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Astron. Astrophys. 335, 1040-1048 (1998)

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Discovery of multiple non-axially symmetric near-IR bow shocks around the pre-main sequence binary AFGL 961

Colin Aspin

Nordic Optical Telescope, Apartado 474, E-38700 Santa Cruz de la Palma, Islas Canarias, Spain

Received 12 February 1998 / Accepted 14 April 1998


We present the discovery of multiple non-axially symmetric near-IR molecular hydrogen bow shocks around the high-mass pre-main sequence binary system AFGL 961. These data indicate that at periods one or both components of the binary have produced collimated outflows with associated shocks similar to those observed at visual wavelengths resulting in optical Herbig-Haro objects. We detect a minimum of four nebulous structures reminiscent of optical bow shocks together with five other diffuse objects with less well-defined morphology. The spatial location of the bow shocks and associated nebulous knots suggests that both components of the binary have, at times, actively driven outflows. At the present time, only the western component of the binary currently shows direct evidence of outflow activity in the form of 12CO emission bandheads. The timescale between the outbursts that drive the outflows and result in the creation of the NIR shock-excited nebulae is 300-500 years. This is similar to estimates made for related events in both optical Herbig-Haro sources and FU Orionis type stars.

Key words: circumstellar matter – stars: individual: AFGL 961 – stars: pre-main sequence – ISM: jets and outflows – infrared: ISM: lines and bands

Send offprint requests to: C. Aspin

© European Southern Observatory (ESO) 1998

Online publication: June 26, 1998