Using Astrospheric Lyα Absorption Observed by HST to Study the Stellar Winds of α Cen AB and Proxima Cen
Abstract
Using HST observations of the nearby α Cen AB binary system (G2 V+K0 V) and its distant companion star Proxima Cen (M5.5 Ve), we study H I Lyα absorption produced by heated neutral hydrogen gas in the heliosphere, and we also study absorption from analogous ``astrospheric'' material surrounding the stars. We use these data to show how astrospheric Lyα absorption allows us for the first time to estimate the properties of solar-like stellar winds. Unlike α Cen AB, no astrospheric absorption whatsoever is detected toward Proxima Cen, suggesting that Proxima Cen's wind must be significantly weaker than that of the α Cen AB system. Hydrodynamic models of the astrospheres are computed assuming different mass-loss rates to determine which predict the correct amount of H I absorption, and these studies suggest a mass-loss rate of ˙ {M} ≈ 2 ˙ {M}sun for α Cen AB and ˙ {M} <= 0.2 ˙ {M}sun for Proxima Cen. Support for this work is provided by NASA grants NAG5-9041 and S-56500-D to the University of Colorado.
- Publication:
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American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2000
- Bibcode:
- 2000AAS...197.0804W