One Year in the Life of Young Suns

Author(s): Vladimir Airapetian, Meng Jin, Theresa Lüftinger, Oleg Kochukhov, Manuel Güdel, Bart Van Der Holst, W. Manchester IV
Abstract: The young magnetically active solar-like stars are efficient generators of ionizing radiation in the form of X-ray and extreme-UV (EUV) flux, stellar wind, and eruptive events. These outputs are the critical factors affecting atmospheric escape and chemistry of (exo)planets around active stars. While X-ray fluxes and surface magnetic fields can be derived from observations, the EUV emission, and wind mass fluxes, coronal mass ejections and associated stellar energetic particle events cannot be directly observed. Here, we present the results of a three-dimensional magnetohydrodynamic (MHD) model with inputs constrained by spectropolarimetric data, Hubble Space Telescope/STIS far-UV and X-ray data, and stellar magnetic maps reconstructed at two epochs separated by 11 months. The simulations show that over the course of the year the global stellar corona had undergone a drastic transition from a simple dipole-like to a tilted dipole with multipole field components and thus provided favorable conditions for corotating interaction regions (CIRs) that drive strong shocks. The dynamic pressures exerted by CIRs are 1300 times larger than those observed from the Sun and can contribute to the atmospheric erosion of early Venus, Earth, Mars, and young Earth-like exoplanets. Our data-constrained MHD model provides the framework to model coronal environments of G-M planet-hosting dwarfs. The model outputs can serve as a realistic input for exoplanetary atmospheric models to evaluate the impact of stellar coronal emission, stellar winds, and CIRs on their atmospheric escape and chemistry that can be tested in the upcoming James Webb Space Telescope and ground-based observations.
Organisation(s): Department of Astrophysics
External organisation(s): SETI Institute, Science and Operations Department - Science Division (SCI-SC), University of Michigan, National Aeronautics & Space Administration (NASA), Uppsala University
Journal: The Astrophysical Journal
Volume: 916
No. of pages: 15
ISSN: 0004-637X
DOI: https://doi.org/10.3847/1538-4357/ac081e
Publication date: 08-2021
Peer reviewed: Yes
Austrian Fields of Science 2012: 103003 Astronomy, 103004 Astrophysics
Keywords
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Portal url: https://ucrisportal.univie.ac.at/en/publications/8727ad73-df35-4e55-bc4c-7167eac69c68

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