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Author name code: caligari
ADS astronomy entries on 2022-09-14
author:"Caligari, Peter"
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Title: A retrospective of the GREGOR solar telescope in scientific
literature
Authors: Denker, C.; von der Lühe, O.; Feller, A.; Arlt, K.;
Balthasar, H.; Bauer, S. -M.; Bello González, N.; Berkefeld, Th.;
Caligari, P.; Collados, M.; Fischer, A.; Granzer, T.; Hahn, T.;
Halbgewachs, C.; Heidecke, F.; Hofmann, A.; Kentischer, T.; Klva{ňa,
M.; Kneer, F.; Lagg, A.; Nicklas, H.; Popow, E.; Puschmann, K. G.;
Rendtel, J.; Schmidt, D.; Schmidt, W.; Sobotka, M.; Solanki, S. K.;
Soltau, D.; Staude, J.; Strassmeier, K. G.; Volkmer, R.; Waldmann,
T.; Wiehr, E.; Wittmann, A. D.; Woche, M.
2012AN....333..810D Altcode: 2012arXiv1210.3167D
In this review, we look back upon the literature, which had the
GREGOR solar telescope project as its subject including science cases,
telescope subsystems, and post-focus instruments. The articles date
back to the year 2000, when the initial concepts for a new solar
telescope on Tenerife were first presented at scientific meetings. This
comprehensive bibliography contains literature until the year 2012,
i.e., the final stages of commissioning and science verification. Taking
stock of the various publications in peer-reviewed journals and
conference proceedings also provides the “historical” context
for the reference articles in this special issue of Astronomische
Nachrichten/Astronomical Notes.
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Title: The GREGOR telescope control system
Authors: Halbgewachs, C.; Caligari, P.; Glogowski, K.; Heidecke, F.;
Knobloch, M.; Mustedanagic, M.; Volkmer, R.; Waldmann, T. A.
2012AN....333..840H Altcode:
This article describes the architecture of the new GREGOR telescope
and its instrument control system. A short summary is given on the
communication structure between instruments and other devices during
observation. Because of its importance to all instruments the main
functions of the telescope control system are described in detail.
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Title: GREGOR telescope: start of commissioning
Authors: Volkmer, R.; von der Lühe, O.; Denker, C.; Solanki, S.;
Balthasar, H.; Berkefeld, T.; Caligari, P.; Collados, M.; Halbgewachs,
C.; Heidecke, F.; Hofmann, A.; Klvana, M.; Kneer, F.; Lagg, A.; Popow,
E.; Schmidt, D.; Schmidt, W.; Sobotka, M.; Soltau, D.; Strassmeier, K.
2010SPIE.7733E..0KV Altcode: 2010SPIE.7733E..18V
With the integration of a 1-meter Cesic primary mirror the GREGOR
telescope pre-commissioning started. This is the first time, that
the entire light path has seen sunlight. The pre-commissioning period
includes testing of the main optics, adaptive optics, cooling system,
and pointing system. This time was also used to install a near-infrared
grating spectro-polarimeter and a 2D-spectropolarimeter for the visible
range as first-light science instruments. As soon as the final 1.5
meter primary mirror is installed, commissioning will be completed,
and an extended phase of science verification will follow. In the near
future, GREGOR will be equipped with a multi-conjugate adaptive optics
system that is presently under development at KIS.
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Title: GREGOR solar telescope: Design and status
Authors: Volkmer, R.; von der Lühe, O.; Denker, C.; Solanki, S. K.;
Balthasar, H.; Berkefeld, T.; Caligari, P.; Collados, M.; Fischer, A.;
Halbgewachs, C.; Heidecke, F.; Hofmann, A.; Klvaňa, M.; Kneer, F.;
Lagg, A.; Popow, E.; Schmidt, D.; Schmidt, W.; Sobotka, M.; Soltau,
D.; Strassmeier, K. G.
2010AN....331..624V Altcode:
The integration and verification phase of the GREGOR telescope
reached an important milestone with the installation of the
interim 1 m SolarLite primary mirror. This was the first time
that the entire light path had seen sunlight. Since then extensive
testing of the telescope and its subsystems has been carried out. The
integration and verification phase will culminate with the delivery and
installation of the final 1.5 m Zerodur primary mirror in the summer of
2010. Observatory level tests and science verification will commence in
the second half of 2010 and in 2011. This phase includes testing of the
main optics, adaptive optics, cooling and pointing systems. In addition,
assuming the viewpoint of a typical user, various observational modes
of the GREGOR Fabry-Pérot Interferometer (GFPI), the Grating Infrared
Spectrograph (GRIS), and high-speed camera systems will be tested to
evaluate if they match the expectations and science requirements. This
ensures that GREGOR will provide high-quality observations with its
combination of (multi-conjugate) adaptive optics and advanced post-focus
instruments. Routine observations are expected for 2012.
