A SEARCH FOR SOLAR-LIKE OSCILLATIONS IN ALPHA-CENTAURI-A

We describe spectrographic observations made in the course of a search for solar-like acoustic oscillations in α Cen A. The observational method was to search for periodical Doppler-shift variations in all of the spectrum lines within the wavelength range accessible to a high-dispersion echelle spectrograph - about 30 nm centered on 427.5 nm, in our case. We also searched for variations in the ratio of line core to continuum intensity, again averaged over all the available lines. We found no convincing oscillations in either case, with upper limits for typical single oscillation mode of 70 cm s-1 in Doppler shift and 4 × 10-5 for continuum intensity variations inferred from line core intensities.