On the helium content of the subdwarf binary ADS 16644.
Abstract
Two alternative orbits are determined: an eccentric one with P = 97 years and a circular one with P = 192 years. Both give nearly identical values of the "mass-parameter" W ≡ a3/P2. High-resolution radial velocity data could discriminate between the two orbits and give a direct estimate of masses. With the estimated Mbol= 4.95±0.10 the mass of a single component is M = 1.02±0.26 M_sun;. VandenBerg and Bell (1985) model isochrones for subdwarfs, with α = 1.6, are then used to determine the helium abundance. A rediscussion, using VandenBerg-Bell isochrones, of the location of 9 subdwarfs with reliable trigonometric parallaxes in the Mbol-Te diagram is given.
- Publication:
-
Acta Astronomica
- Pub Date:
- 1987
- Bibcode:
- 1987AcA....37..357S