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Record Details

Record 10 of 2490
Origin of the DA and non-DA white dwarf stars
Author and Affiliation:
Shipman, Harry L.(Delaware, University, Newark, United States)
Abstract: Various proposals for the bifurcation of the white dwarf cooling sequence are reviewed. 'Primordial' theories, in which the basic bifurcation of the white dwarf sequence is rooted in events predating the white dwarf stage of stellar evolution, are discussed, along with the competing 'mixing' theories in which processes occurring during the white dwarf stage are responsible for the existence of DA or non-DA stars. A new proposal is suggested, representing a two-channel scenario. In the DA channel, some process reduces the hydrogen layer mass to the value of less than 10 to the -7th. The non-DA channel is similar to that in the primordial scenario. These considerations suggest that some mechanism operates in both channels to reduce the thickness of the outermost layer of the white dwarf. It is also noted that accretion from the interstellar medium has little to do with whether a particular white dwarf becomes a DA or a non-DA star.
Publication Date: Jan 01, 1989
Document ID:
19900045698
(Acquired Nov 28, 1995)
Accession Number: 90A32753
Subject Category: ASTROPHYSICS
Document Type: Conference Paper
Publication Information: (SEE A90-32719)
Publisher Information: Germany
Meeting Information: IAU Colloquium; 114th; Aug. 15-19, 1988; Hanover, NH; United States
Contract/Grant/Task Num: NSF AST-87-20530; NAG5-972; NAG5-348
Financial Sponsor: NASA; United States
Organization Source: Delaware Univ.; Newark, DE, United States
Description: 16p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: PLANETARY NEBULAE; STAR FORMATION; STELLAR EVOLUTION; STELLAR MASS; WHITE DWARF STARS; RED GIANT STARS; STELLAR COMPOSITION; STELLAR ENVELOPES
Imprint And Other Notes: IN: White dwarfs; Proceedings of IAU Colloquium 114th, Hanover, NH, Aug. 15-19, 1988 (A90-32719 13-90). Berlin and New York, Springer-Verlag, 1989, p. 220-235.
Availability Source: Other Sources
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