Issue |
A&A
Volume 646, February 2021
|
|
---|---|---|
Article Number | A81 | |
Number of page(s) | 6 | |
Section | The Sun and the Heliosphere | |
DOI | https://doi.org/10.1051/0004-6361/202037767 | |
Published online | 10 February 2021 |
Solar activity and responses observed in Balmer lines
1
Science Systems and Applications, Inc., Lanham, MD, USA
e-mail: sergey.marchenko@ssaihq.com
2
Goddard Space Flight Center, Greenbelt, MD, USA
3
National Solar Observatory, Boulder, CO, USA
4
San Fernando Observatory, California State University, Northridge, CA, USA
5
University of Colorado/LASP, Boulder, CO, USA
Received:
18
February
2020
Accepted:
12
December
2020
Context. Many stars show Sun-like magnetic activity cycles, which are frequently observed by tracking changes in the chromospherically sensitive CaII H&K doublet. However, relationships between the line profile changes related to the magnetic activity seen in strong spectral transitions in other portions of a stellar spectrum are yet to be understood.
Aims. We follow variability patterns in various solar lines in order to relate them to the emergence, passage, and decay of active solar regions.
Methods. The line activity indices (core-to-wing ratio) for the upper Balmer lines – Hβ, Hγ, and Hδ – are constructed from the near-daily solar measurements acquired by the Ozone Monitoring Instrument and the TROPOspheric Monitoring Instrument.
Results. On solar rotation timescales, the upper Balmer line activity indices closely follow variations in the total solar irradiance, r ∼ −(0.6 − 0.7), and thus frequently deviate from the behavior of the line activity indices that track chromospheric activity levels (e.g., the CH 430 nm band used in this study), specifically during passages of big sunspot groups.
Key words: Sun: activity / Sun: atmosphere
© S. Marchenko et al. 2021
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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