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Title: Isolated Massive Star Formation in G28.20-0.05
Abstract We report high-resolution 1.3 mm continuum and molecular line observations of the massive protostar G28.20-0.05 with Atacama Large Millimeter/submillimeter Array. The continuum image reveals a ring-like structure with 2000 au radius, similar to morphology seen in archival 1.3 cm Very Large Array observations. Based on its spectral index and associated H30αemission, this structure mainly traces ionized gas. However, there is evidence for ∼30M⊙of dusty gas near the main millimeter continuum peak on one side of the ring, as well as in adjacent regions within 3000 au. A virial analysis on scales of ∼2000 au from hot core line emission yields a dynamical mass of ∼80M⊙. A strong velocity gradient in the H30αemission is evidence for a rotating, ionized disk wind, which drives a larger-scale molecular outflow. An infrared spectral energy distribution (SED) analysis indicates a current protostellar mass ofm*∼ 40M⊙forming from a core with initial massMc∼ 300M⊙in a clump with mass surface density of Σcl∼ 0.8 g cm−2. Thus the SED and other properties of the system can be understood in the context of core accretion models. A structure-finding analysis on the larger-scale continuum image indicates G28.20-0.05 is forming in a relatively isolated environment, with no other concentrated sources, i.e., protostellar cores, above ∼1M⊙found from ∼0.1 to 0.4 pc around the source. This implies that a massive star can form in relative isolation, and the dearth of other protostellar companions within the ∼1 pc environs is a strong constraint on massive star formation theories that predict the presence of a surrounding protocluster.  more » « less
Award ID(s):
2206450
PAR ID:
10559041
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ;
Publisher / Repository:
AAS/IOP
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
939
Issue:
2
ISSN:
0004-637X
Page Range / eLocation ID:
120
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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