Herbig-Haro Objects in the Off-Core Regions of the ρ Ophiuchi Dark Cloud

A wide-field survey for Herbig-Haro (HH) objects has been carried out in the Ophiuchi dark cloud, which extends the previous HH-surveyed area in this cloud from 1 deg2 to 11 deg2. Besides the confirmation of all the 10 known HH objects in the Oph cloud core (Reipurth, published in 1999), seven groups of HH objects, including HH 548, 549A-C, 550, 551, 552, 553A-E, and 554, are newly discovered in the off-core regions. The newly found HH objects concentrate in three regions, which are 2-3 pc away from the Oph dark cloud core. Among these, the three brightest objects, HH 549, 550, and 551, show characteristic HH morphologies of shock or knot with tail. HH 553 and 554 are located in the L1689N region, but they are unlikely driven by the well-known protostar IRAS 16293 2422. HH 550 and 551 are located more than 1 pc away from the cloud and possibly form a parsec-scale HH flow in Ophiuchus.