Herbig-Haro Emission Associated with Molecular Outflow Sources

Abstract

The precise relationship between CO outflows from high luminosity young stellar objects (YSOs) and their associated optical outflow’s (HH objects and jets) is not well known. For this reason we have examined, by spectroscopy and imaging, the optical outflows from the high luminosity YSOs, LkHa 198 and Cep A. Both sources are thought to drive molecular outflows. For LkHo: 198, a Herbig Ae/Be star, we report that the bright HH object previously thought to be associated with it, is in fact, not related. This object appears to be part of an optical outflow whose source is a newly-discovered star located 5″ to the northeast. It is not certain which of the two stars drives the molecular outflow although the newly-discovered star appears to illuminate the “reflection loops” in this region. To the north of LkHα 198 is another Herbig Ae/Be star V376 Cass and we report the discovery of a number of nearby HH emission knots, some of which may be associated. Finally, in the case of Cep A, an embedded infrared (EIR) source, the discovery of a virtual ring of HH emission has important implications for our understanding of the outflow geometry. In particular we examine the question of a second outflow system and its possible orientation.