Volume 541, May 2012
|Number of page(s)||9|
|Section||Stellar structure and evolution|
|Published online||18 April 2012|
Discovery of a parsec-scale bipolar nebula around MWC 349A
1 Argelander-Institut für Astronomie,
Universität Bonn, Auf dem Hügel
71, 53121 Bonn, Germany
2 Sternberg Astronomical Institute, Lomonosov Moscow State University, Universitetskij Pr. 13, 119992 Moscow, Russia
3 Isaac Newton Institute of Chile, Moscow Branch, Universitetskij Pr. 13, 119992 Moscow, Russia
4 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, Bonn 53121, Germany
Accepted: 13 March 2012
We report the discovery of a bipolar nebula around the peculiar emission-line star MWC 349A using archival Spitzer Space Telescope 24 μm data. The nebula extends over several arcminutes (up to 5 pc) and has the same orientation and geometry as the well-known subarcsecond-scale (~400 times smaller) bipolar radio nebula associated with this star. We discuss the physical relationship between MWC 349A and the nearby B0 III star MWC 349B and propose that both stars were members of a hierarchical triple system, which was ejected from the core of the Cyg OB2 association several Myr ago and recently was dissolved into a binary system (now MWC 349A) and a single unbound star (MWC 349B). Our proposal implies that MWC 349A is an evolved massive star (likely a luminous blue variable) in a binary system with a low-mass star. A possible origin of the bipolar nebula around MWC 349A is discussed.
Key words: stars: individual: MWC 349A / stars: winds, outflows / stars: massive / binaries: general / circumstellar matter
© ESO, 2012
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