Near-IR imaging towards a puzzling YSO precessing jet

TL;DR

This study presents high-resolution near-IR imaging of a massive young stellar object, revealing a precessing jet and complex shock-excited emission features, advancing understanding of intermediate-mass star formation.

Contribution

It provides one of the best-resolved images of a precessing jet in a massive YSO, combining detailed morphological analysis with proper motion data.

Findings

Detection of a twisted, cone-like nebula indicating a precessing jet

Identification of shock-excited H2 emission regions

Correlation of near-IR features with molecular outflows

Abstract

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, we found highly misaligned molecular outflows towards the infrared point source IRS. Using near-IR 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/northeast of 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-shaped feature composed by two arc-like features and a bow shock-like structure seen mainly in the Ks-band, which strongly suggests the presence of a precessing jet. An analysis of proper motions based on our Gemini observations and UKIDSS data gives additional support to the precession 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.