Pulsations of the Oe Star ζ Ophiuchi from MOST Satellite Photometry and Ground-based Spectroscopy

G. A. H. Walker, R. Kuschnig, J. M. Matthews, P. Reegen, T. Kallinger, E. Kambe, H. Saio, P. Harmanec, D. B. Guenther, A. F. J. Moffat, S. M. Rucinski, D. Sasselov, W. W. Weiss, D. A. Bohlender, H. Božić, O. Hashimoto, P. Koubský, R. Mann, D. Ruždjak, P. ŠkodaM. Šlechta, D. Sudar, M. Wolf, S. Yang

Veröffentlichungen: Beitrag in FachzeitschriftArtikelPeer Reviewed


Twenty-four days of highly precise Microvariability and Oscillations of Stars (MOST) satellite photometry obtained in mid-2004 of the rapidly rotating O9.5 V star ζ Oph have yielded at least a dozen significant oscillation frequencies between 1 and 10 cycles day-1, clearly indicating its relationship to β Cephei variables. Eight periods were found in He I λ4922 and Hβ line profile variations (LPV) of which six coincide with those from the MOST photometry. This unique photometric and spectroscopic detection of radial and nonradial pulsations leads to a plausible model in which high l-modes are excited when their frequencies in the corotating frame are similar to those of low-order radial modes. We propose that the dominant photometric 4.6 hr period (f1) corresponds to a radial first overtone excited by the κ-mechanism associated with the Fe opacity bump. No unambiguous rotational period can be identified in either the light curve or the LPV.

A Canadian Space Agency mission, jointly operated by Dynacon Inc., the University of Toronto Institute of Aerospace Studies, and the University of British Columbia with the assistance of the University of Vienna.
FachzeitschriftThe Astrophysical Journal
PublikationsstatusVeröffentlicht - 1 Apr. 2005

ÖFOS 2012

  • 103004 Astrophysik