MEASURING STELLAR OSCILLATIONS USING EQUIVALENT WIDTHS OF ABSORPTION-LINES

Kjeldsen et al. have developed a new technique for measuring stellar o scillations, and claimed a detection in the G subgiant eta Boo. The te chnique involves monitoring temperature fluctuations in a star via the ir effect on the equivalent width of Balmer lines. In this paper we us e synthetic stellar spectra to investigate the temperature dependence of the Balmer lines, Ca II, Fe I, the Mg b feature and the G band. We present a list of target stars likely to show solar-like oscillations, and estimate their expected amplitudes. We also show that centre-to-l imb variations in Balmer-line profiles allow one to detect oscillation modes with l less than or equal to 4, which accounts for the detectio n by Kjeldsen et al. of modes with degree l=3 in integrated sunlight.