A new gravitational redshift for the white dwarf omi2 ERI B.
Abstract
Differential measurements of the radial velocities of the DA white dwarf Omicron(2) Eri B and its M4V3 companion, Omicron(2) Eri C, using the coude spectrograph of the 100-in. Mount Wilson telescope, yield a new gravitational redshift of V(RS) = +23.9 + or - 1.3 (s.d.) km/s. Corrections for the binary's orbital motion, the small gravitational redshift of the nondegenerate companion, and atmospheric refraction have been included in the reduction. At the present level of accuracy, the redshift, mass, and radius are inconsistent, but reconsideration of the errors and a slight lowering of the parallax to pi = +0.204 + or - 0.006 arcsec (s.d.) partially removes this problem. The radius is more insensitive to the parallax than the mass in the redshift-radius diagram. After a re-discussion of the radius, a value of 100R/solar radius = 1.30 + or - 0.03 is found. Using this, the position of Omicron(2) Eri B seems to agree with the Hamada and Salpeter mass-radius relations and stellar evolutionary theory, which predicts a carbon-oxygen core. The possibility of an iron core for Omicron(2) Eri B now seems doubtful.
- Publication:
-
The Astronomical Journal
- Pub Date:
- September 1980
- DOI:
- 10.1086/112792
- Bibcode:
- 1980AJ.....85.1255W
- Keywords:
-
- Radial Velocity;
- Red Shift;
- Stellar Gravitation;
- Stellar Rotation;
- Stellar Spectra;
- White Dwarf Stars;
- Astrometry;
- Emission Spectra;
- H Alpha Line;
- Radii;
- Stellar Mass;
- Astrophysics