V838 monocerotis: the central star and its environment a decade after outburst

O. Chesneau*, F. Millour, O. De Marco, S. N. Bright, A. Spang, D. P K Banerjee, N. M. Ashok, T. Kamiński, J. P. Wisniewski, A. Meilland, E. Lagadec

*Corresponding author for this work

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Aims. V838 Monocerotis erupted in 2002, brightened in a series of outbursts, and eventually developed a spectacular light echo. A very red star emerged a few months after the outburst. The whole event has been interpreted as the result of a merger. Methods. We obtained near-and mid-IR interferometric observations of V838 Mon with the AMBER and MIDI recombiners located at the Very Large Telescope Interferometer (VLTI) array. The MIDI two-beam observations were obtained with the 8?m unit telescopes between October 2011 and February 2012. The AMBER three-beam observations were obtained with the compact array (B = 35 m) in April 2013 and the long array (B = 140m) in May 2014, using the 1.8 m auxiliary telescopes.Results. A significant new result is the detection of a compact structure around, as seen from MIDI data. The extension of the structure increases from a FWHM of 25 mas at 8 μ m to 70 mas at 13 μ m. At the adopted distance of D = 6.1 ± 0.6 kpc, the dust is distributed from about 150 to 400 AU around. The MIDI visibilities reveal a flattened structure whose aspect ratio increases with wavelength. The major axis is roughly oriented around a position angle of-10°, which aligns with previous polarimetric studies reported in the literature. This flattening can be interpreted as a relic of the 2002 eruption or as caused by the influence of the currently embedded B3V companion. The AMBER data provide a new diameter for the pseudo-photosphere, which shows that its diameter has decreased by about 40% in 10 yr, reaching a radius R = 750 ± 200 R (3.5 ± 1.0 AU). Conclusions. After the 2002 eruption, which was interpreted as the merging of two stars, it seems that the resulting source is relaxing to a normal state. The nearby environment exhibits an equatorial overdensity of dust up to several hundred AU.

Original languageEnglish
Article numberL3
Pages (from-to)1-5
Number of pages5
JournalAstronomy and Astrophysics
Publication statusPublished - Sep 2014

Bibliographical note

Copyright ESO 2014. First published in Astronomy and astrophysics 569, L3, 2014, published by EDP Sciences. The original publication is available at http://doi.org/10.1051/0004-6361/201424458


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