Sub-arcsec Observations of NGC 7538 IRS 1: Continuum Distribution and Dynamics of Molecular Gas

Abstract

We report new results based on the analysis of the SMA and CARMA observations of NGC 7538\,IRS\,1 at 1.3 and 3.4 mm with sub-arcsec resolutions. With angular resolutions $\sim$ 0\farcs7, the SMA and CARMA observations show that the continuum emission at 1.3 and 3.4 mm from the hyper-compact \ion{H}{2} region IRS\,1 is dominated by a compact source with a tail-like extended structure to the southwest of IRS\,1. With a CARMA B-array image at 1.3 mm convolved to 0\farcs1, we resolve the hyper-compact \ion{H}{2} region into two components: an unresolved hyper-compact core, and a north-south extension with linear sizes of $<270$ AU and $\sim$2000 AU, respectively. The fine structure observed with CARMA is in good agreement with the previous VLA results at centimeter wavelengths, suggesting that the hyper-compact \ion{H}{2} region at the center of IRS\,1 is associated with an ionized bipolar outflow. We image the molecular lines OCS(19-18) and CH${}_3$CN(12-11) as well as ${}^{13}$CO(2-1) surrounding IRS\,1, showing a velocity gradient along the southwest-northeast direction. The spectral line profiles in ${}^{13}$CO(2-1), CO(2-1), and HCN(1-0) observed toward IRS\,1 show broad redshifted absorption, providing evidence for gas infall with rates in the range of $3-10\times 10^{-3}$ M${}_{\odot }$ yr${}^{-1}$ inferred from our observations.

19 pages, 14 figures

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Cited by in corpus (10)

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• TADPOL: A 1.3 mm Survey of Dust Polarization in Star-forming Cores and Regions
• Radio Jets from Young Stellar Objects
• Multiplicity and disks within the high-mass core NGC7538IRS1: Resolving cm line and continuum emission at ~0.06"x0.05" resolution
• Hot Ammonia around O-type Young Stars. I. JVLA imaging of Ammonia (6,6) to (14,14) in NGC7538 IRS1
• Inferring the evolutionary stages of the internal structures of NGC 7538 S and IRS1 from chemistry
• Tightening the belt: Constraining the mass and evolution in SDC335
• NGC7538 IRS1 -- an O star driving an ionized jet and giant N-S outflow
• NGC 7538 IRS1: Interaction of a polarized dust spiral and a molecular outflow
• First detection of THz water maser in NGC7538-IRS1 with SOFIA and new 22 GHz e-MERLIN maps