Chemical Abundances in the A Peculiar Star HD 168733.
1967; Institute of Physics; Volume: 72; Linguagem: Inglês
10.1086/110577
ISSN1538-3881
Autores Tópico(s)Stellar, planetary, and galactic studies
ResumoThe remarkable character of the spectrum of HD 168733 has been noted by Bidelman; we have employed high-dispersion coude spectrograms from Lick Observatory to measure wavelengths, intensities, and secure identifications for lines of 14 elements. An abundance analysis by model atmosphere methods yields the results given in Table I. Mihalas' TABLE I. Number of Log abundance Number of Log abundance Ion lines ED 168733 RSS Ion lines ED 168733 RSS H 12.00 12.00 Cl ii 22 8.310.7 6.25 He 1 2 10.9 11.21 Ti 1 5 9.41(?) 4.58 C ii 5 9.6 10.2 8.60 Ti ii 55 7.210.3 4.58 N ii 13 9.0 10.3 8.05 Cr ii 38 6.510.2 4.90 O I, II none <8.9 8.95 Mn ii none <6.0 4.80 Mgii 3 7.4 10.3 7.40 Fe 1 12 8.210.2 6.59 Si ii 3 7.6510.2 7.50 Fe i~ 20 8.210.2 6.59 Si iii 4 7.9 10.2 7.50 Fe iii 7 9.311.0 6.59 S ii 3 6.8 10.2 7.35 Sr ii 3 6.311.0 2.70 RSS Revised solar system values based on: Goldberg. L., MOiller. E. A., and Aller, L. II. 1960, Astrophys. J. Supp~. 5, 1. MOller, E. A., and Mutschlecner, J. P. 1964, ibid. 9, 1. Aller, L. II. 1961, The Absadeaces of the Etemeats (Interacience Publishers, New York), p. 162. 1965, Advoaces ic Astroaomy aad Astrophysics (Academic Press Inc.. New York), Vol. 3, p. 1. LTE model atmospheres have been employed to compute theoretical line intensities and hydrogen- line profiles. The existing data appear to yield a best fit for an effective temperature of 15 6000K and log g = 3.70. Some of the derived abundances are sensitive to the adopted temperature. Xote that chlorine, titanium, chromium, iron, and particularly strontium are especially abundant. At these temperatures, lines of oxygen and Mn II would not be expected in the observed spectral regions for normal abundances. Magnesium, silicon, and probably helium are normal. A rise in temperature that reduces the abundance of carbon and nitrogen will have the effect of increasing the abundance of iron, titanium, chromium, and strontium.
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