Evolutionary sequence for DA, DB, DC white dwarfs

Journal Article · Sat Sep 01 04:00:00 EDT 1973 · Astron. Astrophys., v. 27, no. 2, pp. 307-315

OSTI ID:4380749

Baglin, A; Vauclair, G

A simple evolutionary scheme is proposed with the hydrogen content as the only parameter. If this content is 0, the white dwarf evolves directly fro DB to DC type through its cooling sequence. If not, the external layer of pure hydrogen, floating at the surface of the star when it is of DA type, becomes con vectively unstable around 15000 deg K. For a critical effective temperature, which is lower when the hydrogen content increases. the whole hydrogen region becomes convective and mixing of the external hydrogen with the inner lelium forces the star to appear as a DB type of a DC type. This process of mixing by convection does not allow a DA type white dwarf to become as hot as the hottest DB types (18000 deg K). So, it is concluded that stars evolve toward the white dwarf stage either with a small amount of hydrogen left or not. (auth)

• Research Organization: Observatory, Nice
• NSA Number: NSA-29-013440
• OSTI ID: 4380749
• Journal Information: Astron. Astrophys., v. 27, no. 2, pp. 307-315, Journal Name: Astron. Astrophys., v. 27, no. 2, pp. 307-315; ISSN AAEJA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

*HYDROGEN-- WHITE DWARF STARS
*WHITE DWARF STARS-- STAR EVOLUTION
CONVECTION
MIXING
N56200* --Physics (Astrophysics & Cosmology)--Stars
TEMPERATURE DEPENDENCE