. James; McIntosh, Scott W.; McKenzie, David
E.; Miralles, Mari Paz; Morton, Richard J.; Muglach, Karin; Nelson,
Chris J.; Panesar, Navdeep K.; Parenti, Susanna; Parnell, Clare E.;
Poduval, Bala; Reardon, Kevin P.; Reep, Jeffrey W.; Schad, Thomas A.;
Schmit, Donald; Sharma, Rahul; Socas-Navarro, Hector; Srivastava,
Abhishek K.; Sterling, Alphonse C.; Suematsu, Yoshinori; Tarr, Lucas
A.; Tiwari, Sanjiv; Tritschler, Alexandra; Verth, Gary; Vourlidas,
Angelos; Wang, Haimin; Wang, Yi-Ming; NSO and DKIST Project; DKIST
Instrument Scientists; DKIST Science Working Group; DKIST Critical
Science Plan Community
2021SoPh..296...70R Altcode: 2020arXiv200808203R
The National Science Foundation's Daniel K. Inouye Solar Telescope
(DKIST) will revolutionize our ability to measure, understand,
and model the basic physical processes that control the structure
and dynamics of the Sun and its atmosphere. The first-light DKIST
images, released publicly on 29 January 2020, only hint at the
extraordinary capabilities that will accompany full commissioning of
the five facility instruments. With this Critical Science Plan (CSP)
we attempt to anticipate some of what those capabilities will enable,
providing a snapshot of some of the scientific pursuits that the DKIST
hopes to engage as start-of-operations nears. The work builds on the
combined contributions of the DKIST Science Working Group (SWG) and
CSP Community members, who generously shared their experiences, plans,
knowledge, and dreams. Discussion is primarily focused on those issues
to which DKIST will uniquely contribute.
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Title: Chromospheric Resonances above Sunspots and Potential
Seismological Applications
Authors: Felipe, Tobias; Kuckein, Christoph; González Manrique,
Sergio Javier; Milic, Ivan; Sangeetha, C. R.
2020ApJ...900L..29F Altcode: 2020arXiv200810623F
Oscillations in sunspot umbrae exhibit remarkable differences
between the photosphere and chromosphere. We evaluate two competing
scenarios proposed for explaining those observations: a chromospheric
resonant cavity and waves traveling from the photosphere to upper
atmospheric layers. We have employed numerical simulations to
analyze the oscillations in both models. They have been compared with
observations in the low (Na I D<SUB>2</SUB>) and high (He I 10830 Å)
chromosphere. The nodes of the resonant cavity can be detected as
phase jumps or power dips, although the identification of the latter
is not sufficient to claim the existence of resonances. In contrast,
phase differences between velocity and temperature fluctuations reveal
standing waves and unequivocally prove the presence of an acoustic
resonator above umbrae. Our findings offer a new seismic method to probe
active region chromospheres through the detection of resonant nodes.
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Title: Determining the dynamics and magnetic fields in He I 10830
Å during a solar filament eruption
Authors: Kuckein, C.; González Manrique, S. J.; Kleint, L.; Asensio
Ramos, A.
2020A&A...640A..71K Altcode: 2020arXiv200610473K
<BR /> Aims: We investigate the dynamics and magnetic properties of
the plasma, including the line-of-sight velocity (LOS) and optical
depth, as well as the vertical and horizontal magnetic fields,
belonging to an erupted solar filament. <BR /> Methods: The filament
eruption was observed with the GREGOR Infrared Spectrograph at
the 1.5-meter GREGOR telescope on July 3, 2016. We acquired three
consecutive full-Stokes slit-spectropolarimetric scans in the He
I 10830 Å spectral range. The Stokes I profiles were classified
using the machine learning k-means algorithm and then inverted with
different initial conditions using the HAZEL code. <BR /> Results: The
erupting-filament material presents the following physical conditions:
(1) ubiquitous upward motions with peak LOS velocities of ∼73 km
s<SUP>-1</SUP>; (2) predominant large horizontal components of the
magnetic field, on average, in the range of 173-254 G, whereas the
vertical components of the fields are much lower, on average between
39 and 58 G; (3) optical depths in the range of 0.7-1.1. The average
azimuth orientation of the field lines between two consecutive
raster scans (<2.5 min) remained constant. <BR /> Conclusions:
The analyzed filament eruption belongs to the fast rising phase, with
total velocities of about 124 km s<SUP>-1</SUP>. The orientation of the
magnetic field lines does not change from one raster scan to the other,
indicating that the untwisting phase has not yet started. The untwisting
appears to start about 15 min after the beginning of the filament
eruption. <P />Movies attached to Figs. 1 and 3 are available at <A
href="https://www.aanda.org/10.1051/0004-6361/202038408/olm">https://www.aanda.org</A>
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Title: Solar observatory Einstein Tower: Data release of the digitized
solar full-disk photographic plate archive
Authors: Pal, Partha S.; Verma, Meetu; Rendtel, Jürgen; González
Manrique, Sergio Javier; Enke, Harry; Denker, Carsten
2020AN....341..575P Altcode: 2020arXiv200714744P
We present solar full-disk observations that were recorded
at the Einstein Tower during the years 1943-1991 (solar cycles
18-22). High-school students from Potsdam and Berlin digitized more than
3,500 full-disk images during 2-3-week internships at Leibniz-Institut
für Astrophysik Potsdam (AIP). The digital images cover a 15 cm × 15
cm region on photographic plates, which were scanned at a resolution
of 7,086 × 7,086 pixels. The raw data are monochromatic 8-bit images
in the tagged image file format (TIFF). These images were calibrated
and saved with improved photometric precision as 16-bit images with
2,048 × 2,048 pixels in the Flexible Image Transport System (FITS)
format, which contains extensive headers describing the full-disk
images and the observations. The various calibration steps include,
for example, accurate measurements of the solar radius, determination
of the limb-darkening function, and establishing an accurate coordinate
system. The contrast-enhanced and limb-darkening corrected images,
as well as the raw data, are freely available to researchers and
the general public in a publicly accessible repository. The data are
published as a special data release of the Archives of Photographic
PLates for Astronomical USE (APPLAUSE) project.
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Title: The dynamics of a solar arch filament system from the
chromosphere to the photosphere
Authors: González Manrique, S. J.; Kuckein, C.; Pastor Yabar, A.;
Diercke, A.; Collados, M.; Gömöry, P.; Zhong, S.; Hou, Y.; Denker, C.
2020sea..confE.199G Altcode:
We study the dynamics of plasma along the legs of an arch filament
system (AFS) from the chromosphere to the photosphere, observed with
high-cadence spectroscopic data from two ground-based solar telescopes:
the GREGOR telescope (Tenerife) using the GREGOR Infrared Spectrograph
in the He I 10830 Å range and the Swedish Solar Telescope (La Palma)
using the CRisp Imaging Spectro-Polarimeter to observe the Ca II 8542
Å and Fe I 6173 Å spectral lines. The temporal evolution of the
draining of the plasma was followed along the legs of a single arch
filament from the chromosphere to the photosphere. The average Doppler
velocities inferred at the upper chromosphere from the He I 10830 Å
triplet reach velocities up to 20-24 km s<SUP>-1</SUP>, and in the lower
chromosphere and upper photosphere the Doppler velocities reach up to
11 km s<SUP>-1</SUP> and 1.5 km s<SUP>-1</SUP> in the case of the Ca II
8542 Å and Si I 10827 Å spectral lines, respectively. The evolution
of the Doppler velocities at different layers of the solar atmosphere
(chromosphere and upper photosphere) shows that they follow the same
line-of-sight (LOS) velocity patern, which confirms the observational
evidence that the plasma drains toward the photosphere as proposed in
models of AFSs. The observations and the nonlinear force-free field
(NLFFF) extrapolations demonstrate that the magnetic field loops of
the AFS rise with time.
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Title: Chromospheric resonant cavities in umbrae: unequivocal
detection and seismic applications
Authors: Felipe, T.; Kuckein, C.; González Manrique, S. J.; Milic,
I.; Sangeetha, C. R.
