Dursun Kocer

Elemental abundance analyses with DAO spectrograms - XXV. The superficially normal B and A stars

Elemental abundances analyses of the superfically normal B and A stars α Dra (A0 III), τ Her (B5 IV), γ Lyr (B9 III), and HR 7926 (B8 II-III) are performed consistent with previous studies of this series using spectrograms obtained with Reticon and CCD detectors. Comparisons of the first two analyses with those of the same stars performed earlier in this series which used mostly coadded photographic plates show the general consistency of the derived elemental abundances. A slight increase in the adopted effective temperature produces a corresponding increase in the derived abundances. In these stars the He/H ratios are found to be close to solar. Except for γ Lyr the metals show for the most part marginally subsolar abundance values. But this star has Al, Ca, Sc, and Sr abundances that are substantially underabundant as well as other underabundant values.

\alpha

The superficially normal stars And (A2 V), Del (B6 III), Aqr (A1.5 V), and And (B9 V), which have ro- tationally broadened line profiles, are analyzed in a manner consistent with previous studies of this series using 2.4 A mm 1 spectrograms obtained with CCD detectors and S=N 200. Their variable radial velocities strongly suggest they are spectro- scopic binaries. As no evidence is seen for lines of their companions they are analyzed as single stars. Their derived abundances are generally near solar. But those for And suggest that it is possibly a fast rotating Am star.

Draconis,

Elemental abundances analyses of the superfically normal stars γ Ser (F6 V) and 101 Herculis (A7 V) consistent with previous studies of this series using photographic region spectrograms obtained with Reticon and CCD detectors produced derived values that are generally solar except for Al which is very underabundant and the rare earths which do not have the solar pattern. Similar discrepancies from solar values are seen in other superficially normal stars of this series with similar temperatures. Our results for γ Ser are in acceptable agreement with other recent studies based on different techniques and spectral regions.

\tau

Two fine analyses of the A0 III star Alpha Dra were performed using the same sources of atomic data, the same spectrophotometric data, and the same model-atmospheres code, but with photographic region spectrograms obtained at two different observatories, Kitt Peak National Observatory and Dominion Astrophysical Observatory. The resultant values show differences typically of the order of a factor of two with the higher signal-to-noise data yielding smaller abundances. On the whole, Alpha Dra is a star with abundances typically one-third solar; however, it is definitely scandium and nickel poor. Its abundance pattern shows a strong resemblance to those of Vega and other metal-poor A stars.

Herculis,

We are performing elemental abundances of sharp-lined metallic-lined stars and normal late A through middle F stars using 2.4 A mm −1 photographic region spectrograms taken with the coude spectrograph of the 1.4-m telescope of the Dominion Astrophysical Observatory. Our initial studies of the Am stars 15 Vul and 32 Aqr and the normal stars θ Cyg (F4 V) and ɩ Psc (F7 V) showed that the elemental abundances of the normal stars were close to solar while 15 Vul shows smaller abundance anomalies than does 32 Aqr. These analyses are being done consistently with SJA’s studies of the HgMn and hotter normal stars.

\gamma

Prelimary results from an optical region study of the metallic-lined star 32 Aquarii indicate Teff = 7600 K, log g = 3.10, ξ = 4.6 km s-1, and an iron abundance about one-half solar.