The domain of γ Doradus variables in the Hertzsprung–Russell diagram |
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Authors: | G Handler |
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Institution: | South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa |
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Abstract: | 70 new γ Doradus candidates were identified from Hipparcos photometry, which represents more than a doubling of the presently known number. Selecting the objects with good evidence for multiperiodicity, it is found that these stars, together with bona fide members of the class, occupy a well-defined region in a colour–magnitude diagram. This domain corresponds to a range of 7200–7700 K on the zero-age main sequence (ZAMS) and 6900–7500 K one magnitude above it, which partly overlaps with the instability strip of δ Scuti stars. For the first time, γ Doradus stars can be discussed as a group. They can be found over a significant fraction of the main sequence lifetimes for objects in the relevant temperature range. An upper limit on the surface metallicity of γ Doradus stars is apparent, which may guide the search for their pulsation driving mechanism. The importance of possible objects exhibiting both γ Doradus and δ Scuti-type pulsations is discussed. |
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Keywords: | Hertzsprung–Russell (HR) diagram stars: oscillations δ Scuti stars: variables: other |
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