2020sea..confE.196F Altcode:
Umbral chromospheric oscillations exhibit significant differences
compared to their photospheric counterparts. We evaluate two competing
scenarios proposed for explaining those observations: a chromospheric
resonant cavity and waves traveling from the photosphere to upper
atmospheric layers. The oscillatory signatures of both models have been
determined from numerical simulations, and they have been compared to
observations. We find that a high-frequency peak in the He I 10830 Å
power spectra cannot discriminate between both theories, contrary to the
claims of Jess et al. (2019). In contrast, phase differences between
velocity and temperature fluctuations reveal a standing pattern and
unequivocally prove the presence of an acoustic cavity above umbrae. Our
findings offer a new seismic method to probe sunspot chromospheres
through the identification of resonant nodes in phase spectra.
---------------------------------------------------------
Title: Determining the dynamics and magnetic fields in the
chromospheric He I 10830 Å triplet during a solar filament eruption
Authors: Kuckein, C.; González Manrique, S. J.; Kleint, L.; Asensio
Ramos, A.
2020sea..confE.202K Altcode:
We investigate the dynamics and magnetic properties of the plasma, such
as line-of-sight velocity (LOS), optical depth, vertical and horizontal
magnetic fields, belonging to an erupted solar filament. The filament
eruption was observed with the GREGOR Infrared Spectrograph (GRIS)
at the 1.5-meter GREGOR telescope on 2016 July 3. Three consecutive
full-Stokes slit-spectropolarimetric scans in the He I 10830 Å
spectral range were acquired. The Stokes I profiles were classified
using the machine learning k-means algorithm and then inverted with
different initial conditions using the inversion code HAZEL. The
erupting-filament material presents the following physical conditions:
(i) ubiquitous upward motions with peak LOS velocities of ∼73 km/s;
(ii) predominant large horizontal components of the magnetic field, on
average, in the range of 173-254 G, whereas the vertical components of
the fields are much lower, on average between 39-58 G; (iii) optical
depths in the range of 0.7-1.1. The average azimuth orientation of
the field lines between two consecutive raster scans (<2.5 minutes)
remained constant. The analyzed filament eruption belonged to the fast
rising phase, with total velocities of about 124 km/s.
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Title: Magnetic Flux Emergence in a Coronal Hole
Authors: Palacios, Judith; Utz, Dominik; Hofmeister, Stefan; Krikova,
Kilian; Gömöry, Peter; Kuckein, Christoph; Denker, Carsten; Verma,
Meetu; González Manrique, Sergio Javier; Campos Rozo, Jose Iván;
Koza, Július; Temmer, Manuela; Veronig, Astrid; Diercke, Andrea;
Kontogiannis, Ioannis; Cid, Consuelo
2020SoPh..295...64P Altcode: 2020arXiv200611779P
A joint campaign of various space-borne and ground-based observatories,
comprising the Japanese Hinode mission (Hinode Observing Plan 338,
20 - 30 September 2017), the GREGOR solar telescope, and the Vacuum
Tower Telescope (VTT), investigated numerous targets such as pores,
sunspots, and coronal holes. In this study, we focus on the coronal
hole region target. On 24 September 2017, a very extended non-polar
coronal hole developed patches of flux emergence, which contributed
to the decrease of the overall area of the coronal hole. These flux
emergence patches erode the coronal hole and transform the area into a
more quiet-Sun-like area, whereby bipolar magnetic structures play an
important role. Conversely, flux cancellation leads to the reduction
of opposite-polarity magnetic fields and to an increase in the area
of the coronal hole.
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Title: Tracking Downflows from the Chromosphere to the Photosphere
in a Solar Arch Filament System
Authors: González Manrique, Sergio Javier; Kuckein, Christoph;
Pastor Yabar, Adur; Diercke, Andrea; Collados, Manuel; Gömöry,
Peter; Zhong, Sihui; Hou, Yijun; Denker, Carsten
2020ApJ...890...82G Altcode: 2020arXiv200107078G
We study the dynamics of plasma along the legs of an arch filament
system (AFS) from the chromosphere to the photosphere, observed with
high-cadence spectroscopic data from two ground-based solar telescopes:
the GREGOR telescope (Tenerife) using the GREGOR Infrared Spectrograph
in the He I 10830 Å range and the Swedish Solar Telescope (La Palma)
using the CRisp Imaging Spectro-Polarimeter to observe the Ca II 8542
Å and Fe I 6173 Å spectral lines. The temporal evolution of the
draining of the plasma was followed along the legs of a single arch
filament from the chromosphere to the photosphere. The average Doppler
velocities inferred at the upper chromosphere from the He I 10830 Å
triplet reach velocities up to 20-24 km s<SUP>-1</SUP>, and in the lower
chromosphere and upper photosphere the Doppler velocities reach up to
11 km s<SUP>-1</SUP> and 1.5 km s<SUP>-1</SUP> in the case of the Ca II
8542 Å and Si I 10827 Å spectral lines, respectively. The evolution
of the Doppler velocities at different layers of the solar atmosphere
(chromosphere and upper photosphere) shows that they follow the same
line-of-sight (LOS) velocity pattern, which confirms the observational
evidence that the plasma drains toward the photosphere as proposed
in models of AFSs. The Doppler velocity maps inferred from the lower
photospheric Ca I 10839 Å or Fe I 6173 Å spectral lines do not
show the same LOS velocity pattern. Thus, there is no evidence that
the plasma reaches the lower photosphere. The observations and the
nonlinear force-free field (NLFFF) extrapolations demonstrate that
the magnetic field loops of the AFS rise with time. We found flow
asymmetries at different footpoints of the AFS. The NLFFF values of
the magnetic field strength help us to explain these flow asymmetries.
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Title: Capabilities of bisector analysis of the Si I 10 827 Å line
for estimating line-of-sight velocities in the quiet Sun
Authors: González Manrique, S. J.; Quintero Noda, C.; Kuckein, C.;
Ruiz Cobo, B.; Carlsson, M.
2020A&A...634A..19G Altcode: 2020arXiv200100508G
We examine the capabilities of a fast and simple method to infer
line-of-sight (LOS) velocities from observations of the photospheric
Si I 10 827 Å line. This spectral line is routinely observed together
with the chromospheric He I 10 830 Å triplet as it helps to constrain
the atmospheric parameters. We study the accuracy of bisector analysis
and a line core fit of Si I 10 827 Å. We employ synthetic profiles
starting from the Bifrost enhanced network simulation. The profiles are
computed solving the radiative transfer equation, including non-local
thermodynamic equilibrium effects on the determination of the atomic
level populations of Si I. We found a good correlation between the
inferred velocities from bisectors taken at different line profile
intensities and the original simulation velocity at given optical
depths. This good correlation means that we can associate bisectors
taken at different line-profile percentages with atmospheric layers
that linearly increase as we scan lower spectral line intensities. We
also determined that a fit to the line-core intensity is robust and
reliable, providing information about atmospheric layers that are
above those accessible through bisectors. Therefore, by combining
both methods on the Si I 10 827 Å line, we can seamlessly trace the
quiet-Sun LOS velocity stratification from the deep photosphere to
higher layers until around logτ = -3.5 in a fast and straightforward
way. This method is ideal for generating quick-look reference images
for future missions like the Daniel K. Inoue Solar Telescope and the
European Solar Telescope, for example.
