G11.92-0.61 MM 1 : a fragmented Keplerian disk surrounding a proto-O star
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We present high-resolution (~300 au) Atacama Large Millimeter/submillimeter Array observations of the massive young stellar object G11.92–0.61 MM 1. We resolve the immediate circumstellar environment of MM 1 in 1.3 mm continuum emission and CH3CN emission for the first time. The object divides into two main sources—MM 1a, which is the source of a bipolar molecular outflow, and MM 1b, located 0."57 (1920 au) to the southeast. The main component of MM 1a is an elongated continuum structure, perpendicular to the bipolar outflow, with a size of 0."141 × 0."050 (480 × 170 au). The gas kinematics toward MM 1a probed via CH3CN trace a variety of scales. The lower energy J = 12–11 K = 3 line traces extended, rotating gas within the outflow cavity, while the v8 = 1 line shows a clearly resolved Keplerian rotation signature. Analysis of the gas kinematics and dust emission shows that the total enclosed mass in MM 1a is 40 ± 5 M ⊙ (where between 2.2 and 5.8 M ⊙ is attributed to the disk), while MM 1b is <0.6 M ⊙. The extreme mass ratio and orbital properties of MM 1a and MM 1b suggest that MM 1b is one of the first observed examples of the formation of a binary star via disk fragmentation around a massive young (proto)star.
Ilee , J D , Cyganowski , C J , Brogan , C L , Hunter , T R , Forgan , D H , Haworth , T J , Clarke , C J & Harries , T J 2018 , ' G11.92-0.61 MM 1 : a fragmented Keplerian disk surrounding a proto-O star ' , Astrophysical Journal Letters , vol. 869 , no. 2 , L24 . https://doi.org/10.3847/2041-8213/aaeffc
Astrophysical Journal Letters
Copyright © 2018. The American Astronomical Society. All rights reserved. This work is made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at: https://doi.org/10.3847/2041-8213/aaeffc
DescriptionJ.D.I. is funded by the STFC (ST/R000549/1), and J.D.I. and C.J. Clarke are funded by the DISCSIM project, grant agreement 341137 (ERC-2013-ADG). C.J. Cyganowski is funded by the STFC (ST/M001296/1). D.H.F. is funded by the ECOGAL project, grant agreement 291227 (ERC-2011-ADG). T.J. Haworth is funded by an Imperial College Junior Research Fellowship. T.J. Harries is funded by the STFC (ST/M00127X/1).
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