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Title: The control and data concept for the robotic solar telescope
ChroTel
Authors: Halbgewachs, C.; Bethge, Ch.; Caligari, P.; Elmore, D.;
Kentischer, T. J.; Peter, H.; Sigwarth, M.; Schmidt, W.
2008SPIE.7019E..2TH Altcode: 2008SPIE.7019E..93H
The solar telescope ChroTel is designed as a robotic telescope so
that no user interaction is necessary for observation. The telescope
will start tracking in the morning as soon as weather conditions are
appropriate and will process a user defined observation routine until
sunset. Weather conditions and system status are continuously monitored
to close the telescope shutter in case of bad weather or to drive to
the stow position in case of an error. The ChroTel control software
was programmed in LabVIEW.
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Title: GREGOR: the New German Solar Telescope
Authors: Balthasar, H.; von der Lühe, O.; Kneer, F.; Staude, J.;
Volkmer, R.; Berkefeld, T.; Caligari, P.; Collados, M.; Halbgewachs,
C.; Heidecke, F.; Hofmann, A.; Klvaňa, M.; Nicklas, H.; Popow, E.;
Puschmann, K.; Schmidt, W.; Sobotka, M.; Soltau, D.; Strassmeier,
K.; Wittmann, A.
2007ASPC..368..605B Altcode: 2007arXiv0704.2693B
GREGOR is a new open solar telescope with an aperture of 1.5 m. It
replaces the former 45-cm Gregory Coudé telescope on the Canary island
Tenerife. The optical concept is that of a double Gregory system. The
main and the elliptical mirrors are made from a silicon-carbide material
with high thermal conductivity. This is important to keep the mirrors
on the ambient temperature avoiding local turbulence. GREGOR will be
equipped with an adaptive optics system. The new telescope will be ready
for operation in 2008. Post-focus instruments in the first stage will be
a spectrograph for polarimetry in the near infrared and a 2-dimensional
spectrometer based on Fabry-Pérot interferometers for the visible.
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Title: New high resolution solar telescope GREGOR
Authors: Volkmer, R.; von der Lühe, O.; Kneer, F.; Staude, J.;
Balthasar, H.; Berkefeld, T.; Caligari, P.; Collados, M.; Halbgewachs,
C.; Heidecke, F.; Hofmann, A.; Klvaña, M.; Sobotka, M.; Nicklas, H.;
Popow, E.; Puschmann, K. G.; Schmidt, W.; Soltau, D.; Strassmeier,
K.; Wittmann, A. D.
2007msfa.conf...39V Altcode:
The 1.5m solar telescope GREGOR is being constructed at Tenerife,
Spain. Its purpose is to observe with high spatial and spectral
resolution small-scale dynamic magnetic features on the Sun. The
telescope is completely open with retractable dome and actively cooled
primary mirror made of silicon carbide to minimize thermal effects
on the image quality. After completion it will be one of the most
powerful solar telescopes. This paper presents a general overview of
the telescope characteristics and the current status.
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Title: The new 1.5m solar telescope GREGOR: first light and start
of commissioning
Authors: Volkmer, Reiner; von der Lühe, Oskar; Kneer, Franz; Staude,
Jürgen; Berkefeld, Thomas; Caligari, Peter; Halbgewachs, Clemens;
Heidecke, Frank; Schmidt, Wolfgang; Soltau, Dirk; Nicklas, Harald;
Wittmann, Axel; Balthasar, Horst; Hofmann, Axel; Strassmeier, Klaus;
Sobotka, Michal; Klvana, Miroslav; Collados, Manuel
2006SPIE.6267E..0WV Altcode: 2006SPIE.6267E..29V
The integration of the three main silicon carbide mirrors into the new
1.5 m solar telescope GREGOR at Izana on Tenerife, Spain is planned
during 2006. We expect first light at the end of 2006. A progress
report about integration of the optics and mechanics and planning of
the commissioning phase of the telescope and post focus instruments
will be presented at the meeting. The GREGOR telescope is build by a
consortium of the Kiepenheuer Institut fur Sonnenphysik in Freiburg,
the Astrophysikalische Institut Potsdam, the Institut fur Astronomie
Gottingen and additional national and international Partners.
