Estimating stellar wind parameters from low-resolution magnetograms

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${}^{\mathrm{o}}$-30${}^{\mathrm{o}}$, 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$\%$.

6 pages, 6 figures

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Cited by in corpus (5)

• The evolution of surface magnetic fields in young solar-type stars II: The early main sequence (250-650 Myr)
• Estimating magnetic filling factors from Zeeman-Doppler magnetograms
• Do non-dipolar magnetic fields contribute to spin-down torques?
• The open flux evolution of a solar-mass star on the main sequence
• The circumstellar environment of 55 Cnc: The super-Earth 55 Cnc e as a primary target for star-planet interactions