IRAM-30m large scale survey of $^{12}$CO(2-1) and $^{13}$CO(2-1) emission in the Orion molecular cloud

TL;DR

This survey of the Orion molecular cloud using IRAM 30m telescope maps $^{12}$CO and $^{13}$CO emissions, revealing complex structures, estimating mass and age, and analyzing the role of magnetic fields and feedback in star formation.

Contribution

First large-scale high-resolution survey of Orion in $^{12}$CO and $^{13}$CO (2-1) lines providing detailed structural and kinematic data.

Findings

Cloud mass estimated at 7700 solar masses.

Magnetic fields significantly support the cloud structure.

HII region feedback is inefficient in triggering star formation.

Abstract

Using the IRAM 30m telescope we have surveyed a $1\times0.8^{\circ}$ part of the Orion molecular cloud in the $^{12}$CO and $^{13}$CO (2-1) lines with a maximal spatial resolution of $\sim$11" and spectral resolution of $\sim$ 0.4 km~s$^{-1}$. The cloud appears filamentary, clumpy and with a complex kinematical structure. We derive an estimated mass of the cloud of 7700 M$_{\text{Sun}}$ (half of which is found in regions with visual extinctions $A_V$ below $\sim$10) and a dynamical age for the nebula of the order of 0.2 Myrs. The energy balance suggests that magnetic fields play an important role in supporting the cloud, at large and small scales. According to our analysis, the turbulent kinetic energy in the molecular gas due to outflows is comparable to turbulent kinetic energy resulting from the interaction of the cloud with the HII region. This latter feedback appears negative, i.e. the triggering of star formation by the HII region is inefficient in Orion. The reduced data as well as additional products such as the column density map are made available online at http://userpages.irap.omp.eu/~oberne/Olivier_Berne/Data.