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The exoplanetary magnetosphere extension in Sun-like stars based on the solar wind -- solar UV relation

Journal
Date Issued
2023
Author(s)
•
•
•
Francesco Berrilli
•
Bertello, Luca
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DEL MORO, DARIO
•
•
Giobbi, Piermarco
•
Valentina Penza
DOI
Abstract
The Earth's magnetosphere extension is controlled by the solar activity level via solar wind properties. Understanding such a relation in the Solar System is important for predicting also the condition of exoplanetary magnetospheres near Sun-like stars. We use measurements of a chromospheric proxy, the Ca II K index, and solar wind OMNI parameters to connect the solar activity variations, on the decennial time scales, to the solar wind properties. The data span over the time interval 1965-2021, which almost entirely covers the last 5 solar cycles. Using both cross-correlation and mutual information analysis, a 3.2-year lag of the solar wind speed with respect to the Ca II K index is found. Analogously, a 3.6-year lag is found once considering the dynamic pressure. A correlation between the solar wind dynamic pressure and the solar UV emission is found and used to derive the Earth's magnetopause standoff distance. Moreover, the advantage of using a chromospheric proxy, such as the Ca II K index, opens the possibility to extend the relation found for the Sun to Sun-like stars, by linking stellar variability to stellar wind properties. The model is applied to a sample of Sun-like stars as a case study, where we assume the presence of an Earth-like exoplanet at 1 AU. Finally, we compare our results with previous estimates of the magnetosphere extension for the same set of Sun-like stars.
Volume
519
Issue
4
Start page
6088
Uri
Url
Issn Identifier
0035-8711
Ads BibCode
2023MNRAS.519.6088R
Rights
open.access
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