1995A&A...297..473B

A coordinated photometric campaign of FG Vir at nine observatories covering 170 hours was undertaken by DSN (Delta Scuti Network) and WET (Whole Earth Telescope). Two different observing techniques were adopted for the two telescope networks in order to optimize different frequency ranges. Ten pulsation frequencies between 9.19 and 34.12c/d (112 and 395µHz) were detected with amplitudes ranging from 0.8 to 22mmag. Pulsational instability is observed only in specific frequency regions. Additional frequencies of pulsation within these regions probably exist, but do not reach the significance criterion of amplitude signal/noise adopted by us. Comparisons with previously obtained data show that the amplitudes of the main frequencies are stable over a year or longer. A preliminary identification of the ten dominant frequencies is proposed in a stellar model with 1.8M_☉ in advanced main-sequence phase of evolution. The frequencies correspond to low order p and g modes with l≤2 and radial order 1 to 6. According to the linear nonadiabatic calculations, the identified modes are driven by the opacity mechanism along with many other modes. For asteroseismology of δ Scuti stars, FG Vir is an extremely important candidate, especially because of the probable presence of g modes.