Starspot mapping and multiwavelength variability for a young solar-type star
Zenodo (CERN European Organization for Nuclear Research)
Abstract
Recent simultaneous multiwavelength observations by the Transiting Exoplanet Survey Satellite (TESS), Seimei telescope, and Neutron star Interior Composition Explorer (NICER), have provided evidence for stellar prominence eruptions associated with superflares on a young solar-type star EK Draconis (EK Dra) (Namekata et al. 2024a). Such superflares are suggested to have been caused by large spots on the polarity inversion line near the stellar limb from the concurrent result of the Zeeman Doppler Imaging (ZDI) at the Bernard Lyot telescope (Namekata et al. 2024b). Thus, to investigate the relation between spot locations from the optical photometry and occurrence of superflares, we perform starspot mapping for the TESS light curve of EK Dra with the code (Ikuta et al. 2020). We also analyze the rotational variability of the TESS light curve, H$\alpha$ spectrum by the Seimei/KOOLS-IFU, and X-ray data by the NICER, each of which corresponds to the stellar photosphere, chromosphere, and stellar atmosphere (corona), respectively. As a result, we find that (i) some spots are deduced to be near the limb when superflares occurred, (ii) spot locations are consistent with those obtained from the ZDI except for a polar spot, and (iii) the H$\alpha$ spectrum produced around spots exhibits clear periodicity with respect to the TESS light curve. However, the X-ray data does not show such strong association probably because of multiple spots on the surface and the extended spatial structure of coronal active regions (Ikuta et al. 2026). This study enables us to explore the relation between stellar magnetic fields and the stellar atmosphere toward quantifying the stellar XUV radiation to the planetary atmosphere.
Authors 15
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Affiliation as printed
Hitotsubashi University
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Goddard Space Flight Center · Kyoto University · National Aeronautics and Space Administration · Catholic University of America
Affiliation as printed
Kyoto University
National Aeronautics and Space Administration, Goddard Space Flight Center
Catholic University of America
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Affiliation as printed
Université de Toulouse
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Goddard Space Flight Center · American University · National Aeronautics and Space Administration
Affiliation as printed
National Aeronautics and Space Administration, Goddard Space Flight Center
American University
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National Astronomical Observatory of Japan
Affiliation as printed
National Astronomical Observatory of Japan
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University of Colorado Boulder · National Solar Observatory
Affiliation as printed
University of Colorado Boulder
National Solar Observatory
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A. A. Vidotto Aachen
Affiliation as printed
Leiden University
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Goddard Space Flight Center · National Aeronautics and Space Administration
Affiliation as printed
National Aeronautics and Space Administration, Goddard Space Flight Center
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Thüringer Landessternwarte Tautenburg
Affiliation as printed
Thüringer Landessternwarte Tautenburg
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University of Southern Queensland
Affiliation as printed
University of Southern Queensland
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Affiliation as printed
Université de Montpellier
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Affiliation as printed
Sorbonne University
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Nepal Academy of Science and Technology · University of Maryland, College Park
Affiliation as printed
University of Maryland
Nepal Academy of Science and Technology
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Affiliation as printed
Kyoto University
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Doshisha University · Kyoto University
Affiliation as printed
Doshisha University
Kyoto University
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