The p-mode spectrum of γ Equ (HR 8097).

The authors present new high-speed photometric observations of the rapidly oscillating Ap (roAp) star γ Equ acquired on 26 nights during 1992. A frequency analysis of these observations reveals the presence of four p modes with frequencies of 1339, 1366, 1397 and 1427 μHz. These frequencies are all roughly equally spaced by about 30 kHz, which the authors interpret as the spacing of alternating even and odd l modes for a slightly evolved A-type star. This interpretation leads to an asteroseismological luminosity estimate for γ Equ of M_V(Δν) = 1.8, which is in good agreement with the parallax luminosity M_V(π) = 1.9.