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Title: The magnetic structure and dynamics of a decaying active region
Authors: Kontogiannis, Ioannis; Kuckein, Christoph; González
Manrique, Sergio Javier; Felipe, Tobias; Verma, Meetu; Balthasar,
Horst; Denker, Carsten
2020IAUS..354...53K Altcode:
We study the evolution of the decaying active region NOAA 12708, from
the photosphere up to the corona using high resolution, multi-wavelength
GREGOR observations taken on May 9, 2018. We utilize spectropolarimetric
scans of the 10830 Å spectral range by the GREGOR Infrared Spectrograph
(GRIS), spectral imaging time-series in the Na ID<SUP>2</SUP> spectral
line by the GREGOR Fabry-Pérot Interferometer (GFPI) and context
imaging in the Ca IIH and blue continuum by the High-resolution Fast
Imager (HiFI). Context imaging in the UV/EUV from the Atmospheric
Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO)
complements our dataset. The region under study contains one pore with a
light-bridge, a few micro-pores and extended clusters of magnetic bright
points. We study the magnetic structure from the photosphere up to the
upper chromosphere through the spectropolarimetric observations in He
II and Si I and through the magnetograms provided by the Helioseismic
and Magnetic Imager (HMI). The high-resolution photospheric images
reveal the complex interaction between granular-scale convective
motions and a range of scales of magnetic field concentrations in
unprecedented detail. The pore itself shows a strong interaction with
the convective motions, which eventually leads to its decay, while,
under the influence of the photospheric flow field, micro-pores
appear and disappear. Compressible waves are generated, which are
guided towards the upper atmosphere along the magnetic field lines of
the various magnetic structures within the field-of-view. Modelling
of the He i absorption profiles reveals high velocity components,
mostly associated with magnetic bright points at the periphery
of the active region, many of which correspond to asymmetric Si I
Stokes-V profiles revealing a coupling between upper photospheric
and upper chromospheric dynamics. Time-series of Na ID<SUP>2</SUP>
spectral images reveal episodic high velocity components at the same
locations. State-of-the-art multi-wavelength GREGOR observations allow
us to track and understand the mechanisms at work during the decay
phase of the active region.
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Title: Coordinated observations between China and Europe to follow
active region 12709
Authors: González Manrique, S. J.; Kuckein, C.; Gömöry, P.; Yuan,
S.; Xu, Z.; Rybák, J.; Balthasar, H.; Schwartz, P.
2020IAUS..354...58G Altcode: 2020IAUS..354...58M; 2019arXiv191208611G
We present the first images of a coordinated campaign to follow active
region NOAA 12709 on 2018 May 13 as part of a joint effort between
three observatories (China-Europe). The active region was close to
disk center and enclosed a small pore, a tight polarity inversion line
and a filament in the chromosphere. The active region was observed
with the 1.5-meter GREGOR solar telescope on Tenerife (Spain) with
spectropolarimetry using GRIS in the He i 10830 Å spectral range
and with HiFI using two broad-band filter channels. In addition,
the Lomnicky Stit Observatory (LSO, Slovakia) recorded the same
active region with the new Solar Chromospheric Detector (SCD) in
spectroscopic mode at Hα 6562 Å. The third ground-based telescope
was located at the Fuxian Solar Observatory (China), where the active
region was observed with the 1-meter New Vacuum Solar Telescope
(NVST), using the Multi-Channel High Resolution Imaging System at
Hα 6562 Å. Overlapping images of the active region from all three
telescopes will be shown as well as preliminary Doppler line-of-sight
(LOS) velocities. The potential of such observations are discussed.
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Title: Cloud model inversions of strong chromospheric absorption
lines using principal component analysis
Authors: Dineva, Ekaterina; Verma, Meetu; González Manrique, Sergio
J.; Schwartz, Pavol; Denker, Carsten
2020AN....341...64D Altcode: 2019arXiv191210476D
High-resolution spectroscopy of strong chromospheric absorption
lines delivers nowadays several millions of spectra per observing
day, when using fast scanning devices to cover large regions on
the solar surface. Therefore, fast and robust inversion schemes are
needed to explore the large data volume. Cloud model (CM) inversions
of the chromospheric Hα line are commonly employed to investigate
various solar features including filaments, prominences, surges, jets,
mottles, and (macro-) spicules. The choice of the CM was governed by
its intuitive description of complex chromospheric structures as clouds
suspended above the solar surface by magnetic fields. This study is
based on observations of active region NOAA 11126 in Hα, which were
obtained November 18-23, 2010 with the echelle spectrograph of the
vacuum tower telescope at the Observatorio del Teide, Spain. Principal
component analysis reduces the dimensionality of spectra and conditions
noise-stripped spectra for CM inversions. Modeled Hα intensity and
contrast profiles as well as CM parameters are collected in a database,
which facilitates efficient processing of the observed spectra. Physical
maps are computed representing the line-core and continuum intensity,
absolute contrast, equivalent width, and Doppler velocities, among
others. Noise-free spectra expedite the analysis of bisectors. The data
processing is evaluated in the context of "big data," in particular
with respect to automatic classification of spectra.
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Title: Revisiting the building blocks of solar magnetic fields
by GREGOR
Authors: Utz, Dominik; Kuckein, Christoph; Campos Rozo, Jose Iván;
González Manrique, Sergio Javier; Balthasar, Horst; Gömöry,
Peter; Hernández, Judith Palacios; Denker, Carsten; Verma, Meetu;
Kontogiannis, Ioannis; Krikova, Kilian; Hofmeister, Stefan; Diercke,
Andrea
2020IAUS..354...38U Altcode:
The Sun is our dynamic host star due to its magnetic fields causing
plentiful of activity in its atmosphere. From high energetic flares
and coronal mass ejections (CMEs) to lower energetic phenomena such
as jets and fibrils. Thus, it is of crucial importance to learn about
formation and evolution of solar magnetic fields. These fields cover a
wide range of spatial and temporal scales, starting on the larger end
with active regions harbouring complex sunspots, via isolated pores,
down to the smallest yet resolved elements - so-called magnetic bright
points (MBPs). Here, we revisit the various manifestations of solar
magnetic fields by the largest European solar telescope in operation,
the 1.5-meter GREGOR telescope. We show images from the High-resolution
Fast Imager (HiFI) and spectropolarimetric data from the GREGOR Infrared
Spectrograph (GRIS). Besides, we outline resolved convective features
inside the larger structures - so-called light-bridges occurring on
large to mid-sized scales.
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Title: Polarimetry with the GREGOR Fabry-Pérot Interferometer
Authors: Balthasar, H.; Gisler, D.; González Manrique, S. J.; Kuckein,
C.; Verma, M.; Denker, C.
2019spw..confE...3B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Spectropolarimetric Observations of an Arch Filament System
with GREGOR
Authors: Balthasar, H.; Gömöry, P.; González Manrique, S. J.;
Kuckein, C.; Kučera, A.; Schwartz, P.; Berkefeld, T.; Collados, M.;
Denker, C.; Feller, A.; Hofmann, A.; Schlichenmaier, R.; Schmidt,
D.; Schmidt, W.; Sigwarth, M.; Sobotka, M.; Solanki, S. K.; Soltau,
D.; Staude, J.; Strassmeier, K. G.; von der Lühe, O.
2019ASPC..526..217B Altcode: 2018arXiv180401789B
We observed an arch filament system (AFS) in a sunspot group with the
GREGOR Infrared Spectrograph attached to the GREGOR solar telescope. The
AFS was located between the leading sunspot of negative polarity and
several pores of positive polarity forming the following part of the
sunspot group. We recorded five spectro-polarimetric scans of this
region. The spectral range included the spectral lines Si I 1082.7
nm, He I 1083.0 nm, and Ca I 1083.9 nm. In this work we concentrate
on the silicon line which is formed in the upper photosphere. The
line profiles are inverted with the code 'Stokes Inversion based
on Response functions' to obtain the magnetic field vector. The
line-of-sight velocities are determined independently with a Fourier
phase method. Maximum velocities are found close to the ends of AFS
fibrils. These maximum values amount to 2.4 km s<SUP>-1</SUP> next
to the pores and to 4 km s<SUP>-1</SUP> at the sunspot side. Between
the following pores, we encounter an area of negative polarity that
is decreasing during the five scans. We interpret this by new emerging
positive flux in this area canceling out the negative flux. In summary,
our findings confirm the scenario that rising magnetic flux tubes
cause the AFS.
