Subarcsecond Imaging of the NGC 6334 I(n) Protocluster: Two Dozen Compact Sources and a Massive Disk Candidate

Abstract

Using the Submillimeter Array (SMA) and Karl G. Jansky Very Large Array, we have imaged the massive protocluster NGC 6334 I(N) at high angular resolution (0. 5 ∼ 650 AU) from 6 cm to 0.87 mm, detecting 18 new compact continuum sources. Three of the new sources are coincident with previously identified H 2 O masers. Together with the previously known sources, these data bring the number of likely protocluster members to 25 for a protostellar density of ∼700 pc −3 . Our preliminary measurement of the Q-parameter of the minimum spanning tree is 0.82-close to the value for a uniform volume distribution. All of the (nine) sources with detections at multiple frequencies have spectral energy distributions consistent with dust emission, and two (SMA 1b and SMA 4) also have long wavelength emission consistent with a central hypercompact H ii region. Thermal spectral line emission, including CH 3 CN, is detected in six sources: LTE model fitting of CH 3 CN (J = 12-11) yields temperatures of 72-373 K, confirming the presence of multiple hot cores. The fitted LSR velocities range from −3.3 to −7.0 km s −1 , with an unbiased mean square deviation of 2.05 km s −1 , implying a protocluster dynamical mass of 410 ± 260 M . From analysis of a wide range of hot core molecules, the kinematics of SMA 1b are consistent with a rotating, infalling Keplerian disk of diameter 800 AU and enclosed mass of 10-30 M that is perpendicular (within 1• ) to the large-scale bipolar outflow axis. A companion to SMA 1b at a projected separation of 0. 45 (590 AU; SMA 1d), which shows no evidence of spectral line emission, is also confirmed. Finally, we detect one 218.4400 GHz and several 229.7588 GHz Class-I CH 3 OH masers.

High-mass Star Formation through Filamentary Collapse and Clump-fed Accretion in G22

“…(Cyganowski et al 2011(Cyganowski et al , 2012. However, maser emission of the CH 3 OH(4 2,2 -3 1,2 ) transition at 218.440 GHz has, to our knowledge, only been tentatively detected in DR21 (OH) by Zapata et al (2012) and in NGC 6334 I(N) by Hunter et al (2014) prior to this work. Population inversion for the 218.440 GHz transition has been predicted in maser models (Voronkov et al 2012).…”

Tightening the belt: Constraining the mass and evolution in SDC335

“…NGC 6334 I(N), hereafter simply I(N), is an IRDC at a distance of 1.3 kpc and displays seven compact millimetre continuum sources within a projected diameter of 0.1 pc at 2 resolution. In addition, in their study Hunter et al (2014) find 25 likely protostellar objects associated within a physical radius of 0.21 pc at 1.3 mm.…”

“…A second comparable region is the NGC 6334 I(N) protocluster, which has been well studied at mm wavelengths, most recently by Hunter et al (2014). NGC 6334 I(N), hereafter simply I(N), is an IRDC at a distance of 1.3 kpc and displays seven compact millimetre continuum sources within a projected diameter of 0.1 pc at 2 resolution.…”

Radiation-hydrodynamical simulations of massive star formation using Monte Carlo radiative transfer – II. The formation of a 25 solar-mass star

“…We note that Ilee et al (2016), Johnston et al (2015) and Chen et al (2016) identify Keplerian rotation in their observations of massive discs. However the observational measurements of the disc kinematics are complicated by the fact that they are obtained from molecular line tracers that may also simultaneously probe the rotating and infalling envelopes (for example Hunter et al (2014) observed a combination of Keplerian rotation and infall). In order to make a more realistic comparison between the model and observations it is necessary to compute synthetic observations from the model and test the model more directly via molecular line profiles (see Section 5.5).…”