Photometry and spectroscopy of 11 γ Doradus stars

We have used precise photometric and high-dispersion spectroscopic observations to study 11 gamma Doradus stars, 10 of them newly confirmed. Only five of these 11 gamma Doradus stars appear to be single; two are primaries of double-lined spectroscopic binaries, one is the secondary of a double-lined binary, two are primaries of visual binaries and, in the case of the double-lined binary (HD 86371), either or both components could be a pulsating gamma Doradus star. We have determined a preliminary orbital period of 5.32 days for the double-lined binary HD 41547. Several of the stars show spectroscopic line-profile and low-amplitude radial velocity variability indicative of pulsation. All 11 stars are photometrically variable with amplitudes between 4 and 94 mmag in Johnson B and periods between 0.38 and 1.86 days. The 11 stars have between two and five independent periods. The variability at all periods approximates a sinusoid. We provide a new tabulation of all 66 gamma Doradus stars confirmed to date and list some of their properties. All are dwarfs or subgiants and lie within a well-defined region of the H-R diagram that overlaps the cool edge of the delta Scuti instability strip. Four of the new gamma Doradus variables from this paper also lie within the delta Scuti instability strip but do not exhibit the additional higher frequency variability typical of delta Scuti stars. Among the 66 confirmed gamma Doradus variables, we find no correlation between the period of the strongest pulsation mode and the (B-V) color index, absolute magnitude, or luminosity.