Issue |
A&A
Volume 503, Number 3, September I 2009
|
|
---|---|---|
Page(s) | 899 - 907 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361/200912312 | |
Published online | 09 July 2009 |
An analysis of a spectrum of V838 Monocerotis in October 2005
Department for Astrophysics, N. Copernicus Astronomical Center, Rabiańska 8, 87-100 Toruń, Poland e-mail: [tylenda;tomkam;schmidt]@ncac.torun.pl
Received:
9
April
2009
Accepted:
30
May
2009
Context. V838 Mon erupted at the beginning of 2002 becoming an extremely
luminous star with . Among various scenarios
proposed to explain the nature of the outburst, the most promising is
a stellar merger event.
Aims. We attempt to obtain information about the structure and evolution of the object in the decline from the 2002 eruption.
Methods. The results of spectroscopic observations of the object obtained in October 2005 with the Keck/HIRES instrument, presented in detail in Paper I, are analysed and discussed. Modelling of the observed line profiles has been used to constrain the physical parameters of the system.
Results. The kinematics of the atmosphere of V838 Mon is very complex.
Our analysis of the molecular bands and the P-Cyg profiles of
atomic lines shows that the object loses matter with a
velocity of up to 215 km s-1 and a rate of
yr-1.
In the profiles of some atomic lines, we have, however, found evidence of
matter infall. Moreover, a narrow absorption component, which is particularly strong
in some P-Cyg profiles, may indicate that a jet-like outflow has also been formed.
We show that the observed emission in the [
] lines and an
eclipse-like event observed in November/December 2006 was probably caused by
interactions of the expanding matter, ejected by V838 Mon in 2002, with
radiation from the B3V companion. In particular, the observed profiles of the
[
] lines can be easily modelled in this scenario and allow us to
estimate parameters of the system, such as the position of the B3V companion
relative to V838 Mon and the line of sight, density in the outflowing
matter, and mass lost in the 2002 eruption. The observed appearance of strong
Hα emission, just before and during the eclipse-like event, can be
interpreted as a result of the accretion of the outflowing
matter onto the B3V companion: the accreted matter, shocked above the stellar
surface, can be a source of extreme-UV and soft X-ray
radiation capable of ionizing and exciting H in the outflow.
Key words: stars: individual: V838 Monocerotis / stars: late-type / stars: early-type / stars: peculiar / stars: winds, outflows / line: profiles
© ESO, 2009
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