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SDSS J160043.6+074802.9: a very rapid sdO pulsator |
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| Authors: | P A Woudt D Kilkenny E Zietsman B Warner N S Loaring C Copley A Kniazev P Väisänen M Still R S Stobie E B Burgh K H Nordsieck J W Percival D O'Donoghue D A H Buckley |
| Institution: | Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa;South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa;National Astrophysics and Space Science Programme, University of Cape Town, Rondebosch 7700, South Africa;Space Astronomy Laboratory, University of Wisconsin, Madison, WI 53706, USA |
| 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. |
| Keywords: | stars: individual: SDSS J160043 6+074802 9 stars: oscillations stars: variables: other |