1996A&A...312..855M

Simultaneous photometric B, V (14 consecutive nights; 100 hours of observations) and high resolution spectroscopic observations (4 consecutive nights; 27 hours) were performed on the δ Scuti star X Caeli at La Silla Observatory in 1992. The photometric data allow the detection of 14 pulsation terms, some of which coincide in frequency with the second harmonics or the non-linear coupling terms of the lower frequency components. Possible excitation by resonance is suggested. The comparison with our previous observations of 1989 shows that while the amplitude of the strongest term (ν=7.39c/d) is very stable, a few other terms have changed their amplitudes. From the study of line profiles and their variations we derive vsin i=70km/s, 65deg≤i≤90deg, and that the dominant photometric term is a prograde mode with m=-1 and l=1 or 2. The other terms are probably non radial p modes with l=2±1. There is no evidence of the presence of high-degree sectorial modes with l=|m|. The stellar spectral lines have a narrow absorption core which could be due to the presence of a circumstellar shell.