High-resolution spectroscopy of the δ Scuti star 44 Tauri: photospheric element abundances and mode identification
Abstract
Aims:We carried out a detailed spectroscopic study of the δ Sct star 44 Tau to investigate its element abundances and stellar parameters as well as to provide an identification of its non-radial oscillation modes.
Methods: We acquired high-resolution high-signal-to-noise ratio time-series spectroscopy of 44 Tau from two observing sites in Europe during a time span of 30 days. We determined atmospheric element abundances and stellar properties using spectroscopic methods. Due to the low value of v sin{i} the mode identification was carried out by applying the moment method.
Results: A very low value of the projected rotational velocity of v sin{i} = 2 ± 1 km s-1 was determined. We detected spectroscopically 12 independent frequencies between 6.8 and 11.6 d-1 and four combination frequencies by analyzing the line moments as well as the pixel-intensities across the profiles of carefully selected Fe absorption lines. The mode identification applying the moment method yielded six axisymmetric pulsation modes. Two frequencies are low-degree prograde pulsation modes. A rather low value of log g = 3.6 was determined implying an evolved evolutionary status of 44 Tau. The derived atmospheric element abundances are close to solar.
Conclusions: Our analysis revealed that 44 Tau is an exceptionally slowly rotating δ Scuti star pulsating with a rich spectrum of axisymmetric pulsation modes. This simplifies the seismic modeling since rotational perturbations of higher order can be neglected.
- Publication:
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Astronomy and Astrophysics
- Pub Date:
- August 2007
- DOI:
- 10.1051/0004-6361:20077201
- Bibcode:
- 2007A&A...471..237Z
- Keywords:
-
- techniques: spectroscopic;
- line: profiles;
- stars: abundances;
- stars: oscillations;
- stars: variables: δ Scuti;
- stars: individual: HD26322 = 44 Tau