A spectroscopic analysis of the chemically peculiar star HD207561

TL;DR

This study conducts a detailed spectroscopic analysis of the chemically peculiar star HD207561, revealing it to be an Am star with no detected rapid pulsations, and providing insights into its physical properties and evolutionary status.

Contribution

It provides the first high-resolution spectroscopic and spectro-polarimetric characterization of HD207561, clarifying its nature as an Am star and its position in the delta-Scuti instability strip.

Findings

HD207561 is an Am star with slight under-abundances of Ca and Sc.

The star shows no significant magnetic field within 100 G.

It is a relatively fast rotator with v sin i of 74 km/sec.

Abstract

In this paper we present a high-resolution spectroscopic analysis of the chemically peculiar star HD207561. During a survey programme to search for new roAp stars in the Northern hemisphere, Joshi et al. (2006) 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~6-min]. However, subsequent follow-up observations could not confirm any rapid variability. In order to determine the spectroscopic nature of HD207561, high-resolution spectroscopic and spectro-polarimetric observations were carried out. A reasonable fit of the calculated Hbeta line profile to the observed one yields the effective temperature (Teff) and surface gravity (log g) as 7300 K and 3.7 dex, respectively. The derived projected rotational velocity (vsin i) for HD207561 is 74 km/sec indicative of a relatively fast rotator. The position of HD207561 in the H-R 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 under-abundances of Ca and Sc and mild over-abundances of iron-peak elements. The spectro-polarimetric study of HD207561 shows that the effective magnetic field is within the observational error of 100 gauss (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 HD207561, but low-overtone modes might be excited.