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Neutron stars and white dwarfs in galactic halos?The possibility that galactic halos are composed of stellar remnants such as neutron stars and white dwarfs is discussed. On the basis of a simple model for the evolution of galactic halos, researchers follow the history of halo matter, luminosity, and metal and helium abundances. They assume conventional yields for helium and the heavier elements. By comparing with the observational constraints, which may be considered as fairly conservative, it is found that, for an exponentially decreasing star formation rate (SFR) with e-folding time tau, only values between 6 x 10(8) less than similar to tau less than similar to 2 x 10(9) years are allowed together with a very limited range of masses for the initial mass function (IMF). Star formation is allowed for 2 solar mass less than similar to m less than similar to 8 solar mass if tau = 2 x 10(9) years, and for 4 solar mass less than similar to m less than similar to 6 solar mass if tau = 10(9) years. For tau = 6 x 10(8) years, the lower and upper mass limits merge to similar to 5 solar mass. Researchers conclude that, even though the possibility of neutron stars as halo matter may be ruled out, that of white dwarfs may still be a viable hypothesis, though with very stringent constraints on allowed parameters, that merits further consideration.
Document ID
19900043854
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Ryu, Dongsu
(NASAFermilab Astrophysics Center Batavia, IL, United States)
Olive, Keith A.
(Minnesota, University Minneapolis, United States)
Silk, Joseph
(California, University Berkeley, United States)
Date Acquired
August 14, 2013
Publication Date
April 10, 1990
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 353
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
90A30909
Funding Number(s)
CONTRACT_GRANT: NAGW-1340
CONTRACT_GRANT: DE-AC02-83ER-40105
Distribution Limits
Public
Copyright
Other

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