O. Kochukhov, D. Alentiev, T. Ryabchikova, S. Boyko, M. S. Cunha, V. Tsymbal, W. W. Weiss
We have carried out a survey of short-period pulsations among a sample of carefully chosen cool Ap stars using time-resolved observations with the Ultraviolet and Visual Echelle Spectrograph at the European Southern Observatory ESO 8 m Very Large Telescope. Here, we report the discovery of pulsations with amplitudes 50–100 m s-1 and periods 7–12 min in HD 132205, HD 148593 and HD 151860. These objects are therefore established as new rapidly oscillating Ap (roAp) stars. In addition, we independently confirm the presence of pulsations in HD 69013, HD 96237 and HD 143487 and detect, for the first time, radial velocity oscillations in two previously known photometric roAp stars HD 119027 and HD 185256. At the same time, no pulsation variability is found for HD 5823, HD 178892 and HD 185204. All of the newly discovered roAp stars were previously classified as non-pulsating based on the low-precision ground-based photometric surveys. This shows that such observations cannot be used to reliably distinguish between pulsating and non-pulsating stars and that all cool Ap stars may harbour p-mode pulsations of different amplitudes.
techniques: spectroscopic - stars: chemically peculiar - stars: magnetic field - stars: oscillations - stars: variables: general
Based on observations collected at the European Southern Observatory, Paranal, Chile (program 085.D-0124).
Monthly Notices of the Royal Astronomical Society
Volume 431, Issue 3, Page 2808