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Record Details

Record 63 of 8813
Does the upper main sequence extend across the whole H-R diagram. [radiative opacities of stellar evolution models]
External Online Source: doi:10.1086/154919
Author and Affiliation:
Stothers, R.(NASA Goddard Inst. for Space Studies, New York, NY, United States)
Chin, C.-W.(NASA Goddard Institute for Space Studies, New York, N.Y., United States)
Abstract: The effect of using Carson's (1976) radiative opacities in evolutionary sequences of stellar models has been studied over the mass range from 7 to 60 solar masses. The opacities are very large in the outer part of the envelope and induce such enormous radii for masses greater than about 30 solar masses for a heavy-element fraction of 0.02 or about 20 solar masses for a heavy-element fraction of 0.04 that the evolutionary tracks during the phase of core hydrogen burning extend across the whole H-R diagram. The choice of the Schwarschild or Ledoux criterion for convection makes very little difference for the behavior of the tracks. Evolution through the effective-temperature range (in logarithms) of 3.6 to 4.0 occurs in all cases on a rapid (secular) time scale. Core helium burning takes place exclusively in the red-supergiant configuration for stellar masses exceeding 8 solar masses (heavy-element fraction of 0.02) or 6 solar masses (heavy-element fraction of 0.04). These stellar models seem to be in significantly better agreement with the observed distribution of bright stars on the H-R diagram than are the older models based on the Cox-Stewart opacities. It can be inferred that a large envelope opacity (e.g., Carson's) exists and that substantial mass loss takes place in very massive late-type supergiants.
Publication Date: Jan 01, 1977
Document ID:
19770034820
(Acquired Dec 01, 1995)
Accession Number: 77A17672
Subject Category: ASTROPHYSICS
Document Type: Journal Article
Publication Information: Astrophysical Journal; p. Jan. 1; 211
Publisher Information: United States
Financial Sponsor: NASA; United States
Organization Source: NASA Goddard Inst. for Space Studies; New York, NY, United States
Description: 9p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: HERTZSPRUNG-RUSSELL DIAGRAM; MAIN SEQUENCE STARS; OPACITY; RADIATIVE TRANSFER; STELLAR EVOLUTION; STELLAR MODELS; HYDROGEN ATOMS; NUCLEAR REACTIONS; REACTION KINETICS; STELLAR ENVELOPES; STELLAR LUMINOSITY; STELLAR MASS EJECTION; STELLAR TEMPERATURE; SUPERGIANT STARS
Imprint And Other Notes: Astrophysical Journal, vol. 211, Jan. 1, 1977, pt. 1, p. 189-197.
Miscellaneous Notes: 1977, pt. 1, p. 189-197
Availability Source: Other Sources
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