Poster Presentation
ALMA Observations of Massive Young Stellar Objects in the Infrared Dark Cloud Core MSXDC G053.11+00.05 MM1
Presenter: Hyun-Jeong Kim (Seoul National University)
We report on ALMA observations of high-mass young stellar objects (YSOs) in the infrared dark cloud (IRDC) core MSXDC G053.11+00.05 MM1 at the distance of 1.7 kpc. At the center of the core, there are two YSOs separated by ~8" likely associated with a parsec-scale molecular hydrogen outflow discovered in near-infrared (H2 1-0 S(1) at 2.12 micron). With the total H2 outflow luminosity of >1 Lsun and spectral energy distributions as well as the detection of methanol masers, at least one of the two YSOs is supposed to be massive (M > 8 Msun). We observed the center of the core using ALMA Band 7 with a resolution of ~0.5" to resolve the two YSOs in sub-millimeter and to search for molecular line emission from outflow close to the YSOs or circumstellar disks. In this study, we present the preliminary results of the ALMA observations from which we have found a dust filament of < 0.1 pc containing a few dense cores at 870 micron continuum. While the brightest core is consistent with one of the two YSOs previously detected in near- and mid-infrared, the other cores are newly discovered implying their very deeply embedded states. In the molecular line observations, we have detected the emission of dense gas tracers such as H13CO+ or C17O as well as 13CO outflow emission with complicated morphology. The methanol line (CH3OH) tracing hot cores has also revealed velocity gradients in the dense cores. We present the physical properties of the dense cores, particularly the brightest one corresponding to the previously known YSO associated with the H2 outflow in near-infrared, and discuss some implications of high-mass star-formation process occurring in IRDC cores.
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