The OB subdwarf Feige 66, a chemical-composition twin to HD 149382.

Abstract

The ultraviolet (1160 to 3230 A) and the blue spectrum of the OB subdwarf, Feige 66, is analyzed differentially to HD 149382. The effective temperature, the surface gravity and the helium abundance of Feige 66 deviate only very little from those of HD 149382. The line spectra are almost identical, and the same strange abundance pattern as in HD 149382 is found in Feige 66. In particular, silicon is extremely deficient relative to a solar mixture. A sulfur enrichment in Feige 66 is the only significant heavy element abundance difference between the two stars.