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Session 59 - Pulsating/Variable Stars.
Display session, Wednesday, June 12
Procyon (\alpha CMi F5 IV) has long been a promising candidate for detection of solar-like p-modes. Although several authors have reported evidence for low-amplitude (\leq 10) m/s pulsations in this star, none of the existing observations are conclusive. A clear detection of such pulsations would be a significant step for asteroseismology of Sun-like stars, allowing refined estimates of the star's properties and paving the way for the study of fainter stars of similar spectral type. Identification of oscillation modes in subgiants like Procyon is expected to be difficult, however, because both the amplitudes and the frequency separations of the modes are expected to be small. To address these difficulties, we organized a joint observing campaign involving the AFOE spectrograph located at the Whipple Observatory (Mt. Hopkins, AZ) and the MUSICOS spectrograph located at Pic du Midi. Both instruments are capable of providing Doppler measurements with the required precision of a few m/s, and the 7 hour longitude separation between them allows the acquisition of relatively long uninterrupted data strings. In the event, bad weather prevented more than sporadic observations from Pic du Midi. At Mt. Hopkins, however, we obtained good observations on each of 6 consecutive nights 3-8 Feb 1996, for a total of 47 h of observing time. We discuss here the interpretation of this data set in terms of possible p-mode oscillations.
Program listing for Wednesday