SDSS J160043.6+074802.9: a very rapid sdO pulsator
/ Authors
P. Woudt, D. Kilkenny, E. Zietsman, B. Warner, N. Loaring, C. Copley, A. Kniazev, P. Vaisanen, M. Still, R. Stobie
and 5 more authors
E. Burgh, K. Nordsieck, J. Percival, D. O'donoghue, D. Buckley
/ Abstract
We report the serendipitous discovery of the Sloan Digital Sky Survey (SDSS) star SDSS J160043.6+074802.9 to be a very rapid pulsator. The variation is dominated by a frequency near 8380 μHz (period = 119.33 s) with a large amplitude (0.04 mag) and its first harmonic at 16760 μHz (59.66 s; 0.005 mag). In between these frequencies, we find at least another eight variations with periods between 62 and 118 s and amplitudes between about 0.007 and 0.003 mag; weaker oscillations might also be present. Preliminary spectrograms from the performance verification phase of the Southern African Large Telescope indicate that SDSS J160043.6+074802.9 is a spectroscopic binary consisting of an sdO star and a late-type main-sequence companion. This makes it the first unambiguous detection of such an sdO star to pulsate, and certainly the first found to exhibit multifrequency variations.
Journal: Monthly Notices of the Royal Astronomical Society