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Title: The new 1.5 solar telescope GREGOR: progress report and
results of performance tests
Authors: Volkmer, Reiner; von der Lühe, Oskar; Kneer, Franz; Staude,
Jürgen; Berkefeld, Thomas; Caligari, Peter; Halbgewachs, Clemens;
Schmidt, Wolfgang; Soltau, Dirk; Nicklas, Harald; Wittmann, Axel;
Balthasar, Horst; Hofmann, Axel; Strassmeier, Klaus; Sobotka, Michal;
Klvana, Miroslav; Collados, Manuel
2005SPIE.5901...75V Altcode:
The telescope structure including control system and the complete
retractable dome of the new 1.5 m solar telescope GREGOR were
assembled during 2004 at Izana on Tenerife, Spain. The GREGOR
telescope is build by a consortium of the Kiepenheuer Institut fuer
Sonnenphysik, the Astrophysikalische Institut Potsdam, the Institut
fuer Astrophysik Goettingen and additional national and international
Partners. Pointing, tracking and thermal tests were made to verify
the proposed performance. The results of these tests and a progress
report of the project will be presented.
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Title: Progress report of the 1.5 m solar telescope GREGOR
Authors: Volkmer, Reiner; von der Lühe, Oskar F.; Kneer, Franz;
Staude, Jürgen; Berkefeld, Thomas; Caligari, Peter; Schmidt,
Wolfgang; Soltau, Dirk; Nicklas, Harald; Wiehr, Eberhardt; Wittmann,
Axel; Balthasar, Horst; Hofmann, Axel; Strassmeier, Klaus; Sobotka,
Michal; Klvana, Miroslav; Collados, Manuel
2004SPIE.5489..693V Altcode:
GREGOR is the new 1.5 m solar telescope assembled on Tenerife, Spain, by
the German consortium of the Kiepenheuer Institut fur Sonnenphysik, the
Astronomischen Institut Potsdam, the Universitats-Sternwarte Gottingen
and other national and international Partners. The refurbishment of
the building is almost finished. The manufacturing of the telescope
structure and the optics is still in progress. After the integration of
the new complete retractable dome in July 2004 the telescope structure,
optic and post focus instruments will be assembled during the rest of
the year. First light is planned during May 2005.
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Title: Star Spot Patterns on Young Stars: Theoretical Approach
(CD-ROM Directory: contribs/granzer2)
Authors: Granzer, Th.; Caligari, P.; Schüssler, M.; Strassmeier, K. G.
2001ASPC..223.1232G Altcode: 2001csss...11.1232G
No abstract at ADS
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Title: Distribution of starspots on cool stars. II. Pre-main-sequence
and ZAMS stars between 0.4 M<SUB>sun</SUB> and 1.7 M<SUB>sun</SUB>
Authors: Granzer, Th.; Schüssler, M.; Caligari, P.; Strassmeier, K. G.
2000A&A...355.1087G Altcode:
We study the dynamics of magnetic flux tubes in young stars with masses
between 0.4 M<SUB>sun</SUB> and 1.7 M<SUB>sun</SUB> and for rotation
rates between 0.25 Omega<SUB>sun</SUB> and 63 Omega<SUB>sun</SUB>
. The resulting latitudinal emergence patterns at the stellar
surface are compared with observed distributions of starspots in
stellar latitude. The stellar models considered cover the range of
evolutionary stages from shortly after the Hayashi phase down to
the ZAMS, i.e. from the classical and weak-line T Tauri stars to
the alpha -Persei stars. We use numerical simulations to follow the
evolution of magnetic flux tubes from their origin at the bottom of the
convection zone up to near-surface layers. We find a strong increase of
emergence latitude with increasing rotation rate, a moderate decrease
with increasing stellar mass, and a stronger decrease with stellar
age. At very early evolutionary stages, when the central radiative
zone is still quite small, we find magnetic flux emergence both in
low latitudes as well as in the polar areas. High-latitude emergence
is predicted in slightly more evolved pre-main-sequence and young
main-sequence stars, but truly polar spots on these stars require an
additional transport mechanism acting after magnetic flux emergence at
the surface, probably meridional circulation or poleward slip of the
`anchored' part of the erupted flux tubes. We discuss our findings in
the light of the results obtained from Doppler-imaging studies.
