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Discovery of very l...
Abstract
Ämnesord
Stäng
- We present our discovery of pulsational radial-velocity variations in the cool Ap star HD75445, an object spectroscopically similar to the bright, rapidly-oscillating Ap (roAp) star gamma Equ. Based on high-resolution time-series spectroscopy obtained with the HARPS spectrometer at the European Southern Observatory 3.6-m telescope, we detected oscillations in Nd II and Nd III lines with a period close to 9 min and amplitudes of 20-30 m s(-1). Substantial variation in the pulsational amplitude during our 3.8 h observing run reveals the presence of at least three excited non-radial modes. The detection of extremely low amplitude pulsations in HD75445 indicates that the roAp excitation mechanism produces variability in the radial velocity amplitude of between a few tens ms(-1) and several km s(-1). This supports the idea that many, if not all, cool Ap stars occupying the roAp instability strip may harbour non-radial pulsations, which currently remain undetected due to their small photometric and radial-velocity amplitudes.
Ämnesord
- NATURVETENSKAP -- Fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences (hsv//eng)
Nyckelord
- stars: atmospheres
- stars: chemically peculiar
- stars: oscillations
- stars: individual: HD75445
- Physics
- Fysik
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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