---------------------------------------------------------
Title: Photospheric Magnetic Fields of the Trailing Sunspots in
Active Region NOAA 12396
Authors: Verma, M.; Balthasar, H.; Denker, C.; Böhm, F.; Fischer,
C. E.; Kuckein, C.; González Manrique, S. J.; Sobotka, M.; Bello
González, N.; Diercke, A.; Berkefeld, T.; Collados, M.; Feller, A.;
Hofmann, A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pastor Yabar,
A.; Rezaei, R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth,
M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K.; Volkmer,
R.; von der Lühe, O.; Waldmann, T.
2019ASPC..526..291V Altcode: 2018arXiv180507752V
The solar magnetic field is responsible for all aspects of solar
activity. Sunspots are the main manifestation of the ensuing solar
activity. Combining high-resolution and synoptic observations has
the ambition to provide a comprehensive description of the sunspot
growth and decay processes. Active region NOAA 12396 emerged on 2015
August 3 and was observed three days later with the 1.5-meter GREGOR
solar telescope on 2015 August 6. High-resolution spectropolarimetric
data from the GREGOR Infrared Spectrograph (GRIS) are obtained in the
photospheric lines Si I λ1082.7 nm and Ca I λ1083.9 nm, together
with the chromospheric He I λ1083.0 nm triplet. These near-infrared
spectropolarimetric observations were complemented by synoptic
line-of-sight magnetograms and continuum images of the Helioseismic
and Magnetic Imager (HMI) and EUV images of the Atmospheric Imaging
Assembly (AIA) on board the Solar Dynamics Observatory (SDO).
---------------------------------------------------------
Title: Properties of the inner penumbral boundary and temporal
evolution of a decaying sunspot
Authors: Benko, M.; González Manrique, S. J.; Balthasar, H.; Gömöry,
P.; Kuckein, C.; Jurčák, J.
2018A&A...620A.191B Altcode: 2018arXiv181013185B
Context. It has been empirically determined that the umbra-penumbra
boundaries of stable sunspots are characterized by a constant value of
the vertical magnetic field. <BR /> Aims: We analyzed the evolution
of the photospheric magnetic field properties of a decaying sunspot
belonging to NOAA 11277 between August 28-September 3, 2011. The
observations were acquired with the spectropolarimeter on-board of
the Hinode satellite. We aim to prove the validity of the constant
vertical magnetic-field boundary between the umbra and penumbra in
decaying sunspots. <BR /> Methods: A spectral-line inversion technique
was used to infer the magnetic field vector from the full-Stokes
profiles. In total, eight maps were inverted and the variation of
the magnetic properties in time were quantified using linear or
quadratic fits. <BR /> Results: We find a linear decay of the umbral
vertical magnetic field, magnetic flux, and area. The penumbra showed
a linear increase of the vertical magnetic field and a sharp decay
of the magnetic flux. In addition, the penumbral area quadratically
decayed. The vertical component of the magnetic field is weaker on the
umbra-penumbra boundary of the studied decaying sunspot compared to
stable sunspots. Its value seem to be steadily decreasing during the
decay phase. Moreover, at any time of the sunspot decay shown, the inner
penumbra boundary does not match with a constant value of the vertical
magnetic field, contrary to what is seen in stable sunspots. <BR />
Conclusions: During the decaying phase of the studied sunspot, the
umbra does not have a sufficiently strong vertical component of the
magnetic field and is thus unstable and prone to be disintegrated by
convection or magnetic diffusion. No constant value of the vertical
magnetic field is found for the inner penumbral boundary.
---------------------------------------------------------
Title: sTools - a software package for data reduction of GREGOR
instruments and general data analysis
Authors: Kuckein, Christoph; Denker, Carsten; Verma, Meetu; Balthasar,
Horst; Diercke, Andrea; González Manrique, Sergio Javier; Dineva,
Ekaterina; Kontogiannis, Ioannis; Shen, Zili
2018csc..confE.105K Altcode:
The optical solar physics group at AIP is responsible for the GREGOR
Fabry-Perot Interferometer (GFPI) and the large-format facility cameras
(Blue Imaging Channel (BIC) and High-resolution Fast Imager (HiFI))
at the 1.5-meter GREGOR solar telescope (Tenerife, Spain). Since
the »Early Science Phase« of the telescope in 2014, the group
developed a data reduction pipeline for these two instruments. The
pipeline »sTools« is based on the Interactive Data Language
(IDL) and delivers reduced and image-restored data with a minimum
of user interaction. Furthermore, it creates quick-look data and
builds a webpage with an overview of the observations and their
statistics (http://gregor.aip.de). However, during the last years,
sTools continuously evolved and currently hosts many additional
routines for data analysis: (1) A local correlation tracking (LCT)
algorithm adapted for both high-resolution (GREGOR and Hinode) and
synoptic full-disk (SDO) data. (2) A new quantitative tool, i.e.,
a Background-subtracted Solar Activity Map (BaSAM), to assess and
visualize the temporal variation of the photospheric magnetic field
and the EUV 160 nm intensity. This method utilizes SDO data and is
applicable to both full-disk observations and regions-of-interest. (3)
Calibration of synoptic full-disk data from the Chromospheric Telescope
(ChroTel) including extraction of Doppler velocities from He I 1083
nm filtergrams. (4) Analysis tools for sun-as-a-star spectroscopy
for the Solar Disk-Integrated (SDI) telescope of the Potsdam Echelle
Polarimetric and Spectroscopic Instrument (PEPSI). sTools is licensed
under a creative commons license and is freely available, after
registration, at the abovementioned website.
---------------------------------------------------------
Title: Temporal evolution of arch filaments as seen in He I 10 830 Å
Authors: González Manrique, S. J.; Kuckein, C.; Collados, M.; Denker,
C.; Solanki, S. K.; Gömöry, P.; Verma, M.; Balthasar, H.; Lagg,
A.; Diercke, A.
2018A&A...617A..55G Altcode: 2018arXiv180700728G
<BR /> Aims: We study the evolution of an arch filament system (AFS)
and of its individual arch filaments to learn about the processes
occurring in them. <BR /> Methods: We observed the AFS at the
GREGOR solar telescope on Tenerife at high cadence with the very
fast spectroscopic mode of the GREGOR Infrared Spectrograph (GRIS)
in the He I 10 830 Å spectral range. The He I triplet profiles
were fitted with analytic functions to infer line-of-sight (LOS)
velocities to follow plasma motions within the AFS. <BR /> Results:
We tracked the temporal evolution of an individual arch filament
over its entire lifetime, as seen in the He I 10 830 Å triplet. The
arch filament expanded in height and extended in length from 13″ to
21″. The lifetime of this arch filament is about 30 min. About 11
min after the arch filament is seen in He I, the loop top starts to
rise with an average Doppler velocity of 6 km s<SUP>-1</SUP>. Only two
minutes later, plasma drains down with supersonic velocities towards
the footpoints reaching a peak velocity of up to 40 km s<SUP>-1</SUP>
in the chromosphere. The temporal evolution of He I 10 830 Å profiles
near the leading pore showed almost ubiquitous dual red components of
the He I triplet, indicating strong downflows, along with material
nearly at rest within the same resolution element during the whole
observing time. <BR /> Conclusions: We followed the arch filament as it
carried plasma during its rise from the photosphere to the corona. The
material then drained toward the photosphere, reaching supersonic
velocities, along the legs of the arch filament. Our observational
results support theoretical AFS models and aids in improving future
models. <P />The movie associated to Fig. 3 is available at <A
href="https://www.aanda.org/10.1051/0004-6361/201832684/olm">https://www.aanda.org/</A>
---------------------------------------------------------
Title: High-resolution imaging and near-infrared spectroscopy of
penumbral decay
Authors: Verma, M.; Denker, C.; Balthasar, H.; Kuckein, C.; Rezaei,
R.; Sobotka, M.; Deng, N.; Wang, H.; Tritschler, A.; Collados, M.;
Diercke, A.; González Manrique, S. J.
