The EC 14026 stars — XI. Feige 48: a link in its class |
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| Authors: | C Koen D O'Donoghue D L Pollacco & A Nitta |
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| Institution: | South African Astronomical Observatory, PO Box 9, Observatory 7935, Cape, South Africa,;Department of Astronomy, University of Texas at Austin, Austin, TX 78712, USA,;Isaac Newton Group, Santa Cruz de La Palma, Tenerife 38780, Canary Islands, Spain |
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| Abstract: | Rapid oscillations in the sdB star Feige 48 have been discovered. The frequency spectrum reveals at least four periods in a narrow interval from 340 to 380 s. The oscillation amplitude is typically a few per cent, but this star shows perhaps the most dramatic amplitude variability from night to night of any of the known sdB pulsators (EC 14026 stars). Analysis of multicolour absolute photometry, as well as low- and intermediate-dispersion spectroscopy, yields an effective temperature of 28 900 ± 300 K and log g = 5.45 ± 0.05. Feige 48 is thus the coolest EC 14026 star. Its intermediate gravity and intermediate period suggest the existence of a period–gravity correlation, and unite the majority of the EC 14026 stars with the extreme object, PG 1605+072. The narrow frequency intervals in which the pulsations of Feige 48 and other EC 14026 stars fall suggest a narrow bandpass for the excitation mechanism. |
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| Keywords: | stars: individual: Feige 48 stars: oscillations |
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