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Title: Emerging Flux Tubes in the Solar Convection Zone. II. The
Influence of Initial Conditions
Authors: Caligari, P.; Schüssler, M.; Moreno-Insertis, F.
1998ApJ...502..481C Altcode:
Numerical simulations of rising magnetic flux tubes in the solar
convection zone have contributed significantly to our understanding
of the basic properties of sunspot groups. They have provided an
important clue to the operation of the solar dynamo by predicting
strong (super-equipartition) magnetic fields near the bottom of the
convection zone. We have investigated to what extent the simulation
results (obtained on the basis of the thin flux tube approximation)
depend on the assumptions made about the initial state of a magnetic
flux tube at the start of the simulation. Two initial conditions used in
the literature have been considered in detail: mechanical equilibrium
(MEQ) and temperature balance (TBL). It turns out that the requirement
of super-equipartition field strength is a robust feature of the
simulations, largely independent of the choice of initial conditions:
emergence of active regions at low latitudes and the correct dependence
of their tilt angle (with respect to the east-west direction) as a
function of heliographic latitude require an initial magnetic field
strength on the order of 10<SUP>5</SUP> G. Other properties of rising
flux tubes, such as the asymmetries of shape and field strength between
the leading and following wings (with respect to the direction of
rotation) of a rising loop, or the anchoring of part of the flux tube
in the overshoot region, depend on the initial condition. Observed
asymmetries in the magnetic flux distribution and of proper motions
in emerging active regions favor MEQ over TBL as the proper initial
condition. MEQ should also be preferred for other theoretical reasons:
it allows for fewer free parameters, it requires no fine tuning for the
tube geometry and background stratification in the overshoot region,
and it can be easily made compatible with an encompassing model of the
generation, storage, and eruption of the magnetic flux. We have also
studied whether an external upflow (convective updraft) can trigger
the eruption of an otherwise stably stored flux tube in the overshoot
region. We find that a significant deformation and destabilization of
a flux tube with equipartition field strength requires coherent upflow
velocities of 20-50 m s<SUP>-1</SUP> in the overshoot layer, which is
an order of magnitude larger than current estimates for such velocities.
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Title: Predicted Starspot Distributions on Pre-MS Stars
Authors: Granzer, Th.; Strassmeier, K. G.; Schussler, M.; Caligari, P.
1998ASPC..154.1977G Altcode: 1998csss...10.1977G
We present an application of the magnetic flux-tube model of Caligari
(1995, 1991) to pre-main-sequence stars. This model was originally
designed as an explanation for sunspots. The primary goal is to
derive the emerging latitude of flux tubes for a large parameter
volume including stellar mass, age, and rotational period. Since the
original model worked well in explaining certain sunspot features,
the next step would be to compare our model predictions with observed
starspot distributions obtained by Doppler imaging techniques.
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Title: Origin of the Proper Motions of Emerging Bipolar Magnetic
Regions
Authors: Caligari, P.; Schussler, M.; Moreno-Insertis, F.
1997ASPC..118...76C Altcode: 1997fasp.conf...76C
We have performed numerical simulations of the rise of magnetic
flux tubes through the convection zone. We find that the observed
proper motions of pores and sunspots in young active regions can
be understood as a consequence of the Coriolis force: conservation
of angular momentum leads to a retardation of the rising flux loop
with respect to those parts of the flux tube that remain anchored in
the overshoot layer below the convection zone proper. The result is
an asymmetric shape with the following flank of the loop being more
vertical than the leading part. When emerging at the solar surface,
the asymmetric shape of the tube leads to proper motions which are
in qualitative agreement with the observations. By studying the
dependence of the asymmetry on the initial state of the flux tube we
find that the observed proper motions favor a mechanical equilibrium
of the magnetic field in the overshoot layer. We also find that small
active regions (emerging from flux tubes with little magnetic flux)
are less asymmetric and should show weaker proper motions than large
bipolar regions. This prediction can be put to an observational test.
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Title: Distribution of starspots on cool stars. I. Young and main
sequence stars of 1M<SUB>sun</SUB>_.
Authors: Schuessler, M.; Caligari, P.; Ferriz-Mas, A.; Solanki, S. K.;
Stix, M.
