Volume 446, Number 3, February II 2006
|Page(s)||1095 - 1105|
|Section||Stellar structure and evolution|
|Published online||20 January 2006|
Multiwavelength monitoring of BD +53°2790, the optical counterpart to 4U 2206+54
Institut de Ciència dels Materials, Universidad de Valencia, PO Box 22085, 46071 Valencia, Spain e-mail: email@example.com
2 Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, EPSA, Universidad de Alicante, PO Box 99, 03080 Alicante, Spain e-mail: firstname.lastname@example.org
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: email@example.com
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: firstname.lastname@example.org
8 Observatori Astronómic, Universidad de Valencia, PO BOX 22085, 46071 Valencia, Spain e-mail: email@example.com
9 Crimean Astrophysical Observatory, Nauchny, Crimea, 334413, Ukraine e-mail: firstname.lastname@example.org
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 Hα 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 Ori C) is discussed.
Key words: stars: early-type / stars: emission-line, Be / stars: magnetic fields / stars: individual: BD +53°2790
© ESO, 2006
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.