A Quantitative Comparison of Observed and Theoretical Stokes Profiles of the Ca II 8542 Å Line in the Quiet Sun

0552725 - ASÚ 2022 RIV US eng C - Konferenční příspěvek (zahraniční konf.)
Jurčák, Jan - Štěpán, Jiří - Bianda, M. - Trujillo Bueno, J.
A Quantitative Comparison of Observed and Theoretical Stokes Profiles of the Ca II 8542 Å Line in the Quiet Sun.
Solar Polarization Workshop 8. San Francisco: Astronomical Society of the Pacific, 2019 - (Belluzzi, I.), s. 235-241. ASP Conference Series, 526. ISBN 978-1-58381-939-5. E-ISSN 1050-3390.
[Solar Polarization Workshop 8. Florence (IT), 12.09.2016-16.09.2016]
Grant CEP: GA ČR(CZ) GA16-16861S
Institucionální podpora: RVO:67985815
Klíčová slova: Stokes profiles * spectropolarimetric observations * quantitative comparison
Obor OECD: Astronomy (including astrophysics,space science)

We present an analysis of the Stokes profiles of the Ca II 8542 Å line produced by the joint action of atomic level polarization and the Hanle and Zeeman effects. We compare spectropolarimetric observations of this line in a quiet region at the solar disk centre, taken with the ZIMPOL instrument at IRSOL, with the theoretical Stokes profiles computed with the PORTA radiative transfer code using as solar model atmosphere a 3D snapshot taken from a radiation MHD simulation of an enhanced-network region. Even though the spatial sampling of the ZIMPOL observations is only 1.43 arcsec/pixel, we detect Q/I, U/I and V/I polarization signals of the order of 0.1%. The synthetic line profiles have been obtained by solving the full 3D NLTE radiative transfer problem taking into account the symmetry breaking effects due to the model's horizontal inhomogeneities and macroscopic velocity gradients. After spatial and spectral degradation, in some locations we find similar amplitudes between the observed and calculated linear polarization profiles. However, in general, the observations show stronger polarization signals than the calculated ones, a discrepancy that could be used to refine the numerical models of the quiet solar chromosphere.
Trvalý link: http://hdl.handle.net/11104/0327842