EDP Sciences
Free access
Volume 446, Number 3, February II 2006
Page(s) 1095 - 1105
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20053951
A&A 446, 1095-1105 (2006)
DOI: 10.1051/0004-6361:20053951

Multiwavelength monitoring of BD+53°2790 , the optical counterpart to 4U 2206+54

P. Blay1, I. Negueruela2, P. Reig3, 4, M. J. Coe5, R. H. D. Corbet6, 7, J. Fabregat8 and A. E. Tarasov9

1  Institut de Ciència dels Materials, Universidad de Valencia, PO Box 22085, 46071 Valencia, Spain
    e-mail: pere.blay@uv.es
2  Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, EPSA, Universidad de Alicante, PO Box 99, 03080 Alicante, Spain
    e-mail: ignacio@dfists.ua.es
3  Foundation for Research and Technology-Hellas, 711 10 Heraklion, Crete, Greece
4  Physics Department, University of Crete, 710 03 Heraklion, Crete, Greece
    e-mail: pau@physics.uoc.gr
5  School of Physics and Astronomy, Southampton University, Southampton SO17 1BJ, UK
    e-mail: M.J.Coe@soton.ac.uk
6  X-ray Astrophysics Laboratory, Code 662, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA
7  Universities Space Research Association
    e-mail: corbet@milkyway.gsfc.nasa.gov
8  Observatori Astronómic, Universidad de Valencia, PO BOX 22085, 46071 Valencia, Spain
    e-mail: juan@pleione.oauv.uv.es
9  Crimean Astrophysical Observatory, Nauchny, Crimea, 334413, Ukraine
    e-mail: tarasov@crao.crimea.ua

(Received 29 July 2005 / Accepted 5 October 2005 )

We present the results of our long-term monitoring of BD+53°2790 , the optical counterpart to the X-ray source 4U 2206+54. Unlike previous studies that classify the source as a Be/X-ray binary, we find that its optical and infrared properties differ from those of typical Be stars: the variability of the V/R ratio is not cyclical; there are variations in the shape and strength of the H$\alpha$ emission line on timescales less than 1 day; and no correlation between the EW and the IR magnitudes or colors is seen. Our observations suggest that BD+53°2790 is very likely a peculiar O9.5V star. In spite of exhaustive searches we cannot find any significant modulation in any emission line parameter or optical/infrared magnitudes. Spectroscopy of the source extending from the optical to the K-band confirms the peculiarity of the spectrum: not only are the He lines stronger than expected for an O9.5V star but also there is no clear pattern of variability. The possibility that BD+53°2790 is an early-type analogue to He-strong stars (like $\theta^1$ Ori C) is discussed.

Key words: stars: early-type -- stars: emission-line, Be -- stars: magnetic fields -- stars: individual: BD$+53\degr$2790

SIMBAD Objects

© ESO 2006

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access.

An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account.
    In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.