Spectropolarimetric observations of the solar atmosphere in the H alpha 6563 angstrom line

0556498 - ASÚ 2023 RIV FR eng J - Journal Article
Jaume Bestard, J. - Trujillo Bueno, J. - Bianda, M. - Štěpán, Jiří - Ramelli, R.
Spectropolarimetric observations of the solar atmosphere in the H alpha 6563 angstrom line.
Astronomy & Astrophysics. Roč. 659, March (2022), č. článku A179. ISSN 0004-6361. E-ISSN 1432-0746
R&D Projects: GA ČR(CZ) GA19-20632S
Institutional support: RVO:67985815
Keywords : impact polarization * hydrogen * telescope
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 6.5, year: 2022
Method of publishing: Open access with time embargo
https://doi.org/10.1051/0004-6361/202141834

We present novel spectropolarimetric observations of the hydrogen H alpha line taken with the Zurich Imaging Polarimeter (ZIMPOL) at the Gregory Coude Telescope of the Istituto Ricerche Solari Locarno (IRSOL). The linear polarization is clearly dominated by the scattering of anisotropic radiation and the Hanle effect, while the circular polarization is dominated by the Zeeman effect. The observed linear polarization signals show a rich spatial variability, the interpretation of which would open a new window for probing the solar chromosphere. We study their spatial variation within coronal holes, finding a different behaviour for the U/I signals near the north and south solar poles. We identify some spatial patterns, which may facilitate the interpretation of the observations. In close-to-the-limb regions with sizable circular polarization signals, we find similar asymmetric Q/I profiles. We also show examples of net circular polarization profiles (NCP), along with the corresponding linear polarization signals. The application of the weak field approximation to the observed circular polarization signals gives 10 G (40-60 G) close to the limb quiet (plage) regions for the average longitudinal field strength over the spatio-temporal resolution element.
Permanent Link: http://hdl.handle.net/11104/0330916