EDP Sciences
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Volume 414, Number 1, January IV 2004
Page(s) 223 - 233
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20034015

A&A 414, 223-233 (2004)
DOI: 10.1051/0004-6361:20034015

On the light echo in V838 Mon

R. Tylenda

N. Copernicus Astronomical Center, Department for Astrophysics, Rabianska 8, 87-100 Torun, Poland
(Received 26 June 2003 / Accepted 30 September 2003)

We present a theoretical outline of the light echo phenomenon and results of simple numerical simulations and we study the available images of the light echo in V838 Mon obtained with HST. An investigation of the observed expansion of the light echo leads us to conclude that the distance to V838 Mon is $\ga$5 kpc. From an analysis of the inner bright echo rim we estimate the distance to be $8.0\,\pm\,2.0$ kpc. We also investigate the structure of the dust distribution in the vicinity of the object. We find no obvious signs of spherical symmetry in the resultant distribution. Near the central object there is a strongly asymmetric dust-free region which we interpret as produced by a fast wind from the V838 Mon system. The asymmetry would imply that V838 Mon is moving relative to the dusty medium. From these results we conclude that the dust illuminated by the light echo is of interstellar origin rather than produced by mass loss from V838 Mon in the past.

Key words: stars: individual: V838 Mon -- stars: distances -- stars: circumstellar matter -- ISM: reflection nebulae

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