Main-Sequence Stellar Eruption Model for V838 Monocerotis

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 M 1 ≃ 1.5 M ☉ and M 2 ≃ 0.1-0.5 M ☉ , can account for the luminosity, large radius, and low effective temperature of V838 Mon and similar objects. 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.