Line profile variations in Doradus

We present data from high-dispersion echelle spectra and simultaneous $uvby$photometry for $\gamma$~Doradus. These data were obtained from several sitesduring 1994 November as part of the MUSICOS-94 campaign. The star has twoclosely-spaced periods of about 0.75 d and is the brightest member of a newclass of variable early F-type stars. A previously suspected third period, veryclose to the other two, is confirmed. Previous observations indicated thatsudden changes could be expected in the spectrum, but none were found duringthe campaign. The radial velocities rule out the possibility of a closecompanion. The phasing between the radial velocity and light curve of thestrongest periodic component rules out the starspot model. The only viablemechanism for understanding the variability is nonradial pulsation. We used themethod of moments to identify the modes of pulsation of the three periodiccomponents. These appear to be sectorial retrograde modes with sphericalharmonic degrees, ($\ell, m$), as follows: $f_1$ = (3,3), $f_2$ = (1,1) and$f_4$ = (1,1). The angle of inclination of the star is found to be $i \approx70^\circ$.Comment: 11 pages, 10 figures, accepted to Monthly Notices of the Royal Astronomical Societ