Volume 522, November 2010
|Number of page(s)||12|
|Section||Stellar structure and evolution|
|Published online||04 November 2010|
V4332 Sagittarii: a circumstellar disc obscuring the main object*
Department for Astrophysics, N. Copernicus Astronomical Center,
e-mail: firstname.lastname@example.org ; email@example.com ; firstname.lastname@example.org
Accepted: 28 July 2010
Context. V4332 Sgr experienced an outburst in 1994 whose observational characteristics in many respects resemble those of the eruption of V838 Mon in 2002. It has been proposed that these objects erupted because of a stellar-merger event.
Aims. Our aim is to derive, from observational data, information on the present (10–15 yrs after the outburst) nature and structure of the object.
Methods. We present and analyse a high-resolution (R ≈ 21000) spectrum of V4332 Sgr obtained with the Subaru Telescope in June 2009. Various components (stellar-like continuum, atomic emission lines, molecular bands in emission) in the spectrum are analysed and discussed. We also investigate a global spectral energy distribution (SED) of the object mostly derived from broadband optical and infrared photometry.
Results. The observed continuum resembles that of an ~M 6 giant. The emission features (atomic and molecular) are most probably produced by radiative pumping. The observed strengths of the emission features strongly suggest that we only observe a small part of the radiation of the main object responsible for pumping the emission features. An infrared component seen in the observed SED, which can be roughly approximated by two blackbodies of ~950 and ~200 K, is ~50 times brighter than the M 6 stellar component seen in the optical. This further supports the idea that the main object is mostly obscured for us.
Conclusions. The main object in V4332 Sgr, an ~M 6 (super)giant, is surrounded by a circumstellar disc, which is seen almost edge-on so the central star is obscured. The observed M 6 spectrum probably results from scattering the central star spectrum on dust grains at the outer edge of the disc.
Key words: stars: peculiar / stars: late-type / stars: individual: V4332 Sgr / circumstellar matter / line: identification
© ESO, 2010
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.