A Jet-like Outflow toward the High-Mass (Proto)stellar Object IRAS 18566+0408

Abstract

We performed interferometric observations of a high-mass protostellar candidate IRAS 18566+0408 in the \nh3 (J,K)=(1,1), (2,2) and (3,3) inversion transitions, the SiO J=2-1 and HCN J=1-0 lines, and the 43 and 87 GHz continuum emission using the VLA and OVRO. The 87 GHz continuum emission reveals two continuum peaks MM-1 and MM-2 along a molecular ridge. The dominant peak MM-1 coincides with a compact emission feature at 43 GHz, and arises mostly from the dust emission. For dust emissivity index $\beta$ of 1.3, the masses in the dust peaks amount to 70 \msun for MM-1, and 27 \msun for MM-2. Assuming internal heating, the central luminosities of MM-1 and MM-2 are $6\times 10^4$ and $8\times 10^3$ \lsun, respectively. The SiO emission reveals a well collimated outflow emanating from MM-1. The jet-like outflow is also detected in \nh3 at velocities similar to the SiO emission. The outflow, with a mass of 27 \msun, causes significant heating in the gas to temperatures of 70 K, much higher than the temperature of $\lsim 15$ K in the extended core. Compact ($<3^{\prime \prime }$) and narrow line ($<1.5$ \kms-1) \nh3 (3,3) emission features are found associated with the outflow. They likely arise from weak population inversion in \nh3 similar to the maser emission. Toward MM-1, there is a compact \nh3 structure with a linewidth that increases from 5.5 \kms-1 FHWM measured at 3${}^{\prime \prime }$ resolution to 8.7 \kms-1\ measured at 1${}^{\prime \prime }$ resolution. This linewidth is much larger than the FWHM of $<$ 2 \kms-1 in the entire core, and does not appear to originate from the outflow. This large linewidth may arise from rotation/infall, or relative motions of unresolved protostellar cores.

19 pages, 9 figures. Accepted for publication in Astronomy and Astrophysics

References in corpus (1)

• Multiple Jets from the High-Mass (Proto)stellar Cluster AFGL5142

Cited by in corpus (6)

• Chemical Diversity in High-Mass Star Formation
• Spitzer-IRAC GLIMPSE of high mass protostellar objects II - SED modelling of a bonafide sample
• ATCA 3mm observations of NGC6334I and I(N): dense cores, outflows and an UCHII region
• A Search for H2CO 6cm Emission toward Young Stellar Objects III: VLA Observations
• Energetic radiation and the sulfur chemistry of protostellar envelopes: Submillimeter interferometry of AFGL 2591
• An H2CO 6cm Maser Pinpointing a Possible Circumstellar Torus in IRAS18566+0408