Complex Organic Molecules at High Spatial Resolution Toward Orion-KL II: Kinematics

Abstract

It has recently been suggested that chemical processing can shape the spatial distributions of complex molecules in the Orion-KL region and lead to the nitrogen-oxygen "chemical differentiation" seen in previous observations of this source. Orion-KL is a very dynamic region, and it is therefore also possible that physical conditions can shape the molecular distributions in this source. Only high spatial resolution observations can provide the information needed to disentangle these effects. Here we present millimeter imaging studies of Orion-KL at various beam sizes using the Combined Array for Research in Millimeter-Wave Astronomy (CARMA). We compare molecular images with high spatial resolution images that trace the temperature, continuum column density, and kinematics of the source in order to investigate the effects of physical conditions on molecular distributions. These observations were conducted at λ= 3 mm and included transitions of ethyl cyanide [C2H5CN], methyl formate [HCOOCH3], formic acid [HCOOH], acetone [(CH3)2CO], SiO, and methanol [CH3OH]. We find differences in the molecular distributions as a function of each of these factors. These results indicate that acetone may be produced by chemical processing and is robust to large changes in physical conditions, while formic acid is readily destroyed by gas-phase processing in warm and dense regions. We also find that while the spatial distributions of ethyl cyanide and methyl formate are not distinct as is suggested by the concept of "chemical differentiation", local physical conditions shape the small-scale emission structure for these species.

Accepted for publication in the Astrophysical Journal Supplements; Part 2 of a 2 paper series; 35 pages

References in corpus (7)

• Complex Chemistry in Star-Forming Regions: An Expanded Gas-Grain Warm-up Chemical Model
• A Multi-Epoch Study of the Radio Continuum Emission of Orion Source I: Constraints on the Disk Evolution of a Massive YSO and the Dynamical History of Orion BN/KL
• Unveiling Sources of Heating in the Vicinity of the Orion BN/KL Hot Core as Traced by Highly Excited Inversion Transitions of Ammonia
• High Resolution $\lambda$=1mm CARMA Observations of Large Molecules in Orion-KL
• Complex Organic Molecules at High Spatial Resolution Toward Orion-KL I: Spatial Scales
• Hubble Space Telescope NICMOS Polarization Measurements of OMC-1
• A High Spatial Resolution Study of the λ=3 mm Continuum of Orion-KL

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• 13C-methyl formate: observations of a sample of high mass star-forming regions including Orion-KL and spectroscopic characterization
• Complex Organic Molecules at High Spatial Resolution Toward Orion-KL I: Spatial Scales
• Chemistry of the High-Mass Protostellar Molecular Clump IRAS 16562-3959
• Chemical composition in the IRAS 16562--3959 high-mass star-forming region
• A Q-band line survey towards Orion KL using the Tianma radio telescope
• SPARKS II.: Complex organic molecules in accretion shocks around a hot core precursor
• The distribution of deuterated formaldehyde within Orion-KL
• CARMA $\lambda$ = 1 cm Spectral Line Survey of Orion-KL
• Millimeter-wave spectrum of 2-propanimine
• Comparing Complex Chemistry in Neighboring Hot Cores: NOEMA Studies of W3(H${}_2$O) and W3(OH)
• The LMT 2 millimeter receiver system (B4R). II. Science demonstration observations toward Orion-KL/OMC-1
• Digging into the Massive Protostar S255IR NIRS3: A Study of Nitrogen-Bearing Molecules and Their Prebiotic Chemistry