1996A&A...314..503S Altcode:
Sunspots are restricted to a latitude band within 30degof the solar
equator. In contrast, the latitudes of spots on the surfaces of
rapidly rotating cool stars can range from their polar regions, for
RS CVn systems and for T Tauri stars leaving the Hayashi track, to
mid latitudes for stars close to or on the main sequence. In order to
find an explanation for these observed spot latitudes we have applied
the criteria for the undulatory instability (Parker instability) of
a toroidal magnetic flux tube embedded in the convective overshoot
layer below the outer convection zone and calculated the non-linear
evolution of the rising magnetic loops formed by this instability. We
describe the results for a star of one solar mass in different phases
of its evolution before and on the main sequence. We find that there
usually is a range of latitudes at which magnetic flux can emerge on
the stellar surface. The mean latitude of emergence shifts towards
the poles for increasingly rapid rotation. The internal structure
of the star, however, plays an almost equally important role in
determining the latitude of magnetic emergence. For stars of solar
mass only the youngest objects, with extremely deep convection zones,
should show spots emerging at the stellar poles. Pre-main sequence
stars at an age of 10^7^ y (convection zone reaching down half-way to
the centre) exhibit high latitude, but not truly polar spots, while
a main sequence star of one solar mass, even at high rotation rates,
only shows intermediate latitude spots. These results are found to be
in good agreement with Doppler images of young rapid rotators.
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Title: Flux Tube Dynamics in Active Stars
Authors: Caligari, P.; Schüssler, M.; Solanki, S. K.; Schaerer, D.;
Stix, M.
1996ApL&C..34...17C Altcode:
No abstract at ADS
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Title: “Explosion” and Intensification of Magnetic Flux Tubes
Authors: Moreno-Insertis, F.; Caligari, P.; Schuessler, M.
1995ApJ...452..894M Altcode:
A magnetic flux tube anchored at the bottom of the solar convection
zone and rising toward the surface as a result of an undulatory
instability can be affected by a sudden catastrophic expansion and
weakening of the magnetic field at its apex if the original field
strength is below a few times 10<SUP>4</SUP> G. Such an "explosion"
occurs if the flux tube evolves close enough to (adiabatic) hydrostatic
equilibrium along the magnetic field lines in a super-adiabatically
stratified environment. This condition is satisfied if the diameter of
the tube is small enough for the drag force to dominate the dynamical
evolution. For example, rising flux tubes with equipartition field
(10<SUP>4</SUP> G) at their basis explode in the middle of the
convection zone if their magnetic flux is below ≌10<SUP>21</SUP>
Mx. <P />Apart from preventing flux tubes with equipartition field
from reaching the surface, the explosion process may have other
consequences for the evolution of magnetic fields in the convection
zone: (a) it provides a source of weak field to be acted upon by
the convective flows in the course of a turbulent dynamo process;
(b) upflow of matter into the inflated top of a loop intensifies the
magnetic field in the submerged part of the flux tube at the bottom of
the convection zone. This might constitute a mechanism to produce the
strong azimuthal fields in the overshoot region suggested by recent
studies of the undular instability of magnetic flux tubes.
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Title: Emerging Flux Tubes in the Solar Convection Zone. I. Asymmetry,
Tilt, and Emergence Latitude
Authors: Caligari, P.; Moreno-Insertis, F.; Schussler, M.
1995ApJ...441..886C Altcode:
The process of emergence of magnetic flux from the depths of the
convection zone to the surface is presented in the framework of
self-consistent model for the storage of field in the lower overshoot
regions and as the mechanism responsible for some of the regularities
observed in active regions. We have performed numerical simulations
of the emergence of flux tubes in the solar convection zone including
the effects of spherical geometry and rotation. The magnetic flux
tubes can be stored in mechanical equilibrium in the overshoot region,
which is the natural equilibrium of the flux rings in a subadiabatic
layer. An undular instability leads to the formation of loops once
a critical magnetic field strength of the order of 10<SUP>5</SUP>
G is exceeded. In the nonlinear phase of their unstable evolution,
the tubes move across the convection zone on a very fast time-scale,
typically about one month. The geometry and dynamics of the flux tubes
studied in these simulations permit prediction of some of the observed
properties of the active regions. First, the wings of the tube show a
marked asymmetry of inclination and velocity, which is compatible with
the observed asymmetric proper motions of sunspots and with the position
of the neutral line in emerging active regions. Second, upon emergence
the flux tubes show a tilt angle with respect to the equator which
fits reasonably well with the observed values. Third, the flux tubes
rise roughly within a cone of radial directions in the Sun so that no
outbreak at high latitudes takes place. The calculations lend further
support to the possibility of superequipartition field strengths in the
overshoot region. The implications of the present results for the dynamo
mechanism are discussed and hints for observational work are also given.
