The detection of the rich p-mode spectrum and asteroseismology of Przybylski's star
Abstract
Aims: We investigate the oscillation spectrum of the most chemically-peculiar star in the sky, the rapidly-oscillating magnetic (roAp) star
Methods: High-precision radial velocity (RV) measurements, spanning four consecutive nights on 3-6 March, 2004, were obtained with the HARPS echelle-spectrometer at the ESO 3.6-m telescope, and photometric data were acquired during 6 nights of observations at the 24-inch telescope of Siding Spring Observatory. The RVs were measured using all spectral lines in the wavelength range 4400-5100 Å.
Results: We detected a rich spectrum of oscillation modes with semi-amplitudes ranging between 217 m s-1 and 1.6 m s-1. These belong to the complete spectrum of high-order, low ℓ = 0-2 modes, having a large spacing of overlineΔ ν = 64.07 ± 0.9 μHz. We calculated the nonadiabatic frequencies of axisymmetric high-order p-modes for main-sequence models with dipole magnetic fields of two chemical compositions (X,Z)= (0.7,0.02) and (X,Z) = (0.695,0.025). The former composition provided the best fit model and yielded stellar parameters of mass, M=1.525 ± 0.025 M_⊙, age = (1.5 ± 0.1) × 109 yr, effective temperature log T_e=3.821 ± 0.006, luminosity log L/L⊙= 0.797 ± 0.026, surface gravity log g=4.06 ±0.04, and polar magnetic field strength, Bp = 8.7± 0.3 kG. We are able to identify the modes of all detected oscillation frequencies. The photometric U and B light curves have maxima that precede the RV maximum by 0.16-0.19 in phase.
- Publication:
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Astronomy and Astrophysics
- Pub Date:
- November 2008
- DOI:
- 10.1051/0004-6361:200809890
- Bibcode:
- 2008A&A...490.1109M
- Keywords:
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- stars: chemically peculiar;
- stars: oscillations;
- stars: individual: <ASTROBJ>HD 101065</ASTROBJ>