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| Paper: |
The Effects of Metallicity on Delta Scuti Star Asteroseismology |
| Volume: |
135, A Half Century of Stellar Pulsation Interpretations: a Tribute to Arthur N. Cox |
| Page: |
470 |
| Authors: |
Guzik, J. A.; Templeton, M. R.; Bradley, P. A. |
| Abstract: |
In delta Scuti asteroseismology, most reseachers use evolution and pulsation models assuming a solar element mixture and metal abundance Z=0.02. Here, we quantify the validity of this assumption by investigating the effect of metallicity on the mode identifications and our mass and evolutionary state determinations of delta Scuti and FG Virginis. Both stars have a number of well-determined frequencies (6 for delta Scuti and 22 for FG Vir), making them suitable candidates for asteroseismology. These stars have large reported [Fe/H] values, although spectroscopically-derived abundances show substantial over- and under-abundances of individual elements compared to the solar case. Previously, we suggested mode identifications for the observed frequencies using Z=0.02 stellar models (see refs. below). We found that even a small change in metallicity (from 0.02 to 0.0183) affects the convective core size, and shifts the frequencies of g-type modes that are sensitive to the core structure by several microhertz. We repeat our analysis using Z=0.03 models that may be appropriate for FG Vir, and Z=0.06 models for delta Scuti. We would like to determine whether these higher-Z models give a more plausible fit to the observed frequencies, and how much metallicity affects our asteroseismological inference of the mass and evolutionary state. References: Guzik, J. A. and Bradley, P. A., Baltic Astronomy 4, 422 (1995), Templeton, M. A., McNamara, B.J., Guzik, J.A., Bradley, P. A., Cox, A. N., and Middleditch, J., AJ, submitted (1997). |
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