Evidence for variable outflows in the young stellar object V645 Cygni

Aims. As part of the Red MSX Source Survey of Massive Young Stellar Objects (MYSOs) we have conducted multi-wavelength follow up observations of the well-known object V645 Cygni. We present our data on this object, whose near-infrared spectrum is exceptional and place these in context with previous observations Methods. Our observations of V645 Cyg included near/mid infrared imaging observations, 13CO 2-1 line observations and high signal-to-noise velocity resolved near-infrared spectroscopy. Results. The spectrum shows P-Cygni hydrogen Brackett emission, consistent with a high velocity stellar wind. A red-shifted emission component to a number of near-IR emission lines was also uncovered. This is associated with a similar component in the Hα- line. V645 Cyg is also found to have variable CO first overtone bandhead emission. Conclusions. The data clearly indicate that the outflow of V645 Cyg is variable. The unidentified feature in a previously published optical spectrum is identified with a receding outflow at 2000 kms-1. The nature of this feature, which is found in hydrogen and helium atomic lines and CO molecular lines remains a puzzle. © ESO 2006.