A SEARCH FOR SMALL-AMPLITUDE, ACOUSTIC, P-MODE OSCILLATIONS ON ALPHA-CMI

We have searched for small-amplitude, acoustic, p-mode oscillations on the F5 IV-V subgiant alpha CMi (HR 2943) in high-quality Doppler velo city measurements made in 1991, 1992 and 1993 with a magneto-optical-f ilter spectrometer. An internal precision of 0.13 m(2) s(-2) mu Hz(-1) (1 sigma) has been achieved in one of the 1993 data sets. Conclusive evidence for the presence of a p-mode spectrum may be established by e xtracting the mean first-order-half spacing 1/2 Delta nu. Fourier anal ysis of the 1991 and 1992 data appears to indicate the presence of a s trong concentration of periodic power. However, the analysis of substa ntially higher quality 1993 data fails to reveal a strong peak; we are therefore forced to conclude tentatively that we have, at present,fai led to find conclusive evidence for an acoustic oscillation spectrum o n alpha CMi.