Implications of Recent Stellar Wind Measurements

TL;DR

This paper updates stellar wind relations using recent measurements, revealing weak winds in some stars and stronger winds in subgiants, with implications for stellar activity and exoplanet atmospheres.

Contribution

It provides new wind constraints for stars like Tau Ceti and GJ 436, and compares wind strengths across different stellar types and activity levels.

Findings

Tau Ceti has an upper wind limit of Mdot<0.1 Mdot_sun.

Delta Pav exhibits a high mass loss rate of 10 Mdot_sun.

GJ 436 has a very low wind rate of ~0.06 Mdot_sun.

Abstract

Very recent measurements of stellar winds are used to update relations between winds and coronal activity. New wind constraints include an upper limit of Mdot<0.1 Mdot_sun for Tau Ceti (G8 V), derived from a nondetection of astrospheric H I Lyman-alpha absorption. This upper limit is reported here for the first time, and represents the weakest wind constrained using the astrospheric absorption technique. A high mass loss rate measurement of Mdot=10 Mdot_sun for Delta Pav (G8 IV) from astrospheric Lyman-alpha absorption suggests stronger winds for subgiants than for main sequence stars of equivalent activity. A very low mass-loss rate of Mdot~0.06 Mdot_sun recently estimated for GJ 436 (M3 V) from Lyman-alpha absorption from an evaporating exoplanetary atmosphere implies inactive M dwarfs may have weak winds compared with GK dwarfs of similar activity.