An ALMA Sub-arcsecond View of Outflows, Ionized Gas, and Spatially-Extended Complex Organic Chemistry in OB Cluster-forming Region G10.6-0.4
Abstract
While informative of the bulk chemical properties of massive young stellar objects (MYSOs), single-dish studies are unable to probe the significant chemical differentiation that occurs on small scales, and to date, only a handful of studies have been conducted at high spatial resolution. Such observations, which directly resolve the spatial differences between the emission of distinct species, are essential, as they allow us to unambiguously discern the regions traced by different molecular species and families of molecules, providing further insight into their formation processes and chemistry. To investigate this small-scale chemistry, we used ALMA 1.3 mm observations at 0.14" (700 AU) toward massive star-forming region G10.6-0.4 (hereafter "G10.6") to derive detailed rotational temperature and column density maps in a large sample of complex organic molecules (COMs) and warm gas tracers. Combined with our simultaneous observations of ionized gas in hydrogen recombination line H30α, our exquisite spatial resolution allows us to constrain the chemical influences of massive stellar feedback in the form of highly structured and inhomogeneous molecular gas, prominent spatial anti-correlations between molecular and ionized gas, and order-of-magnitude variations in physical gas conditions. In addition to identifying two molecular hot core-like structures, we find extensive complex organic chemistry in regions outside of these cores. The extended, highly-structured nature of both ionized and dense COM-rich gas throughout G10.6 has important implications for existing astrochemical models, which are unable to fully describe complex UC H II regions with strong external heating sources. We also see evidence for interaction between strong SiO outflows and N-bearing COM species in the form of elevated line widths and enhanced rotational temperatures. Overall, these results suggest that high spatial resolution observations of COM distributions serve not only as valuable tracers for physical and dynamical structures in MYSOs, but are crucial for understanding the chemical influence of massive stellar feedback on nearby dense gas.
- Publication:
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American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23521301L