Spectrum analysis of the giant Am star HR 178

Spectrographic lines of the Am star HR 178 are discussed in the context of other stars colocated in the evolved zone of the Cepheid instability strip. The 80 pc-distant object has a period over 10 days. The data show that HR 178 is deficient in Ca and Sc and overabundant in Ti, V, Cr, Mn, Fe, Ni, Sr...

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Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 1985-05, Vol.146 (1), p.139-148
Main Authors: VAN'T VEER-MENNERET, C, COUPRY, M. F, BURKHART, C
Format: Article
Language:English
Subjects:
Astronomy
Chemically peculiar stars (ap, am, etc.)
Earth, ocean, space
Exact sciences and technology
Stars
Variable and peculiar stars (including novae)
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Summary:Spectrographic lines of the Am star HR 178 are discussed in the context of other stars colocated in the evolved zone of the Cepheid instability strip. The 80 pc-distant object has a period over 10 days. The data show that HR 178 is deficient in Ca and Sc and overabundant in Ti, V, Cr, Mn, Fe, Ni, Sr, Y and Zr. The Ca and Sc deficiencies are typical of stars on the cool blue side of the Cepheid instability strip, thereby ruling them out, as a class, as delta Scuti objects. The effective surface temperature of HR 178 is estimated to be in the range 7500-8000 K, the surface gravity is in the log g interval 3.0-4.0, and the microturbulent velocity is 6.2 km/sec. Although the metallicity lines are very strong, Fe is only slightly overabundant.
ISSN:0004-6361
1432-0746