EDP Sciences
Free access
Volume 403, Number 2, May IV 2003
Page(s) 653 - 658
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20030389

A&A 403, 653-658 (2003)
DOI: 10.1051/0004-6361:20030389

Confirmation of the Luminous Blue Variable nature of AFGL 2298

J. S. Clark1, V. M. Larionov2, 3, P. A. Crowther1, M. P. Egan4 and A. Arkharov5

1  Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, England, UK
2  Astronomical Institute of St. Petersburg University, Petrodvorets, Universitetsky pr. 28, 198504 St. Petersburg, Russia
3  Isaac Newton Institute of Chile, St. Petersburg Branch
4  US Air Force Research Laboratory, Space Vehicles Directorate, 29 Randolph Road, Hanscom AFB, MA 01731-3010, USA
5  Central Astronomical Observatory, 196140 St. Petersburg, Russia

(Received 22 January 2003 / Accepted 13 March 2003)

We present new photometric and spectroscopic observations of the stellar source AFGL 2298 (= IRAS 18576+0341 ) that has recently been proposed as a candidate Luminous Blue Variable (LBV). Our data confirm that the star is a highly luminous B supergiant which is both spectroscopically and photometrically variable. Assuming a distance of 10 kpc, comparison of the 2001 June data to synthetic spectra suggest stellar parameters of T=12.5 kK, log $(L/L_{\odot})=6.2$ and $\dot{M}=5\times10^{-5}~M_{\odot}$ yr -1. Data obtained in 2002 August indicate an increase in both temperature (=15 kK) and mass loss rate (= $1.2\times10^{-4}~M_{\odot}$ yr -1) at constant bolometric luminosity. These physical parameters place AFGL 2298 at the Humphreys-Davidson limit for the most luminous stars known. We conclude that the position of AFG 2298 in the HR diagram, the significant variability observed between 1999-2002 and presence of a massive ejection nebula are consistent with a classification of AFGL 2298 as a bona fide LBV.

Key words: stars: emission-line, Be -- stars: circumstellar matter

Offprint request: J. S. Clark, jsc@star.ucl.ac.uk

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