Two new pulsating hot subdwarf stars from the Edinburgh-Cape survey
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Date
2009
Journal Title
Journal ISSN
Volume Title
Publisher
Oxford University Press
Abstract
We report the discovery of very rapid pulsations in two hot subdwarf stars from the Edinburgh-
Cape blue object survey. The short periods, small amplitudes and multiperiodicity establish
these stars as members of the class of rapidly-pulsating sdB stars. The spectrograms of
both stars, however, show relatively strong He II 4686 and they are therefore more properly
classified as sdOB. The light curve of EC 01541?1409 is dominated by two strong
(?1 per cent) variations with frequencies near 7114 and 7870 ?Hz (periods near 140.6 and
127.1 s), though at least five frequencies are present with amplitudes above about 0.002 mag.
The light curve of EC 22221?3152 appears to be generated by at least 10 frequencies in the
range 5670-11850 ?Hz (about 175-85 s) with amplitudes between about 0.01 and 0.001 mag,
including the first overtone of the strongest variation. Somewhat surprisingly, this number of
frequencies is detectable in observing runs as short as 3 h, probably due to the fact that the
detected frequencies are well-separated.
Description
Keywords
Edinburgh-Cape blue object survey, Subdwarfs, Stars: individual: EC 01541?1409, Stars: individual: EC 22221?3152
Citation
Kilkenny, D. et al. (2009). Two new pulsating hot subdwarf stars from the Edinburgh-Cape survey. Monthly Notices of the Royal Astronomical Society, 396(1): 548-552