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Estimating stellar wind parameters from low-resolution magnetograms

Authors :
Victor See
Aline A. Vidotto
Moira Jardine
Science & Technology Facilities Council
University of St Andrews. School of Physics and Astronomy
Source :
Monthly Notices of the Royal Astronomical Society: Letters. 465:L25-L29
Publication Year :
2016
Publisher :
Oxford University Press (OUP), 2016.

Abstract

Stellar winds govern the angular momentum evolution of solar-like stars throughout their main-sequence lifetime. The efficiency of this process depends on the geometry of the star's magnetic field. There has been a rapid increase recently in the number of stars for which this geometry can be determined through spectropolarimetry. We present a computationally efficient method to determine the 3D geometry of the stellar wind and to estimate the mass loss rate and angular momentum loss rate based on these observations. Using solar magnetograms as examples, we quantify the extent to which the values obtained are affected by the limited spatial resolution of stellar observations. We find that for a typical stellar surface resolution of 20$^{\rm o}$-30$^{\rm o}$, predicted wind speeds are within 5$\%$ of the value at full resolution. Mass loss rates and angular momentum loss rates are within 5-20$\%$. In contrast, the predicted X-ray emission measures can be under-estimated by 1-2 orders of magnitude, and their rotational modulations by 10-20$\%$.<br />Comment: 6 pages, 6 figures

Details

ISSN :
17453933 and 17453925
Volume :
465
Database :
OpenAIRE
Journal :
Monthly Notices of the Royal Astronomical Society: Letters
Accession number :
edsair.doi.dedup.....c9ac4b547c5da7aa257b0cef565b3f2c