Near-IR imaging towards a puzzling YSO precessing jet

S. PARON, C. FARIÑA, M. E. ORTEGA

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2016

0004-6361

The study of jets related to stellar objects in formation is important because it enables us to understand the history of how the stars have built up their mass. At present there are many studies concerning jets towards low-mass young stellar objects, while equivalent studies towards massive or intermediate-mass young stellar objects are scarce.In a previous study, based on 12CO J=3-2 and public near-IR data,we found highly misaligned molecular outflows towards the infrared point source UGPS J185808.46+010041.8 (IRS along this work),and some infrared features suggesting the existence of a precessing jet.Using near-infrared data acquired with Gemini-NIRI at the JHKs-broad-bands and narrow-bands centered at the emission lines of[FeII], H2 1-0 S(1), H2 2-1 S(1), Br-gamma, and CO 2-0 (bh), we studied the circumstellar environment of IRS with an angular resolution between 0.35" and 0.45".The emission in the JHKs-broad-bands shows, with great detail, the presence of a cone-like shape nebula extending to the north/northeastof the point source, which appears to be attached to it by a jet-like structure. In the three bands the nebula is resolved in a twisted-shapedfeature composed by two arc-like features and a bow shock-like structure seen mainly in the Ks-band, which strongly suggests the presenceof a precessing jet. An analysis of proper motions based on our Gemini observations and UKIDSS data gives additional support to theprecession scenario. We are presenting one of the best resolved cone-like nebula likely related to a precessing jet up to date.The analysis of the observed near-infrared lines shows that the H2 is collisionally excited, and the spatially coincidence of the [FeII] and H2 emissions in the closer arc-like feature suggests that this region is affected by a J-shock.  The second arc-like feature presents H2 emission without [FeII] which suggests the presence of a nondisociative C-shock or a less energetic J-shock. The H2 1-0 S(1) continuum subtracted image,reveals several knots and filaments at a larger spatial scale around IRS, in perfect matching with the distribution of the red and blueshifted molecular outflows discovered in our previous work. A not resolved system of YSOs is suggested to explain the distribution of the analyzed near-infrared features and the molecular outflows, which in turns explain the jet precession through tidal interactions.