ИСТИНА

V838 Mon is a peculiar red nova with an outburst accompanied by a light echo. Images of the light echo were taken on 29 nights between October 4, 2002 and October 21, 2009. The structure of the dust nebula surrounding V838 Mon and illuminated by the light echo was investigated using these and all published with a fixed date images. The shape, the dimension of the nebula and the star location within depend on a single parameter, distance to V838 Mon. With the adopted distance of 6 kpc, the model of the nebula looks like a disk of 3-4 pc in diameter with the frontal plane inclined by 15 degrees to the line of sight. V838 Mon is located inside the nebula at the depth of 2 pc under the plane along the line of sight and at the distance of 0.8 pc from its center. The structure of the nebula is non-uniform, and V838 Mon is located on a remote boundary of a dense dust heterogeneity. Structural details of the nebula are unrelated to the star's position. We also performed UBVRI photometry of surrounding stars in the 6' diameter field around V838 Mon. Spectra of 13 stars within the limits of light echo expansion radius were taken with the Russian 6 m telescope BTA. These stars are in the magnitude range 14.2 - 20.2 mag in the V band. The cluster contains only three B type stars discovered by Afsar and Bond. It turned out that components of V838 Mon system miss the spectrum - magnitude relation of the cluster and are located below it. The exploded B3V star is 0.97 mag below, and its companion B3 V engulfed in 2008 by the explosion remnant is 1.32 mag below in the V band. However, the light-echo model and identical color excesses confirm that V838 Mon components are located at the same distance as brighter cluster members. This means that bright cluster members are evolved main sequence stars, whereas the exploded component was a zero-age main sequence star and its B3V companion was below zero-age main sequence. These are important arguments confirming an early evolutionary stage of V838 Mon components.