Quiet-Sun hydrogen Lyman-alpha line profile derived from SOHO/SUMER solar-disk observations

0537299 - ASÚ 2021 RIV FR eng J - Článek v odborném periodiku
Gunár, Stanislav - Schwartz, P. - Koza, J. - Heinzel, Petr
Quiet-Sun hydrogen Lyman-alpha line profile derived from SOHO/SUMER solar-disk observations.
Astronomy & Astrophysics. Roč. 644, December (2020), č. článku A109. ISSN 0004-6361. E-ISSN 1432-0746
Grant CEP: GA ČR GA19-16890S; GA ČR(CZ) GA19-17102S; GA ČR(CZ) GA19-20632S
Institucionální podpora: RVO:67985815
Klíčová slova: Sun * UV radiation * filaments
Obor OECD: Astronomy (including astrophysics,space science)
Impakt faktor: 5.803, rok: 2020
Způsob publikování: Omezený přístup
https://doi.org/10.1051/0004-6361/202039348

We derive a reference quiet-Sun Lyman-alpha spectral profile that is representative of the Lyman-alpha radiation from the solar disk during a minimum of solar activity. This profile can serve as an incident radiation boundary condition for the radiative transfer modelling of chromospheric and coronal structures. Because the solar radiation in the Lyman lines is not constant over time but varies significantly with the solar cycle, we provide a method for the adaptation of the incident radiation Lyman line profiles (Lyman-alpha and higher lines) to a specific date. Moreover, we analyse how the change in the incident radiation influences the synthetic spectra produced by the radiative transfer modelling. We present the reference quiet-Sun Lyman-alpha profile and a table of coefficients describing the variation of the Lyman lines with the solar cycle throughout the lifetime of SOHO. The analysis of the influence of the change in the incident radiation shows that the synthetic spectra are strongly affected by the modification of the incident radiation boundary condition. The most pronounced impact is on the central and integrated intensities of the Lyman lines. There, the change in the synthetic spectra can often have the same amplitude as the change in the incident radiation itself. The impact on the specific intensities in the peaks of reversed Lyman-line profiles is smaller but still significant. The hydrogen H alpha line can also be considerably affected, despite the fact that the H alpha radiation from the solar disk does not vary with the solar cycle.
Trvalý link: http://hdl.handle.net/11104/0315028