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G. W. Henry, F. C. Fekel (Tennessee State University)
We use new high-dispersion spectroscopic and precise photometric observations to identify 12 new Gamma Doradus stars. The spectroscopic observations were obtained at Kitt Peak National Observatory. Two of the 12 systems are double-lined binaries. Five other stars show metallic lines that have composite profiles consisting of a narrow component near the center of a broad line. Spectrograms of the H-alpha line indicate that all five stars are binaries rather than shell stars. The other five stars likely have constant radial velocities. Our photometric observations were acquired with the T3 0.40 m automatic photoelectric telescope (APT) at Fairborn Observatory. All 12 stars are photometric variables with amplitudes between 6 and 87 millimagnitudes in Johnson B and periods between about 0.35 and 1.1 days. Four stars are monoperiodic; the rest have between two and five independent periods. All periods are well described as sinusoids. There are now 42 confirmed Gamma Doradus variables. All are dwarfs or sub-giants and lie in a well-defined region of the H-R diagram that overlaps the cool edge of the Delta Scuti instability strip.
This work has been supported by NASA grant NCC5-511 and NSF grant HRD-9706268.
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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.