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On the absence of young white dwarf companions to five technetium starsA search for hot companions to five stars of type MS and S has been carried out using the IUE satellite. No hot companions were detected for the MS stars HR 85, 4647, 6702, and 8062, and the S star HR 8714. Limits on the luminosities of possible white dwarf companions provide lower limits of 2-5x10 to the 8th yr to the ages of any degenerate companions. All five stars exhibit strong Tc I lines, and the presence of technetium, with a half-life of 2.1x10 to the 5th yr, signifies recent nucleosynthesis. The limits on the ages of possible white dwarf companions that are equal to or greater than 1000 half-lives of Tc exclude the possibility that the s-process elemental enhancement seen in these MS and S stars resulted from mass transfer from a more highly evolved companion (as is probably the mechanism by which barium stars are created). These MS and S stars represent a sample of true thermally pulsing asymptotic giant-branch stars.
Document ID
19880026294
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Smith, Verne V. (Texas Univ. Austin, TX, United States)
Lambert, David L. (Texas, University; McDonald Observatory, Austin, United States)
Date Acquired
August 13, 2013
Publication Date
October 1, 1987
Publication Information
Publication: Astronomical Journal
Volume: 94
ISSN: 0004-6256
Subject Category
ASTROPHYSICS
Funding Number(s)
CONTRACT_GRANT: NSG-5379
Distribution Limits
Public
Copyright
Other