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A spectroscopic study of southern (candidate) gamma Doradus stars. I. Time series analysis

P. De Cat·L. Eyer·J. Cuypers·C. Aerts·B. Vandenbussche·K. Uytterhoeven·K. Reyniers·K. Kolenberg·M. Groenewegen·G. Raskin·T. Maas·S. Jankov
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Abstract

We present results of a spectroscopic study of 37 southern (candidate) gamma Doradus stars based on echelle spectra. The observed spectra were cross-correlated with the standard template spectrum of an F0-type star for an easier detection of binary and intrinsic variations. We identified 15 objects as spectroscopic binaries, including 7 new ones, and another 3 objects are binary suspects. At least 12 objects show composite spectra. We could determine the orbital parameters for 9 binaries, of which 4 turn out to be ellipsoidal variables. For 6 binaries, we estimated the expected time-base of the orbital variations. Clear profile variations are observed for 17 objects, pointing towards stellar pulsation. For 8 of them, we have evidence that the main spectroscopic and photometric periods coincide. Our results, in combination with prior knowledge from the literature, lead to the classification of 10 objects as new bona-fide gamma Doradus stars, 1 object as new bona-fide delta Scuti star, and 8 objects as constant stars. Finally, we determined the projected rotational velocity with two independent methods. The resulting vsini values range from 3 to 135 km/s. For the bona-fide gamma Doradus stars, the majority has vsini below 60 km/s.

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P. De Cat, L. Eyer, J. Cuypers, C. Aerts, B. Vandenbussche, K. Uytterhoeven, K. Reyniers, K. Kolenberg, M. Groenewegen, G. Raskin, T. Maas, S. Jankov. 2005-11-08. A spectroscopic study of southern (candidate) gamma Doradus stars. I. Time series analysis. https://doi.org/10.1051/0004-6361%3A20053655

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