Mass Loss Rates for Solar-like Stars Measured from
Lyman alpha Absorption
Brian E. Wood, Hans-Reinhard Mueller, Gary P. Zank, & Jeffrey L. Linsky
Institute: University of Colorado
Institute: University of California at Riverside
Contact Email: woodb@casa.colorado.edu
Abstract:
We present a number of mass loss rate measurements for solar-like stars
with coronal winds, computed using a Ly alpha absorption technique. The
collision between the solar wind and the interstellar wind seen by the Sun
defines the large scale structure of our heliosphere. Similar
structures, ``astrospheres,'' exist around other solar-like stars. The
deceleration of the interstellar wind at the solar or stellar bow shock
heats the interstellar material. Heated neutral hydrogen in the outer
astrosphere (and/or heliosphere) produces a broad Ly alpha absorption
profile that is often detectable in high resolution Hubble Space Telescope
spectra. The amount of absorption is dependent upon the strength of the
stellar wind. With guidance from hydrodynamic models of astrospheres, we
use detected astrospheric Ly alpha absorption to estimate the stellar
mass loss rates. For the solar-like GK stars in our sample, mass loss
appears to increase with stellar activity, suggesting that young, active
stars have stronger winds than old, inactive stars. However, Proxima Cen
(M5.5 Ve) and Lambda And (G8 IV-III + M V) appear to be inconsistent with
this relation.
Index Keywords: Alpha Cen ; Epsilon Eri ; Epsilon Ind ; Lambda And ;
Proxima Cen ; 36 Oph ; 40 Eri A ; 61 Cyg A ; stellar winds ; solar wind
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Manuscript submitted: 2001-Sep-6
"The Future of Cool-Star Astrophysics", 2003, Eds. A. Brown,
G. M. Harper, & T. R. Ayres.
Proceedings of 12th Cambridge Workshop on Cool Stars, Stellar Systems,
& The Sun,
© 2003 University of Colorado.