Authors: Brian E. Wood (NRL)

Coronal winds are very hard to detect around stars other than the Sun.  One of the only ways to detect such winds is indirectly, through Lyman-alpha absorption from interstellar neutral hydrogen piled up outside the astropauses of nearby Sun-like stars with coronal winds.  This absorption has so far been detected for 22 stars using high resolution UV spectra from the Hubble Space Telescope, and analogous heliospheric absorption has also been detected for many lines of sight from piled-up interstellar hydrogen around our own Sun.  Stronger winds yield larger astrospheres and more Lyman-alpha absorption, so the astrospheric absorption has yielded estimates of mass loss rates for the 22 stars with detected astrospheric absorption, along with upper limits for a number of stars with nondetections.  The astrospheric absorption is sensitive to mass loss over relatively long timescales (months to decades), making it impossible to tell whether the detected wind is quiescent or a product of transients, but the measurements at least provide limits to the amount of mass ejected from active stars by stellar eruptions. One finding is that notorious flare stars do not seem to have tremendously high mass loss rates, suggesting that the frequent strong flares from these stars are NOT necessarily accompanied by massive CMEs. Perhaps many of these strong stellar flares are confined eruptions, as sometimes observed on the Sun.