2014A&A...569L...3C -
Astronomy and Astrophysics, volume 569, L3-3 (2014/9-1)
V838 Monocerotis: the central star and its environment a decade after outburst.
CHESNEAU O., MILLOUR F., DE MARCO O., BRIGHT S.N., SPANG A., BANERJEE D.P.K., ASHOK N.M., KAMINSKI T., WISNIEWSKI J.P., MEILLAND A. and LAGADEC E.
Abstract (from CDS):
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. 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 8m unit telescopes between October 2011 and February 2012. The AMBER three-beam observations were obtained with the compact array (B≤35m) in April 2013 and the long array (B≤140m) in May 2014, using the 1.8m auxiliary telescopes. A significant new result is the detection of a compact structure around
V838 Mon, as seen from MIDI data. The extension of the structure increases from a FWHM of 25mas at 8µm to 70mas at 13µm. At the adopted distance of D=6.1±0.6kpc, the dust is distributed from about 150 to 400AU around
V838 Mon. 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±200R
☉ (3.5±1.0AU). 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.
Abstract Copyright:
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Journal keyword(s):
techniques: high angular resolution - stars: individual: V838 Monocerotis - circumstellar matter - stars: mass-loss
Simbad objects:
8
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