AAS 205th Meeting, 9-13 January 2005
Session 29 Planetary Systems and Origins of Planetary Bodies
Oral, Monday, January 10, 2005, 10:00-11:30am, Town and Country

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[29.03] The planets-swallowing model for the outburst of V838~Mon

A. Retter (Pennsylvania State University), B. Zhang (University of Nevada), L. Siess (Université Libre de Bruxelles), A. Levinson (Tel Aviv University)

Understanding the nature of the multi-stage outburst of V838 Mon and similar objects is challenging. V838 Mon has recently recognized as the proto-type of a new class of objects which have red colors and large radii in eruption. We suggest that the outburst of V838 Mon was caused by the expansion of a giant star and the subsequent swallowing of three Jupiter-like planets. We show that during the eruption the luminosity of V838 Mon was super-Eddington, which can explain the fast rising times of the three peaks in the optical light curve. We used three different methods to estimate the location where the planets were consumed. There is a remarkable agreement between the values obtained from the luminosities of the peaks, from their rising time scale and from the Roche Lobe geometry. The conclusion drawn from the model is that the planets were consumed at a distance of a few solar radii from the core of the host giant star -- well inside its extended envelope. The planets-devouring model seems to give a satisfying explanation of the differences in the luminosities, widths and rising times of the three peaks in the light curve of V838 Mon as well as of the high ejecta mass. Within the model there are several indications that the host star has a solar-like mass. We further estimate that the number of stars that accrete planets in our galaxy is ~ 4 per year, however only ~ 8% of them are discovered, consistent with the observations. Our results suggest that the swallowing of planets probably has a significant impact on the evolution of stars and should be considered in theoretical models.

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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.