S-269-IRS-2 - A MASSIVE YOUNG STELLAR OBJECT POWERING HERBIG-HARO EMISSION

Near-IR images of S 269-IRS2 indicate that this young source is double with a projected separation of 4''.1 (2.45 10(17) cm) at a position a ngle of 90 degrees. The near-IR colours of both sources denote an infr ared excess and, therefore, their very young nature. The western sourc e, IRS2w, is the reddest one and is only detected at lambda greater th an or similar to 2 mu m. We believe that IRS2w is associated with the young IRAS source 06117 + 1350 and with the H2O and OH masers detected in the region. The total integrated infrared luminosity is 7.1 10(4) L. Optical CCD images reveal a pure emission line condensation close t o IRS2 and projected against the S 269 HII region. These images and sp ectroscopic data demonstrate that this condensation is shock excited. The condensation, designated HH 191, is to our knowledge the most dist ant HH object detected so far. It presents blueshifted radial velociti es up to about 400 km/s with respect to the underlying HII region. PV diagrams and integrated line profiles from HH 191 suggest that the HH object is generated in a bow shock. Using published bow shock models w e estimate a shock velocity of about 570 km/s. HH 191 is probably powe red by the high luminosity object IRS2w. All the characteristics of th e IRS2w/HH 191 system make it one of the extremest cases known among t he HH objects and their exciting sources.