A spectroscopic analysis of the silicon star HD 34452.
Abstract
Model atmosphere techniques have been used in an analysis of the spectrum of HD 34452. Both the external evidence concerning the mass and radius and the spectroscopic evidence of the hydrogen line profiles and lines of Si rn and Si U indicate that the atmosphere can be described by the basic parameters 0eff= 0.28, log g = 4.2. Helium and neon are found to be deficient while many other elements, including silicon, chlorine, titanium, chromium, iron, strontium, and europium are greatly overabundant. The peculiar composition is compared with theoretical predictions regarding surface reactions due to magnetically accelerated protons and o'-particles; nuclear reactions in the interior followed by mass loss, mixing, or mass-transfer; chemical effects associated with star formation; and diffusive and radiative separation of elements. None of these theories can at present account for the surface composition of HD 34452. Two surprising points are noted. First, it appears that almost all the peculiar stars of types B, A and F, including the metallic line stars, have an excess of iron. Second, the elements of high abundance in HD 34452 could come from silicates and metallic oxides along with such common molecules as H8, H8 0, and HCl, if these constituents formed the last material accreted during star formation onto a star with a stable atmosphere. Key words: silicon star - abundances - model atmospheres
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- December 1970
- Bibcode:
- 1970A&A.....9..380T