Issue |
A&A
Volume 410, Number 2, November I 2003
|
|
---|---|---|
Page(s) | 695 - 710 | |
Section | The Sun | |
DOI | https://doi.org/10.1051/0004-6361:20031282 | |
Published online | 17 November 2003 |
Three dimensional structure of a regular sunspot from the inversion of IR Stokes profiles
1
Max-Planck-Institut für Aeronomie, 37191 Katlenburg-Lindau, Germany e-mail: lagg@linmpi.mpg.de, solanki@linmpi.mpg.de, borrero@linmpi.mpg.de, krupp@linmpi.mpg.de, woch@linmpi.mpg.de
2
Instituto de Astrofísica de Canarias, La Laguna, Tenerife, Spain e-mail: mcv@ll.iac.es
3
Institut für Astronomie, ETH, 8092 Zürich, Switzerland e-mail: sveta@astro.phys.ethz.ch, frutiger@astro.phys.ethz.ch
Corresponding author: S. K. Mathew, shibu@ll.iac.es
Received:
7
May
2003
Accepted:
8
August
2003
The magnetic, thermal and velocity structure of a regular sunspot, observed close to
solar disk center is presented. Spectropolarimetric data obtained with the Tenerife
Infrared Polarimeter (TIP) in two infrared Fe I lines at
15 648.5 Åand 15 652.8 Åare inverted employing a technique based on response
functions to retrieve the atmospheric stratification at every point in the sunspot.
In order to improve the results for the umbra, profiles of Zeeman split OH lines
blending the Fe I 15 652.8 Åare also consistently fit.
Thus we obtain maps of temperature, line-of-sight velocity, magnetic field strength,
inclination, and azimuth, as a function of both location within the sunspot and
height in the atmosphere. We present these maps for an optical depth range between
log = 0 and log
, where these lines provide accurate
results. We find decreasing magnetic field strength with increasing height all over
the sunspot, with a particularly large vertical field gradient of ~-4 G km-1 in the umbra. We also observe the so called “spine” structures in the
penumbra, i.e. extended radial features with a stronger and more vertical magnetic
field than the surroundings. Also we found that the magnetic field zenith angle
increases with height. From the velocity map it is clear that the Evershed flow
avoids the spines and mostly concentrates in the more inclined intervening field. The
field inclination at a few locations in the outer penumbra in lower layers goes
beyond 90°. These locations coincide with the strongest flows in the velocity
map.
Key words: Sun: sunspots / Sun: magnetic fields / Sun: infrared / Sun: general
© ESO, 2003
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