2018A&A...614A...2V Altcode: 2018arXiv180103686V
<BR /> Aims: Combining high-resolution spectropolarimetric and imaging
data is key to understanding the decay process of sunspots as it
allows us to scrutinize the velocity and magnetic fields of sunspots
and their surroundings. <BR /> Methods: Active region NOAA 12597
was observed on 2016 September 24 with the 1.5-meter GREGOR solar
telescope using high-spatial-resolution imaging as well as imaging
spectroscopy and near-infrared (NIR) spectropolarimetry. Horizontal
proper motions were estimated with local correlation tracking, whereas
line-of-sight (LOS) velocities were computed with spectral line fitting
methods. The magnetic field properties were inferred with the "Stokes
Inversions based on Response functions" (SIR) code for the Si I and Ca
I NIR lines. <BR /> Results: At the time of the GREGOR observations,
the leading sunspot had two light bridges indicating the onset of
its decay. One of the light bridges disappeared, and an elongated,
dark umbral core at its edge appeared in a decaying penumbral sector
facing the newly emerging flux. The flow and magnetic field properties
of this penumbral sector exhibited weak Evershed flow, moat flow, and
horizontal magnetic field. The penumbral gap adjacent to the elongated
umbral core and the penumbra in that penumbral sector displayed LOS
velocities similar to granulation. The separating polarities of a new
flux system interacted with the leading and central part of the already
established active region. As a consequence, the leading spot rotated
55° clockwise over 12 h. <BR /> Conclusions: In the high-resolution
observations of a decaying sunspot, the penumbral filaments facing the
flux emergence site contained a darkened area resembling an umbral core
filled with umbral dots. This umbral core had velocity and magnetic
field properties similar to the sunspot umbra. This implies that the
horizontal magnetic fields in the decaying penumbra became vertical
as observed in flare-induced rapid penumbral decay, but on a very
different time-scale.
---------------------------------------------------------
Title: High-cadence Imaging and Imaging Spectroscopy at the
GREGOR Solar Telescope—A Collaborative Research Environment for
High-resolution Solar Physics
Authors: Denker, Carsten; Kuckein, Christoph; Verma, Meetu; González
Manrique, Sergio J.; Diercke, Andrea; Enke, Harry; Klar, Jochen;
Balthasar, Horst; Louis, Rohan E.; Dineva, Ekaterina
2018ApJS..236....5D Altcode: 2018arXiv180210146D
In high-resolution solar physics, the volume and complexity
of photometric, spectroscopic, and polarimetric ground-based
data significantly increased in the last decade, reaching data
acquisition rates of terabytes per hour. This is driven by the
desire to capture fast processes on the Sun and the necessity
for short exposure times “freezing” the atmospheric seeing,
thus enabling ex post facto image restoration. Consequently,
large-format and high-cadence detectors are nowadays used in
solar observations to facilitate image restoration. Based on our
experience during the “early science” phase with the 1.5 m
GREGOR solar telescope (2014-2015) and the subsequent transition
to routine observations in 2016, we describe data collection and
data management tailored toward image restoration and imaging
spectroscopy. We outline our approaches regarding data processing,
analysis, and archiving for two of GREGOR’s post-focus instruments
(see <A href="http://gregor.aip.de">http://gregor.aip.de</A>), i.e.,
the GREGOR Fabry-Pérot Interferometer (GFPI) and the newly installed
High-Resolution Fast Imager (HiFI). The heterogeneous and complex
nature of multidimensional data arising from high-resolution solar
observations provides an intriguing but also a challenging example for
“big data” in astronomy. The big data challenge has two aspects: (1)
establishing a workflow for publishing the data for the whole community
and beyond and (2) creating a collaborative research environment
(CRE), where computationally intense data and postprocessing tools are
colocated and collaborative work is enabled for scientists of multiple
institutes. This requires either collaboration with a data center or
frameworks and databases capable of dealing with huge data sets based on
virtual observatory (VO) and other community standards and procedures.
---------------------------------------------------------
Title: Image Quality in High-resolution and High-cadence Solar Imaging
Authors: Denker, C.; Dineva, E.; Balthasar, H.; Verma, M.; Kuckein,
C.; Diercke, A.; González Manrique, S. J.
2018SoPh..293...44D Altcode: 2018arXiv180200760D
Broad-band imaging and even imaging with a moderate bandpass (about 1
nm) provides a photon-rich environment, where frame selection (lucky
imaging) becomes a helpful tool in image restoration, allowing us to
perform a cost-benefit analysis on how to design observing sequences
for imaging with high spatial resolution in combination with real-time
correction provided by an adaptive optics (AO) system. This study
presents high-cadence (160 Hz) G-band and blue continuum image sequences
obtained with the High-resolution Fast Imager (HiFI) at the 1.5-meter
GREGOR solar telescope, where the speckle-masking technique is used
to restore images with nearly diffraction-limited resolution. The
HiFI employs two synchronized large-format and high-cadence sCMOS
detectors. The median filter gradient similarity (MFGS) image-quality
metric is applied, among others, to AO-corrected image sequences of
a pore and a small sunspot observed on 2017 June 4 and 5. A small
region of interest, which was selected for fast-imaging performance,
covered these contrast-rich features and their neighborhood, which were
part of Active Region NOAA 12661. Modifications of the MFGS algorithm
uncover the field- and structure-dependency of this image-quality
metric. However, MFGS still remains a good choice for determining image
quality without a priori knowledge, which is an important characteristic
when classifying the huge number of high-resolution images contained in
data archives. In addition, this investigation demonstrates that a fast
cadence and millisecond exposure times are still insufficient to reach
the coherence time of daytime seeing. Nonetheless, the analysis shows
that data acquisition rates exceeding 50 Hz are required to capture a
substantial fraction of the best seeing moments, significantly boosting
the performance of post-facto image restoration.
---------------------------------------------------------
Title: Ca II 8542 Å brightenings induced by a solar microflare
Authors: Kuckein, C.; Diercke, A.; González Manrique, S. J.; Verma,
M.; Löhner-Böttcher, J.; Socas-Navarro, H.; Balthasar, H.; Sobotka,
M.; Denker, C.
2017A&A...608A.117K Altcode: 2017arXiv170906861K
<BR /> Aims: We study small-scale brightenings in Ca II 8542 Å
line-core images to determine their nature and effect on localized
heating and mass transfer in active regions. <BR /> Methods:
High-resolution two-dimensional spectroscopic observations of a solar
active region in the near-infrared Ca II 8542 Å line were acquired
with the GREGOR Fabry-Pérot Interferometer attached to the 1.5-m GREGOR
telescope. Inversions of the spectra were carried out using the NICOLE
code to infer temperatures and line-of-sight (LOS) velocities. Response
functions of the Ca II line were computed for temperature and LOS
velocity variations. Filtergrams of the Atmospheric Imaging Assembly
(AIA) and magnetograms of the Helioseismic and Magnetic Imager (HMI)
were coaligned to match the ground-based observations and to follow the
Ca II brightenings along all available layers of the atmosphere. <BR />
Results: We identified three brightenings of sizes up to 2” × 2”
that appeared in the Ca II 8542 Å line-core images. Their lifetimes
were at least 1.5 min. We found evidence that the brightenings belonged
to the footpoints of a microflare (MF). The properties of the observed
brightenings disqualified the scenarios of Ellerman bombs or Interface
Region Imaging Spectrograph (IRIS) bombs. However, this MF shared some
common properties with flaring active-region fibrils or flaring arch
filaments (FAFs): (1) FAFs and MFs are both apparent in chromospheric
and coronal layers according to the AIA channels; and (2) both show
flaring arches with lifetimes of about 3.0-3.5 min and lengths of
20” next to the brightenings. The inversions revealed heating by
600 K at the footpoint location in the ambient chromosphere during
the impulsive phase. Connecting the footpoints, a dark filamentary
structure appeared in the Ca II line-core images. Before the
start of the MF, the spectra of this structure already indicated
average blueshifts, meaning upward motions of the plasma along the
LOS. During the impulsive phase, these velocities increased up to -
2.2 km s<SUP>-1</SUP>. The structure did not disappear during the
observations. Downflows dominated at the footpoints. However, in
the upper photosphere, slight upflows occurred during the impulsive
phase. Hence, bidirectional flows are present in the footpoints
of the MF. <BR /> Conclusions: We detected Ca II brightenings that
coincided with the footpoint location of an MF. The MF event led to
a rise of plasma in the upper photosphere, both before and during the
impulsive phase. Excess mass, previously raised to at most chromospheric
layers, slowly drained downward along arches toward the footpoints
of the MF. <P />The movie associated to Fig. 2 is available at <A
href="http://www.aanda.org/10.1051/0004-6361/201731319/olm">http://www.aanda.org</A>
---------------------------------------------------------
Title: sTools - a data reduction pipeline for the GREGOR Fabry-Pérot
Interferometer and the High-resolution Fast Imager at the GREGOR
solar telescope
Authors: Kuckein, C.; Denker, C.; Verma, M.; Balthasar, H.; González
Manrique, S. J.; Louis, R. E.; Diercke, A.
