Proper motions of H2 jets and variability of young stars in the Serpens NW region.
Abstract (from CDS):
We present deep H2 1-0 S(1) line and continuum images as well as K-band proper-motion data on a system of emission knots in the Serpens NW region. Our data demonstrate that the jet outlined by these knots originates in knot ``a'' of the SMM 9 molecular clump in Serpens NW. Kinematic indications for remnants of molecular material being expelled from the star EC 37 were found. The jet associated with SMM 1 (FIRS1) was shown indeed to move in the direction suggested by its morphology. The faint star (EC 41) seen in the near-infrared close to the apex of that jet is almost certainly not identical with the driving source of the outflow. Extremely red stars, associated with some nebulosity, were found very close to the positions of the outflow sources S68 N/SMM 9 and SMM 10, suggesting that these stars found in the K band are identical to the objects detected at submillimeter wavelengths. We also report on the photometric monitoring of the Serpens Deeply Embedded Outburst Star (DEOS), discovered in 1995 and other young stars in Serpens. After an initial steeper drop in brightness by 0.84 mag in the first 290 days after the recorded maximum, the DEOS brightness is now decreasing at a slower average rate of 0.33 mag.yr–1. Its spectrum has changed since the time of discovery and now shows faint indications of CO band head absorption. The cometary nebula EC 53 (associated with SMM 5) shows repeated outbursts between 1994 and 1998; a periodicity of about 550 days is suggested. This Class I source is probably an EX Orionis variable.