New gravitational redshift for the white dwarf omicron/sup 2/ Eri B
Differential measurements of the radial velocities of the DA white dwarf omicron/sup 2/ Eri B and its M4Ve companion, omicron/sup 2/ Eri C, using the coude spectrograph of the 100-in. Mount Wilson telescope, yield a new gravitational redshift of V/sub RS/=+23.9 +- 1.3 (s.d.) km s/sup -1/. 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 +- 0''.006 (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/R/sub sun/=1.30 +- 0.03 is found. Using this, the position of omicron/sup 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/sup 2/ Eri B now seems doubtful.
- Research Organization:
- Department of Astronomy, The Pennsylvania State University, University Park, Pennsylvania 16802
- OSTI ID:
- 5124553
- Journal Information:
- Astron. J.; (United States), Journal Name: Astron. J.; (United States) Vol. 85:9; ISSN ANJOA
- Country of Publication:
- United States
- Language:
- English
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