2017IAUS..327...20K Altcode: 2017arXiv170101670K
A huge amount of data has been acquired with the GREGOR Fabry-Pérot
Interferometer (GFPI), large-format facility cameras, and since 2016
with the High-resolution Fast Imager (HiFI). These data are processed
in standardized procedures with the aim of providing science-ready data
for the solar physics community. For this purpose, we have developed a
user-friendly data reduction pipeline called “sTools” based on the
Interactive Data Language (IDL) and licensed under creative commons
license. The pipeline delivers reduced and image-reconstructed data
with a minimum of user interaction. Furthermore, quick-look data are
generated as well as a webpage with an overview of the observations and
their statistics. All the processed data are stored online at the GREGOR
GFPI and HiFI data archive of the Leibniz Institute for Astrophysics
Potsdam (AIP). The principles of the pipeline are presented together
with selected high-resolution spectral scans and images processed
with sTools.
---------------------------------------------------------
Title: Flows along arch filaments observed in the GRIS `very fast
spectroscopic mode'
Authors: González Manrique, S. J.; Denker, C.; Kuckein, C.; Pastor
Yabar, A.; Collados, M.; Verma, M.; Balthasar, H.; Diercke, A.;
Fischer, C. E.; Gömöry, P.; Bello González, N.; Schlichenmaier,
R.; Cubas Armas, M.; Berkefeld, T.; Feller, A.; Hoch, S.; Hofmann,
A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Schmidt, D.; Schmidt,
W.; Sigwarth, M.; Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude,
J.; Strassmeier, K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
2017IAUS..327...28G Altcode: 2017arXiv170102206G
A new generation of solar instruments provides improved spectral,
spatial, and temporal resolution, thus facilitating a better
understanding of dynamic processes on the Sun. High-resolution
observations often reveal multiple-component spectral line profiles,
e.g., in the near-infrared He i 10830 Å triplet, which provides
information about the chromospheric velocity and magnetic fine
structure. We observed an emerging flux region, including two small
pores and an arch filament system, on 2015 April 17 with the `very
fast spectroscopic mode' of the GREGOR Infrared Spectrograph (GRIS)
situated at the 1.5-meter GREGOR solar telescope at Observatorio del
Teide, Tenerife, Spain. We discuss this method of obtaining fast (one
per minute) spectral scans of the solar surface and its potential to
follow dynamic processes on the Sun. We demonstrate the performance
of the `very fast spectroscopic mode' by tracking chromospheric
high-velocity features in the arch filament system.
---------------------------------------------------------
Title: Flare-induced changes of the photospheric magnetic field in
a δ-spot deduced from ground-based observations
Authors: Gömöry, P.; Balthasar, H.; Kuckein, C.; Koza, J.;
Veronig, A. M.; González Manrique, S. J.; Kučera, A.; Schwartz,
P.; Hanslmeier, A.
2017A&A...602A..60G Altcode: 2017arXiv170406089G
<BR /> Aims: Changes of the magnetic field and the line-of-sight
velocities in the photosphere are being reported for an M-class
flare that originated at a δ-spot belonging to active region NOAA
11865. <BR /> Methods: High-resolution ground-based near-infrared
spectropolarimetric observations were acquired simultaneously in
two photospheric spectral lines, Fe I 10783 Å and Si I 10786 Å,
with the Tenerife Infrared Polarimeter at the Vacuum Tower Telescope
(VTT) in Tenerife on 2013 October 15. The observations covered several
stages of the M-class flare. Inversions of the full-Stokes vector of
both lines were carried out and the results were put into context using
(extreme)-ultraviolet filtergrams from the Solar Dynamics Observatory
(SDO). <BR /> Results: The active region showed high flaring activity
during the whole observing period. After the M-class flare, the
longitudinal magnetic field did not show significant changes along
the polarity inversion line (PIL). However, an enhancement of the
transverse magnetic field of approximately 550 G was found that
bridges the PIL and connects umbrae of opposite polarities in the
δ-spot. At the same time, a newly formed system of loops appeared
co-spatially in the corona as seen in 171 Å filtergrams of the
Atmospheric Imaging Assembly (AIA) on board SDO. However, we cannot
exclude that the magnetic connection between the umbrae already existed
in the upper atmosphere before the M-class flare and became visible
only later when it was filled with hot plasma. The photospheric
Doppler velocities show a persistent upflow pattern along the PIL
without significant changes due to the flare. <BR /> Conclusions:
The increase of the transverse component of the magnetic field after
the flare together with the newly formed loop system in the corona
support recent predictions of flare models and flare observations. <P
/>The movie associated to Figs. 4 and 5 is available at <A
href="http://www.aanda.org/10.1051/0004-6361/201730644/olm">http://www.aanda.org</A>
---------------------------------------------------------
Title: High-resolution imaging spectroscopy of two micro-pores and
an arch filament system in a small emerging-flux region
Authors: González Manrique, S. J.; Bello González, N.; Denker, C.
2017A&A...600A..38G Altcode: 2017arXiv170310140G
Context. Emerging flux regions mark the first stage in the accumulation
of magnetic flux eventually leading to pores, sunspots, and (complex)
active regions. These flux regions are highly dynamic, show a variety
of fine structure, and in many cases live only for a short time (less
than a day) before dissolving quickly into the ubiquitous quiet-Sun
magnetic field. <BR /> Aims: The purpose of this investigation is to
characterize the temporal evolution of a minute emerging flux region,
the associated photospheric and chromospheric flow fields, and the
properties of the accompanying arch filament system. We aim to explore
flux emergence and decay processes and investigate if they scale with
structure size and magnetic flux contents. <BR /> Methods: This study
is based on imaging spectroscopy with the Göttingen Fabry-Pérot
Interferometer at the Vacuum Tower Telescope, Observatorio del Teide,
Tenerife, Spain on 2008 August 7. Photospheric horizontal proper motions
were measured with Local correlation tracking using broadband images
restored with multi-object multi-frame blind deconvolution. Cloud model
(CM) inversions of line scans in the strong chromospheric absorption
Hαλ656.28 nm line yielded CM parameters (Doppler velocity, Doppler
width, optical thickness, and source function), which describe the
cool plasma contained in the arch filament system. <BR /> Results:
The high-resolution observations cover the decay and convergence of two
micro-pores with diameters of less than one arcsecond and provide decay
rates for intensity and area. The photospheric horizontal flow speed
is suppressed near the two micro-pores indicating that the magnetic
field is already sufficiently strong to affect the convective energy
transport. The micro-pores are accompanied by a small arch filament
system as seen in Hα, where small-scale loops connect two regions
with Hα line-core brightenings containing an emerging flux region
with opposite polarities. The Doppler width, optical thickness,
and source function reach the largest values near the Hα line-core
brightenings. The chromospheric velocity of the cloud material is
predominantly directed downwards near the footpoints of the loops
with velocities of up to 12 km s<SUP>-1</SUP>, whereas loop tops show
upward motions of about 3 km s<SUP>-1</SUP>. Some of the loops exhibit
signs of twisting motions along the loop axis. <BR /> Conclusions:
Micro-pores are the smallest magnetic field concentrations leaving a
photometric signature in the photosphere. In the observed case, they
are accompanied by a miniature arch filament system indicative of newly
emerging flux in the form of Ω-loops. Flux emergence and decay take
place on a time-scale of about two days, whereas the photometric decay
of the micro-pores is much more rapid (a few hours), which is consistent
with the incipient submergence of Ω-loops. Considering lifetime and
evolution timescales, impact on the surrounding photospheric proper
motions, and flow speed of the chromospheric plasma at the loop tops
and footpoints, the results are representative for the smallest emerging
flux regions still recognizable as such.
