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Title:
Discovery of the longest period rapidly oscillating Ap star HD 177765
Authors:
Alentiev, D.; Kochukhov, O.; Ryabchikova, T.; Cunha, M.; Tsymbal, V.; Weiss, W.
Affiliation:
AA(Department of Physics, Tavrian National University, Vernadskiy's Avenue 4, 95007 Simferopol, Ukraine; Centro de Astrofisica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal), AB(Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden), AC(Institute of Astronomy, Russian Academy of Sciences, Pyatnitskaya 48, 119017 Moscow, Russia), AD(Centro de Astrofisica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal), AE(Department of Physics, Tavrian National University, Vernadskiy's Avenue 4, 95007 Simferopol, Ukraine), AF(Department of Astronomy, University of Vienna, Türkenschanzstrasse 17, 1180 Wien, Austria)
Publication:
Monthly Notices of the Royal Astronomical Society: Letters, Volume 421, Issue 1, pp. L82-L86. (MNRAS Homepage)
Publication Date:
03/2012
Origin:
WILEY
Astronomy Keywords:
stars: chemically peculiar, stars: individual: HD 177765, stars: magnetic field, stars: oscillations
Abstract Copyright:
© 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS
DOI:
10.1111/j.1745-3933.2011.01211.x
Bibliographic Code:
2012MNRAS.421L..82A

Abstract

We present the discovery of a long-period, rapidly oscillating Ap (roAp) star, HD 177765. Using high-resolution time-series observations obtained with the Ultraviolet and Visual Echelle Spectrograph at the European Southern Observatory Very Large Telescope, we found radial velocity variations with amplitudes 7-150 m s-1 and a period of 23.6 min, exceeding that of any previously known roAp star. The largest pulsation amplitudes are observed for Eu III, Ce III and for the narrow core of Halpha. We derived the atmospheric parameters and chemical composition of HD 177765, showing this star to be similar to other long-period roAp stars. Comparison with theoretical pulsational models indicates an advanced evolutionary state for HD 177765. Abundance analyses of this and other roAp stars suggest a systematic variation with age of the rare-earth line anomalies seen in cool Ap stars. <title type="main">Footnotes<label>1</label>
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