Journal Article

A search for rapid pulsations in the magnetic cool chemically peculiar star HD 3980*

V. G. Elkin, D. W. Kurtz, L. M. Freyhammer, S. Hubrig and G. Mathys

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 390, issue 3, pages 1250-1257
Published in print November 2008 | ISSN: 0035-8711
Published online October 2008 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2008.13819.x
A search for rapid pulsations in the magnetic cool chemically peculiar star HD 3980*

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The Ap star HD 3980 appears to be a promising roAp candidate based on its fundamental parameters, leading us to search for rapid pulsations with the VLT UV-Visual Echelle Spectrograph (UVES). A precise Hipparcos parallax and estimated temperature of 8100 K place HD 3980 in the middle of the theoretical instability strip for rapidly oscillating Ap stars, about halfway through its main-sequence evolution stage. The star has a strong, variable magnetic field, as is typical of the cool magnetic Ap stars. Dipole model parameters were determined from VLT observations using Focal Reducer and low Dispersion Spectrograph (FORS)1. From Doppler shift measurements for individual spectral lines of rare-earth elements and the Hα line core, we find no pulsations above 20–30 m s−1. This result is corroborated by the inspection of lines of several other chemical elements, as well as with cross-correlation for long spectral regions with the average spectrum as a template. Abundances of chemical elements were determined and show larger than solar abundances of rare-earth elements. Further, ionization disequilibria for the first two ionized states of Nd and Pr are detected. We also find that the star has a strong overabundance of manganese, which is typical for much hotter HgMn and other Bp stars. Line profile variability with the rotation period was detected for the majority of chemical species.

Keywords: stars: individual: HD 3980; stars: magnetic fields; stars: oscillations; stars: variables: other

Journal Article.  5962 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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