---------------------------------------------------------
Title: Photospheric and chromospheric observations of dynamic features
in an arch filament system
Authors: González Manrique, S. J.
2017psio.confE..38G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Center-to-limb variation of the velocity field in and around
a sunspot with light-bridges
Authors: Denker, Carsten; Verma, Meetu; Balthasar, Horst; Diercke,
Andrea; González Manrique, S. J.; Löhner-Böttcher, Johannes;
Kuckein, Christoph; Sobotka, Michal
2017psio.confE.104D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Velocity fields in sunspots derived from observations with
the GREGOR Fabry-Pérot Interferometer
Authors: Balthasar, H.; Denker, C.; Diercke, A.; González Manrique,
S. J.; Kuckein, C.; Louis, R. E.; Verma, M., Löhner-Böttcher, J.;
Sobotka, M.
2017psio.confE.105B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Flare induced changes of the photospheric magnetic field in
a delta-spot deduced from ground-based observations
Authors: Gömöry, P.; Balthasar, H.; Kuckein, C.; Koza, J.;
Kuĉera, A.; González Manrique, S. J.; Schwartz, P.; Veronig, A. M.;
Hanslmeier, A.
2017psio.confE.107G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: High-resolution observations of emerging flux regions
Authors: Gonzalez Manrique, Sergio Javier
2017PhDT.......251G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Spectropolarimetric observations of an arch filament system
with the GREGOR solar telescope
Authors: Balthasar, H.; Gömöry, P.; González Manrique, S. J.;
Kuckein, C.; Kavka, J.; Kučera, A.; Schwartz, P.; Vašková, R.;
Berkefeld, T.; Collados Vera, M.; Denker, C.; Feller, A.; Hofmann,
A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pastor Yabar, A.;
Rezaei, R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth,
M.; Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier,
K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
2016AN....337.1050B Altcode: 2016arXiv160901514B
Arch filament systems occur in active sunspot groups, where a fibril
structure connects areas of opposite magnetic polarity, in contrast to
active region filaments that follow the polarity inversion line. We
used the GREGOR Infrared Spectrograph (GRIS) to obtain the full
Stokes vector in the spectral lines Si I λ1082.7 nm, He I λ1083.0
nm, and Ca I λ1083.9 nm. We focus on the near-infrared calcium line
to investigate the photospheric magnetic field and velocities, and
use the line core intensities and velocities of the helium line to
study the chromospheric plasma. The individual fibrils of the arch
filament system connect the sunspot with patches of magnetic polarity
opposite to that of the spot. These patches do not necessarily coincide
with pores, where the magnetic field is strongest. Instead, areas are
preferred not far from the polarity inversion line. These areas exhibit
photospheric downflows of moderate velocity, but significantly higher
downflows of up to 30 km s<SUP>-1</SUP> in the chromospheric helium
line. Our findings can be explained with new emerging flux where the
matter flows downward along the field lines of rising flux tubes,
in agreement with earlier results.
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Title: Horizontal flow fields in and around a small active region. The
transition period between flux emergence and decay
Authors: Verma, M.; Denker, C.; Balthasar, H.; Kuckein, C.; González
Manrique, S. J.; Sobotka, M.; Bello González, N.; Hoch, S.; Diercke,
A.; Kummerow, P.; Berkefeld, T.; Collados, M.; Feller, A.; Hofmann,
A.; Kneer, F.; Lagg, A.; Löhner-Böttcher, J.; Nicklas, H.; Pastor
Yabar, A.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Schubert,
M.; Sigwarth, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier,
K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
2016A&A...596A...3V Altcode: 2016arXiv160507462V
Context. The solar magnetic field is responsible for all aspects
of solar activity. Thus, emergence of magnetic flux at the surface
is the first manifestation of the ensuing solar activity. <BR />
Aims: Combining high-resolution and synoptic observations aims to
provide a comprehensive description of flux emergence at photospheric
level and of the growth process that eventually leads to a mature
active region. <BR /> Methods: The small active region NOAA 12118
emerged on 2014 July 17 and was observed one day later with the 1.5-m
GREGOR solar telescope on 2014 July 18. High-resolution time-series
of blue continuum and G-band images acquired in the blue imaging
channel (BIC) of the GREGOR Fabry-Pérot Interferometer (GFPI) were
complemented by synoptic line-of-sight magnetograms and continuum
images obtained with the Helioseismic and Magnetic Imager (HMI) onboard
the Solar Dynamics Observatory (SDO). Horizontal proper motions and
horizontal plasma velocities were computed with local correlation
tracking (LCT) and the differential affine velocity estimator (DAVE),
respectively. Morphological image processing was employed to measure
the photometric and magnetic area, magnetic flux, and the separation
profile of the emerging flux region during its evolution. <BR />
Results: The computed growth rates for photometric area, magnetic
area, and magnetic flux are about twice as high as the respective
decay rates. The space-time diagram using HMI magnetograms of five days
provides a comprehensive view of growth and decay. It traces a leaf-like
structure, which is determined by the initial separation of the two
polarities, a rapid expansion phase, a time when the spread stalls,
and a period when the region slowly shrinks again. The separation
rate of 0.26 km s<SUP>-1</SUP> is highest in the initial stage, and
it decreases when the separation comes to a halt. Horizontal plasma
velocities computed at four evolutionary stages indicate a changing
pattern of inflows. In LCT maps we find persistent flow patterns such
as outward motions in the outer part of the two major pores, a diverging
feature near the trailing pore marking the site of upwelling plasma and
flux emergence, and low velocities in the interior of dark pores. We
detected many elongated rapidly expanding granules between the two
major polarities, with dimensions twice as large as the normal granules.
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Title: Solar physics at the Einstein Tower
Authors: Denker, C.; Heibel, C.; Rendtel, J.; Arlt, K.; Balthasar,
Juergen H.; Diercke, A.; González Manrique, S. J.; Hofmann, A.;
Kuckein, C.; Önel, H.; Senthamizh Pavai, V.; Staude, J.; Verman, M.
2016AN....337.1105D Altcode: 2016arXiv160906949D
The solar observatory Einstein Tower ({Einsteinturm}) at the
Telegrafenberg in Potsdam is both a landmark of modern architecture
and an important place for solar physics. Originally built for
high-resolution spectroscopy and measuring the gravitational redshift,
research shifted over the years to understanding the active Sun and
its magnetic field. Nowadays, telescope and spectrographs are used for
research and development, i.e., testing instruments and in particular
polarization optics for advanced instrumentation deployed at major
European and international astronomical and solar telescopes. In
addition, the Einstein Tower is used for educating and training of the
next generation astrophysicists as well as for education and public
outreach activities directed at the general public. This article
comments on the observatory's unique architecture and the challenges
of maintaining and conserving the building. It describes in detail the
characteristics of telescope, spectrographs, and imagers; it portrays
some of the research and development activities.
