Towards an understanding of the Of?p star HD191612: phase-resolved multiwavelength observations
Abstract
We present the analysis of phase-resolved X-ray and optical observations of the peculiar hot star HD191612 (Of?p). This star is known to display line-profile variations that are recurrent with a period of 538d and its spectrum was found to present the signature of a magnetic field. In the X-rays, it is slightly overluminous compared to the canonical LX/LBOL) relation and appears brighter when the optical lines are strongest. Our XMM-Newton observations further reveal that the X-ray spectrum of HD191612 exhibits rather broad lines and is dominated by a `cool' (0.2-0.6keV) thermal component, two characteristics at odds with the proposed magnetic rotator model. We also report for the first time the low-level variability of the metallic (absorption/emission) lines and HeII absorptions that appear to be associated with radial-velocity shifts. Finally, we compare our results with observations of the early-type stars and discuss several possible scenarios.
Based on observations collected at the Haute-Provence Observatory (France) and with XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA). E-mail: naze@astro.ulg.ac.be ‡ Post-doctoral Researcher FNRS (Belgium). § Research Associate FNRS (Belgium). ¶ Operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- February 2007
- DOI:
- 10.1111/j.1365-2966.2006.11270.x
- arXiv:
- arXiv:astro-ph/0611230
- Bibcode:
- 2007MNRAS.375..145N
- Keywords:
-
- stars: early-type;
- stars: individual: HD191612;
- X-rays: individual: HD191612;
- X-rays: stars;
- Astrophysics
- E-Print:
- 10p, 10 fig, accepted for publication in MNRAS (www.blackwell-synergy.com)