An unbiased search for the signatures of protostars in the ρ  Ophiuchi A molecular cloud

Abstract

Abstract. We present an unbiased search for molecular hydrogen emission in the L1688 cloud within the ρ Ophiuchi molecular cloud complex. Our near-infrared survey covers a connected region of extent 35 × 35 . We detect several new H 2 flows but the total number of detected outflows is low and is consistent with the paucity of Class 0 and Class 1 sources in the molecular cloud. From the spatial distribution, their collimation and the individual shapes of the bow shocks, we suggest possible candidates for the outflow sources. Most of the candidate driving sources are deeply embedded in dense cores of the molecular cloud. A very young outflow arises from the newly discovered Class 0 source MMS 126. Two major outflows in the NE-SW direction arise from the YLW 15 and YLW 16 Class I sources. Three additional outflows, which both extend over several arcminutes, arise from the Class I sources YLW 31 and YLW 52. Flow directions are generally NE-SW, perpendicular to the elongation directions of the cloud filaments. The apparent extents of molecular flows are related to either the widths of cloud filaments or to the separation between filaments. The estimated jet power needed to continuously drive and excite the detected portions of the shocked H 2 outflows lies in the range 0.02−0.2 L . Given the critical dependence on the environment, however, the total sizes and powers of the outflows may be considerably larger.

Proper motions of molecular hydrogen outflows in theρOphiuchi molecular cloud

“…Archival SofI images (PID: 65.I-0576(A) and 67.C-0284(A)) obtained in July 2000 and August 2001, and published by Gómez et al (2003); Khanzadyan et al (2004) served as the first epoch data. The newly-acquired SofI images provided the second epoch to measure the proper motions of the H 2 emission-line features in MHOs.…”

“…Davis et al (2010) strictly defined molecular hydrogen emissionline objects (MHOs) as the near-infrared manifestations of outflows, and presented a comprehensive catalog of around 1000 MHOs. Deep, wide-field near-infrared imaging with the combination of narrow-band H 2 filter and the corresponding A&A 553, A41 (2013) filter for continuum emission such as a Ks filter has become a very efficient method to detect and identify MHOs (Stanke et al 2002;Khanzadyan et al 2004;Davis et al 2008;Froebrich et al 2011). Morphology, proper motion, as well as association with an HH object or CO outflow, can all provide information concerning the location of the driving source.…”

“…The relationship between the young stars and the outflow features is very complex in this region. Previous studies associated the outflow features with the young stars just based on the morphologies (Phelps & Barsony 2004;Gómez et al 2003;Khanzadyan et al 2004), which have large uncertainties. The kinematic information of the MHOs, including proper motions and radial velocities, will offer reliable evidence for the identification of the driving sources in this region.…”

Spatially resolved H2emission from a very low-mass star

“…This would lead to a precession period of about four years in order to generate the structures (A, B, and C) at each side of the so-called cavity (opening angle ∼65 • ). This period is too short when compared with typical jet fast precession periods (Rosen & Smith 2004;Caratti o Garatti et al 2008), and not consistent with the longer period suggested by the large-scale jet images (see f08-01 field in Khanzadyan et al 2004).…”

“…IRS 54 is known to possess a large-scale S-shaped bipolar jet as traced by a chain of H 2 knots 1 extending over several arcminutes (feature f08-01 in Khanzadyan et al 2004). From wide-field H 2 images, the jet appears to precess with a position angle (PA) changing from ∼72 • in the outermost knots passing through ∼78 • in the middle part of the jet down to 90 • closest to the source (MHO 2129; see also Fig.…”