Discovery of the longest period rapidly oscillating Ap star HD177765
2012 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 421, no 1, L82-L86 p.Article in journal (Refereed) Published
We present the discovery of a long-period, rapidly oscillating Ap (roAp) star, HD177765. 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 ms(-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 H alpha. We derived the atmospheric parameters and chemical composition of HD177765, showing this star to be similar to other long-period roAp stars. Comparison with theoretical pulsational models indicates an advanced evolutionary state for HD177765. 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.
Place, publisher, year, edition, pages
2012. Vol. 421, no 1, L82-L86 p.
stars: chemically peculiar, stars: individual: HD177765, stars: magnetic field, stars: oscillations
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:uu:diva-174589DOI: 10.1111/j.1745-3933.2011.01211.xISI: 000302693600018OAI: oai:DiVA.org:uu-174589DiVA: diva2:529185