AAS 206th Meeting, 29 May - 2 June 2005
Session 35 Stars
Poster, Wednesday, 10:00am-7:00pm, Thursday, 9:20am-2:00pm, June 1, 2005, Ballroom A

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[35.02] The spectral evolution of V838 Moncerotis

M. T. Rushton, A. Evans, B. Smalley, J. Th. van Loon (Keele University), T. R. Geballe (Gemini), S. P. S. Eyres (Central Lancashire)

We present the results of our spectroscopic monitoring campaign of the unusual eruptive variable V838 Monocerotis. V838 Mon erupted in early-2002 and quickly transformed from a G-K type star into the coolest known supergiant. Since then the spectrum has been dominated by strong bands of H2O and CO and superficially resembles that of an L dwarf. However, other features are also present, including remarkably strong atomic lines and bands of metal oxides. Currently both circumstellar and photospheric material contribute significantly to the observed spectrum. The spectrum is still changing rapidly; atomic lines displaying inverse P Cygni profiles have emerged; the CO absorption lines are variable and show multiple velocity components; while at the same time other species are observed in emission. The cause of the eruptions is not known for certain. There are similarities between V838 Mon and thermal pulse objects, but there are also many differences. Accretion models, involving stellar mergers and planetary collisions have been put forward to explain its behaviour. It is probable V838 Mon belongs to a new class of object.

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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.