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Title: Observation of Surface Activity on Cool Giants with the VLT
Interferometer
Authors: von der Lühe, O.; Schüssler, M.; Solanki, S. K.; Caligari,
P.
1995svlt.conf...94V Altcode:
No abstract at ADS
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Title: Active Region Asymmetry as a Result of the Rise of Magnetic
Flux Tubes
Authors: Moreno-Insertis, F.; Caligari, P.; Schuessler, M.
1994SoPh..153..449M Altcode:
The magnetic flux tubes that rise across the convection zone to produce
active regions are shown to develop a difference in inclination between
their preceding and follower sides. This asymmetry is such that the
follower wing is more vertical (i.e., closer to the radial direction)
than the preceding side. An asymmetry of this kind can be obtained as a
natural consequence of the conservation of angular momentum along the
rise. This process may explain a number of the observed asymmetries
in morphology and behavior of the preceding and follower parts of the
active regions. We present results of numerical simulations showing
this effect and discuss possible observational consequences.
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Title: Distribution of Magnetic Flux on the Surface of Rapidly
Rotating Stars
Authors: Caligari, P.; Schussler, M.; Stix, M.; Solanki, S. K.
1994ASPC...64..387C Altcode: 1994csss....8..387C
No abstract at ADS
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Title: Dynamics of erupting magnetic flux tubes
Authors: Moreno-Insertis, F.; Schüssler, M.; Caligari, P.
1994ASIC..433..407M Altcode: 1994ssm..work..407M
The eruption of magnetic flux tubes from the overshoot layer due to
instability and the dynamics of their subsequent rise through the solar
convection zone are followed by numerical simulation. Special emphasis
is put on the possibility of explaining observed regularities of the
active regions at the surface (tilt angles, latitude of emergence,
asymmetry between preceding and following parts, etc). Instability
sets in with non-axisymmetric (undular) modes at azimuthal wavenumbers
$m=1$ and $m=2$ if the field strength exceeds values of the order of
$10^5$ G. At the same time, such strong initial fields are required
to reproduce the observable properties of sunspots and active
regions. Consequently, a consistent picture of storage, instability
and eruption of solar magnetic fields emerges.
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Title: Instability and eruption of magnetic flux tubes
Authors: Caligari, P.; Ferriz-Mas, A.; Moreno-Insertis, F.;
Schüssler, M.
1994smf..conf..139C Altcode:
No abstract at ADS
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Title: Flux tube dynamics in pre-main-sequence and giant stars.
Authors: Caligari, P.; Schaerer, D.; Schüssler, M.; Solanki, S.
1994AGAb...10...92C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Instability and eruption of magnetic flux tubes in the solar
convection zone.
Authors: Schussler, M.; Caligari, P.; Ferriz-Mas, A.; Moreno-Insertis,
F.
1994A&A...281L..69S Altcode:
We present a consistent model of storage, instability and dynamical
eruption of magnetic flux tubes in the solar convection zone
and underlying overshoot region. Using a convection zone model
with self-consistent overshoot layer, we calculate equilibrium
configurations of magnetic flux tubes and determine their linear
stability properties, taking into consideration the effects of
stratification and rotation. Instability of flux tubes stored in
the overshoot layer with growth times below one year requires field
strengths of the order of 10<SUP>5</SUP> G; in many cases, the dominant
mode has an azimuthal wave number of m = 2. Numerical simulations are
used to follow the nonlinear evolution of such unstable flux tubes and
their rise through the convection zone, from which they emerge to form
active regions. The results are in accordance with the following two
requirements, based on observational facts: (a) the upward motion of
the tubes is not significantly deflected by the Coriolis force so that
they can emerge at low latitudes, (b) their inclination with respect
to the East-West direction (tilt angle) as a function of the latitude
of emergence is consistent with observations of acitve regions.
---------------------------------------------------------
Title: Instability of magnetic flux tubes in the solar convection
zone.
Authors: Caligari, P.; Moreno-Insertis, F.; Schüssler, M.
1992AGAb....7..152C Altcode:
No abstract at ADS
