On the spectroscopic nature of the cool evolved Am star HD151878
arXiv:0807.2821 · doi:10.1111/j.1365-2966.2008.13726.x
Abstract
Recently, Tiwari, Chaubey, & Pandey (2007) detected the bright component of the visual binary HD151878 to exhibit rapid photometric oscillations through a Johnson B filter with a period of 6 min (2.78 mHz) and a high, modulated amplitude up to 22 mmag peak-to-peak, making this star by far the highest amplitude roAp star known. As a new roAp star, HD151878 is of additional particular interest as a scarce example of the class in the northern sky, and only the second known case of an evolved roAp star - the other being HD 116114. We used the FIES spectrograph at the Nordic Optical Telescope to obtain high time resolution spectra at high dispersion to attempt to verify the rapid oscillations. We show here that the star at this epoch is spectroscopically stable to rapid oscillations of no more than a few tens of m/s. The high-resolution spectra furthermore show the star to be of type Am rather than Ap and we show the star lacks most of the known characteristics for rapidly oscillating Ap stars. We conclude that this is an Am star that does not pulsate with a 6-min period. The original discovery of pulsation is likely to be an instrumental artefact.
arXiv commentAccepted for publication in the Monthly Notices of the Royal Astronomical Society Main Journal
References in corpus (10)
- Validation of the new Hipparcos reduction
- The Core-Wing Anomaly of Cool Ap Stars: Abnormal Balmer Profiles
- Discovery of 17 new sharp-lined Ap stars with magnetically resolved lines
- Radial Velocity Variations in Pulsating Ap Stars III. The Discovery of 16.21 min Oscillations in Beta CrB
- The Nainital-Cape Survey-III : A Search for Pulsational Variability in Chemically Peculiar Stars
- Discovery of unusual pulsations in the cool, evolved Am stars HD 98851 and HD 102480
- Discovery of pulsational line profile variations in the delta Scuti star HD21190 and in the Ap Sr star HD218994
- The rapidly oscillating Ap star HD 99563 and its distorted dipole pulsation mode
- A search for rapid pulsations among 9 luminous Ap stars
- Lithium in field Am and normal A-F-type stars