Document Type

Article

Publication Date

9-2002

Abstract

We present high‐resolution spectroscopy and precision photometry of six new γ Doradus stars, one of which was independently discovered by another group. This brings the total number of confirmed γ Doradus variables to 30. All six of these variables fall in the spectral class range F0–F2; all but one are subgiants. The six stars have between one and five photometric periods in the range 0.3–1.2 days. We find no evidence for higher frequency δ Scuti pulsations in any of these six stars. Our spectroscopic observations reveal HD 108100 to be the first confirmed γ Doradus variable with composite broad and narrow line profiles suggesting the presence of a circumstellar shell or disk. HD 221866 has the most asymmetric absorption lines of the six stars in this paper and also the largest photometric amplitude. Most of the 30 confirmed γ Doradus variables lie in a fairly tight region of the H‐R diagram on or just above the main sequence that partially overlaps the cool edge of the δ Scuti instability strip. However, three stars, including two of the new variables in this paper, are subgiants that lie well within the δ Scuti strip. Among the 30 confirmed γ Doradus variables, we find no correlation between the photometric periods and intrinsic color, absolute magnitude, or luminosity.

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