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摘要
In this paper we present a high-resolution spectroscopic analysis of the chemically peculiar star HD?207561. During a survey programme to search for new rapidly oscillating Ap (roAp) stars in the Northern hemisphere, Joshi et al. observed significant photometric variability on two consecutive nights in the year 2000. The amplitude spectra of the light curves obtained on these two nights showed oscillations with a frequency of 2.79?mHz (P similar to 6?min). However, subsequent follow-up observations could not confirm any rapid variability. In order to determine the spectroscopic nature of HD?207561, high-resolution spectroscopic and spectropolarimetric observations were carried out. A reasonable fit of the calculated H beta line profile to the observed one yields an effective temperature (Teff) and surface gravity (log?g) of 7300?K and 3.7?dex, respectively. The derived projected rotational velocity (v?sin?i) for HD?207561 is 74?km?s-1, indicative of a relatively fast rotator. The position of HD?207561 in the HertzsprungRussell diagram implies that this is slightly evolved from the main-sequence and located well within the delta-Scuti instability strip. The abundance analysis indicates the star has slight underabundances of Ca and Sc and mild overabundances of iron-peak elements. The spectropolarimetric study of HD?207561 shows that the effective magnetic field is within the observational error of 100?G. The spectroscopic analysis revealed that the star has most of the characteristics similar to an Am star, rather than an Ap star, and that it lies in the delta-Scuti instability strip; hence roAp pulsations are not expected in HD?207561, but low-overtone modes might be excited.
- 出版日期2012-8
