Complex Organic Molecules at High Spatial Resolution Toward Orion-KL I: Spatial Scales

TL;DR

This study uses high-resolution millimeter-wave observations to map the spatial distribution of complex molecules in Orion-KL, revealing multiple emission components and informing chemical models of star-forming regions.

Contribution

First high-resolution mapping of multiple complex molecules in Orion-KL, showing their emission arises from diverse spatial scales and physical conditions.

Findings

Molecular emissions originate from multiple spatial components.

Complex molecules are distributed across various physical conditions.

Results impact understanding of chemical processes in star formation.

Abstract

Here we present high spatial resolution (<1 arcsecond) observations of molecular emission in Orion-KL conducted using the Combined Array for Research in Millimeter-Wave Astronomy (CARMA). This work was motivated by recent millimeter continuum imaging studies of this region conducted at a similarly high spatial resolution, which revealed that the bulk of the emission arises from numerous compact sources, rather than the larger-scale extended structures typically associated with the Orion Hot Core and Compact Ridge. Given that the spatial extent of molecular emission greatly affects the determination of molecular abundances, it is important to determine the true spatial scale for complex molecules in this region. Additionally, it has recently been suggested that the relative spatial distributions of complex molecules in a source might give insight into the chemical mechanisms that drive complex chemistry in star-forming regions. In order to begin to address these issues, this study seeks to determine the spatial distributions of ethyl cyanide [C2H5CN], dimethyl ether [(CH3)2O], methyl formate [HCOOCH3], formic acid [HCOOH], acetone [(CH3)2CO], SiO, methanol [CH3OH], and methyl cyanide [CH3CN] in Orion-KL at \lambda = 3 mm. We find that for all observed molecules, the molecular emission arises from multiple components of the cloud that include a range of spatial scales and physical conditions. Here we present the results of these observations and discuss the implications for studies of complex molecules in star-forming regions.