We propose that the energy source of the outburst of V838 Mon and similar
objects is an accretion event, i.e., gravitational energy rather than
thermonuclear runaway. We show that the merger of two main sequence stars, of
masses 1.5 Mo and 0.1-0.5 Mo can account for the luminosity, large radius, and
low effective temperture of V838 Mon and similar objects. Subsequent cooling
and gravitational contraction lead such objects to move along the Hayashi
limit, as observed. By varying the masses and types of the merging stars, and
by considering slowly expanding, rather than hydrostatic, envelopes, this model
can account for a large range in luminosities and radii of such outburst
events.Comment: 9 page