HD45314: a new gamma Cas analog among Oe stars


G. Rauw (1), Y. Naze (1), M. Spano (2), T. Morel (1), & A. ud-Doula (3)

1 - Institute of Astrophysics and Geophysics, Liege University, Belgium
2 - Geneva Observatory, University of Geneva, Switzerland
3 - Penn State Worthington Scranton, USA

Oe stars possibly form an extension to higher temperatures of the Be phenomenon, but it is still unclear whether these stars have disks. X-ray spectra could provide hints for interactions of the star with a putative surrounding disk. We obtained XMM-Newton observations of two Oe stars, HD45314 and HD60848. Spectra and light curves were extracted and analysed. Optical spectra were also obtained to support the X-ray observations. We find that both stars display very different X-ray properties. Whilst HD60848 has an X-ray spectrum and emission level typical for its spectral type, HD45314 displays a very hard X-ray emission, dominated by a thermal plasma with kT ~ 21 keV. Furthermore, HD45314 displays count rate variations by a factor 2 on timescales of ~ 1000s and a high log(L_X/L_bol) = -6.10 +/- 0.03. The X-ray properties of HD45314 indicate that this star is a new member of the class of gamma Cas analogs, the first one among the original category of Oe stars.

Reference: A&A Letter, in press
Status: Manuscript has been accepted

Weblink: http://arxiv.org/abs/1306.6520

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Email: rauw@astro.ulg.ac.be