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Title: Flow and magnetic field properties in the trailing sunspots
of active region NOAA 12396
Authors: Verma, M.; Denker, C.; Böhm, F.; Balthasar, H.; Fischer,
C. E.; Kuckein, C.; Bello González, N.; Berkefeld, T.; Collados,
M.; Diercke, A.; Feller, A.; González Manrique, S. J.; Hofmann, A.;
Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pator Yabar, A.; Rezaei,
R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.;
Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier,
K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
2016AN....337.1090V Altcode:
Improved measurements of the photospheric and chromospheric
three-dimensional magnetic and flow fields are crucial for a precise
determination of the origin and evolution of active regions. We present
an illustrative sample of multi-instrument data acquired during a
two-week coordinated observing campaign in August 2015 involving,
among others, the GREGOR solar telescope (imaging and near-infrared
spectroscopy) and the space missions Solar Dynamics Observatory (SDO)
and Interface Region Imaging Spectrograph (IRIS). The observations
focused on the trailing part of active region NOAA 12396 with complex
polarity inversion lines and strong intrusions of opposite polarity
flux. The GREGOR Infrared Spectrograph (GRIS) provided Stokes IQUV
spectral profiles in the photospheric Si I λ1082.7 nm line, the
chromospheric He I λ1083.0 nm triplet, and the photospheric Ca I
λ1083.9 nm line. Carefully calibrated GRIS scans of the active region
provided maps of Doppler velocity and magnetic field at different
atmospheric heights. We compare quick-look maps with those obtained
with the “Stokes Inversions based on Response functions” (SIR)
code, which furnishes deeper insight into the magnetic properties
of the region. We find supporting evidence that newly emerging flux
and intruding opposite polarity flux are hampering the formation
of penumbrae, i.e., a penumbra fully surrounding a sunspot is only
expected after cessation of flux emergence in proximity to the sunspots.
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Title: Inference of magnetic fields in the very quiet Sun
Authors: Martínez González, M. J.; Pastor Yabar, A.; Lagg, A.;
Asensio Ramos, A.; Collados, M.; Solanki, S. K.; Balthasar, H.;
Berkefeld, T.; Denker, C.; Doerr, H. P.; Feller, A.; Franz, M.;
González Manrique, S. J.; Hofmann, A.; Kneer, F.; Kuckein, C.;
Louis, R.; von der Lühe, O.; Nicklas, H.; Orozco, D.; Rezaei, R.;
Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka,
M.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Verma, M.; Waldman,
T.; Volkmer, R.
2016A&A...596A...5M Altcode: 2018arXiv180410089M
Context. Over the past 20 yr, the quietest areas of the solar surface
have revealed a weak but extremely dynamic magnetism occurring
at small scales (<500 km), which may provide an important
contribution to the dynamics and energetics of the outer layers of
the atmosphere. Understanding this magnetism requires the inference
of physical quantities from high-sensitivity spectro-polarimetric
data with high spatio-temporal resolution. <BR /> Aims: We present
high-precision spectro-polarimetric data with high spatial resolution
(0.4”) of the very quiet Sun at 1.56 μm obtained with the GREGOR
telescope to shed some light on this complex magnetism. <BR /> Methods:
We used inversion techniques in two main approaches. First, we assumed
that the observed profiles can be reproduced with a constant magnetic
field atmosphere embedded in a field-free medium. Second, we assumed
that the resolution element has a substructure with either two constant
magnetic atmospheres or a single magnetic atmosphere with gradients of
the physical quantities along the optical depth, both coexisting with
a global stray-light component. <BR /> Results: Half of our observed
quiet-Sun region is better explained by magnetic substructure within
the resolution element. However, we cannot distinguish whether this
substructure comes from gradients of the physical parameters along the
line of sight or from horizontal gradients (across the surface). In
these pixels, a model with two magnetic components is preferred, and
we find two distinct magnetic field populations. The population with
the larger filling factor has very weak ( 150 G) horizontal fields
similar to those obtained in previous works. We demonstrate that the
field vector of this population is not constrained by the observations,
given the spatial resolution and polarimetric accuracy of our data. The
topology of the other component with the smaller filling factor is
constrained by the observations for field strengths above 250 G:
we infer hG fields with inclinations and azimuth values compatible
with an isotropic distribution. The filling factors are typically
below 30%. We also find that the flux of the two polarities is not
balanced. From the other half of the observed quiet-Sun area 50% are
two-lobed Stokes V profiles, meaning that 23% of the field of view
can be adequately explained with a single constant magnetic field
embedded in a non-magnetic atmosphere. The magnetic field vector and
filling factor are reliable inferred in only 50% based on the regular
profiles. Therefore, 12% of the field of view harbour hG fields with
filling factors typically below 30%. At our present spatial resolution,
70% of the pixels apparently are non-magnetised.
---------------------------------------------------------
Title: Fitting peculiar spectral profiles in He I 10830Å absorption
features
Authors: González Manrique, S. J.; Kuckein, C.; Pastor Yabar, A.;
Collados, M.; Denker, C.; Fischer, C. E.; Gömöry, P.; Diercke, A.;
Bello González, N.; Schlichenmaier, R.; Balthasar, H.; Berkefeld, T.;
Feller, A.; Hoch, S.; Hofmann, A.; Kneer, F.; Lagg, A.; Nicklas, H.;
Orozco Suárez, D.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka,
M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Verma,
M.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
2016AN....337.1057G Altcode: 2016arXiv160300679G
The new generation of solar instruments provides better
spectral, spatial, and temporal resolution for a better
understanding of the physical processes that take place on the
Sun. Multiple-component profiles are more commonly observed with these
instruments. Particularly, the He I 10830 Å triplet presents such
peculiar spectral profiles, which give information on the velocity
and magnetic fine structure of the upper chromosphere. The purpose
of this investigation is to describe a technique to efficiently fit
the two blended components of the He I 10830 Å triplet, which are
commonly observed when two atmospheric components are located within
the same resolution element. The observations used in this study were
taken on 2015 April 17 with the very fast spectroscopic mode of the
GREGOR Infrared Spectrograph (GRIS) attached to the 1.5-m GREGOR solar
telescope, located at the Observatorio del Teide, Tenerife, Spain. We
apply a double-Lorentzian fitting technique using Levenberg-Marquardt
least-squares minimization. This technique is very simple and much
faster than inversion codes. Line-of-sight Doppler velocities can
be inferred for a whole map of pixels within just a few minutes. Our
results show sub- and supersonic downflow velocities of up to 32 km
s<SUP>-1</SUP> for the fast component in the vicinity of footpoints of
filamentary structures. The slow component presents velocities close
to rest.
---------------------------------------------------------
Title: Flows in and around Active Region NOAA12118 Observed with
the GREGOR Solar Telescope and SDO/HMI
Authors: Verma, M.; Denker, C.; Balthasar, H.; Kuckein, C.; González
Manrique, S. J.; Sobotka, M.; Bello González, N.; Hoch, S.; Diercke,
A.; Kummerow, P.; Berkefeld, T.; Collados, M.; Feller, A.; Hofmann,
A.; Kneer, F.; Lagg, A.; Löhner-Böttcher, J.; Nicklas, H.; Pastor
Yabar, A.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Schubert,
M.; Sigwarth, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier,
K.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
2016ASPC..504...29V Altcode: 2016arXiv160301109V
Accurate measurements of magnetic and velocity fields in and around
solar active regions are key to unlocking the mysteries of the
formation and the decay of sunspots. High spatial resolution images
and spectral sequences with a high cadence obtained with the GREGOR
solar telescope give us an opportunity to scrutinize 3-D flow fields
with local correlation tracking and imaging spectroscopy. We present
GREGOR early science data acquired in 2014 July - August with the GREGOR
Fabry-Pérot Interferometer and the Blue Imaging Channel. Time-series
of blue continuum (λ 450.6 nm) images of the small active region
NOAA 12118 were restored with the speckle masking technique to derive
horizontal proper motions and to track the evolution of morphological
changes. In addition, high-resolution observations are discussed in
the context of synoptic data from the Solar Dynamics Observatory.
