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The evolution of hydrogen-helium stars.Investigation of the premain sequence evolution and the main sequence evolution of stars of 5, 10, 20, 30, 100, and 200 solar masses. Normal stars in this entire mass range normally convert hydrogen into helium by the CN-cycle on the main sequence. The present hydrogen-helium stars of 5 and 10 solar masses must reach higher central temperatures in order to convert hydrogen to helium by the proton-proton chains. Consequently, the mean densities in the stars are greater, and the surface temperatures are higher than in normal stars. In the stars of 20 solar masses and larger, the proton-proton chains do not succeed in supplying the necessary luminosity of the stars by the time the contraction has produced a central temperature near 10 to the 8th K. At that point triple-alpha reactions generate small amounts of C12, which then acts as a catalyst in the CN-cycle, the rate of which is then limited by the beta-decays occurring within the cycle. During the evolution of these more massive stars, the central temperature remains in the vicinity of 10 to the 8th K, and the surface temperature on the main sequence approaches 100,000.
Document ID
19720035915
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Ezer, D.
(NASA Goddard Institute for Space Studies New York, N.Y., United States)
Cameron, A. G. W.
(Yeshiva University; NASA, Goddard Institute for Space Studies, New York, N.Y., United States)
Date Acquired
August 6, 2013
Publication Date
December 1, 1971
Publication Information
Publication: Astrophysics and Space Science
Volume: 14
Subject Category
Space Sciences
Accession Number
72A19581
Distribution Limits
Public
Copyright
Other

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