Modelling the chromosphere and transition region of Epsilon Eri (K2 V)

Abstract

Measurements of ultraviolet line fluxes from Space Telescope Imaging Spectrograph and Far-Ultraviolet Spectroscopic Explorer spectra of the K2-dwarf Epsilon Eri are reported. These are used to develop new emission measure distributions and semi-empirical atmospheric models for the chromosphere and lower transition region of the star. These models are the most detailed constructed to date for a main-sequence star other than the Sun. New ionisation balance calculations, which account for the effect of finite density on dielectronic recombination rates, are presented for carbon, nitrogen, oxygen and silicon. The results of these calculations are significantly different from the standard Arnaud & Rothenflug ion balance, particularly for alkali-like ions. The new atmospheric models are used to place constraints on possible First Ionisation Potential (FIP) related abundance variations in the lower atmosphere and to discuss limitations of single-component models for the interpretation of certain optically thick line fluxes.

arXiv comment22 pages, 9 figures

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Cited by in corpus (10)

• The FIP and Inverse FIP Effects in Solar and Stellar Coronae
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• HAZMAT VI: The Evolution of Extreme Ultraviolet Radiation Emitted from Early M Star
• From Radio to X-ray: The Quiescent Atmosphere of the dMe Flare Star EV Lacertae
• Predicting the Extreme Ultraviolet Radiation Environment of Exoplanets Around Low-Mass Stars: GJ 832, GJ 176, GJ 436
• Coronal Emission Measures and Abundances for Moderately Active K Dwarfs Observed by Chandra
• The corona and upper transition region of epsilon Eridani
• Chromospheric changes in K stars with activity
• Accurate Modeling of Lyman-alpha Profiles and their Impact on Photolysis of Terrestrial Planet Atmospheres
• CHIANTI -- an atomic database for emission lines -- Paper XVIII. Version 11, advanced ionization equilibrium models: density and charge transfer effects