A Protostellar Jet Emanating from a Hypercompact HII Region

Abstract

We present radio continuum observations of the high-mass young stellar object (HMYSO) G345.4938+01.4677 made using the Australia Telescope Compact Array (ATCA) at 5, 9, 17, and 19 GHz. These observations provide definite evidence that the outer and inner pairs of radio lobes consist of shock ionized material being excited by an underlying collimated and fast protostellar jet emanating from a hypercompact HII region. By comparing with images taken 6 yr earlier at 5 and 9 GHz using the same telescope, we assess the proper motions of the radio sources. The outer West and East lobes exhibit proper motions of $64\pm 12$ and $48\pm 13$ milliarcsec yr${}^{-1}$, indicating velocities projected in the plane of the sky and receding from G345.4938+01.4677 of $520$ and $390$ km s${}^{-1}$, respectively. The internal radio lobes also display proper motion signals consistently receding from the HMYSO, with magnitudes of $17\pm 11$ and $35\pm 10$ milliarcsec yr${}^{-1}$ for the inner West and East lobes, respectively. The morphology of the outer West lobe is that of a detached bow shock. At 17 and 19 GHz, the outer East lobe displays an arcuate morphology also suggesting a bow shock. These results show that disk accretion and jet acceleration --- possibly occurring in a very similar way compared with low-mass protostars --- is taking place in G345.4938+01.4677 despite the presence of ionizing radiation and the associated hypercompact HII region.

Accepted in the Astrophysical Journal. 36 pages, 9 figures

References in corpus (18)

• Which jet launching mechanism(s) in TTauri stars?
• Three-dimensional simulation of massive star formation in the disk accretion scenario
• A hot compact dust disk around a massive young stellar object
• A Keplerian-like disk around the forming O-type star AFGL 4176
• The Luminosity Functions and Timescales of MYSOs and Compact HII regions
• A search for ionized jets towards massive young stellar objects
• The RMS Survey: Mid-Infrared Observations of Candidate Massive YSOs in the Southern Hemisphere
• A near-IR spectroscopic survey of massive jets towards EGOs
• Outflow-Confined H II Regions. I. First Signposts of Massive Star Formation
• A String of Radio Emission Associated with IRAS 16562-3959: A Collimated Jet Emanating from a Luminous Massive YSO
• The Gould Belt Very Large Array Survey IV: The Taurus-Auriga complex
• The Collimated Jet Source in IRAS 16547-4247: Time Variation, Possible Precession, and Upper Limits to the Proper Motions Along the Jet Axis
• Search for ionized jets towards high-mass young stellar objects
• Time Variation in G24.78+0.08 A1: Evidence for an Accreting Hypercompact H II Region?
• Observing the onset of outflow collimation in a massive protostar
• Tracing jet emission at the base of a high-mass YSO. First AMBER/VLTI observations of the Brγemission in IRAS 13481-6124
• Are molecular outflows around high-mass stars driven by ionization feedback?
• The Peculiar Radio Source M17 JVLA 35

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• The first interferometric survey in the K-band of massive YSOs. On the hot dust, ionised gas, and binarity at au scales
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