The detection of the rich p-mode spectrum and asteroseismology of Przybylski's star ^*

¹ Astrophysical Research Center for the Structure and Evolution of the Cosmos, Sejong University, Seoul 143-747, Korea e-mail: davidm@sejong.ac.kr
² Astronomical Observatory, Odessa National University, Shevchenko Park, Odessa, 65014, Ukraine
³ Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778, Tautenburg, Germany e-mail: artie@tls-tautenburg.de
⁴ Astronomical Institute, School of Science, Tohoku University, Sendai 980-8578, Japan e-mail: saio@astr.tohoku.ac.jp
⁵ Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT, Australia e-mail: rshobb@gmail.com

Received: 2 April 2008
Accepted: 23 August 2008

Abstract

Aims. We investigate the oscillation spectrum of the most chemically-peculiar star in the sky, the rapidly-oscillating magnetic (roAp) star HD 101065.

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 –2 modes, having a large spacing of Hz. We calculated the nonadiabatic frequencies of axisymmetric high-order p-modes for main-sequence models with dipole magnetic fields of two chemical compositions and . The former composition provided the best fit model and yielded stellar parameters of mass, , age = (1.5 ± 0.1) 10⁹ yr, effective temperature , luminosity , surface gravity , and polar magnetic field strength, Bp = 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.