It is shown that the binary technique - a B star companion is used as a light source which probes the wind of the red giant primary - has yielded accurate mass-loss rates and wind velocities for 8 G to M (super)giants and (in some cases) estimates of wind temperature. Eclipsing binary systems have in addition revealed that G and K supergiants possess extended chromospheres which could be detected outwards to ≡1 R* (stellar radius) above the photospheres. Electron temperatures Te and hydrogen ionization ne/nH4 seem to increase with height up to at least 0.5 R* (ne/nH = 10-2, Te = 104K at 0.5 R*), and the winds start to be accelerated at heights above ≡0.5 R*. Mass-loss rates appear to increase steeper than linearly with L/gR. It is shown that the observed mass-loss rates are consistent with stellar evolution constraints for both Pop II and Pop I stars.
- Pub Date:
- Binaries:Mass Loss;
- Late-Type Stars:Mass Loss;
- Mass Loss:Binaries;
- Mass Loss:Late-Type Stars;
- Stellar Chromospheres:Supergiants;
- Supergiants:Stellar Chromospheres