Planck Cold Clumps in the lambda Orionis Complex. III. A chemical probe of stellar feedback on cores in the lambda Orionis cloud

TL;DR

This study investigates how stellar feedback from massive stars influences dense cores in the lambda Orionis cloud by analyzing molecular line data, revealing that UV radiation heats and alters core chemistry, suppressing star formation.

Contribution

It provides the first detailed chemical comparison of dense cores in the lambda Orionis cloud with Orion A and B, demonstrating the impact of stellar feedback on core properties.

Findings

C2H and HCN abundances are higher in lambda Orionis cores.

HDCO to H2CO ratios are lower in lambda Orionis, indicating warmer conditions.

Dense gas tracers are less frequently detected in lambda Orionis cores.

Abstract

Massive stars have a strong impact on their local environments. However, how stellar feedback regulates star formation is still under debate. In this context, we studied the chemical properties of 80 dense cores in the Orion molecular cloud complex composed of the Orion A (39 cores), B (26 cores), and lambda Orionis (15 cores) clouds using multiple molecular line data taken with the Korean Very Long Baseline Interferometry Network (KVN) 21-m telescopes. The lambda Orionis cloud has an H ii bubble surrounding the O-type star lambda Ori, and hence it is exposed to the ultraviolet (UV) radiation field of the massive star. The abundances of C2H and HCN, which are sensitive to UV radiation, appear to be higher in the cores in the lambda Orionis cloud than those in the Orion A and B clouds, while the HDCO to H2CO abundance ratios show an opposite trend, indicating a warmer condition in the lambda Orionis cloud. The detection rates of dense gas tracers such as the N2H+, HCO+, and H13CO+ lines are also lower in the lambda Orionis cloud. These chemical properties imply that the cores in the lambda Orionis cloud are heated by UV photons from lambda Ori. Furthermore, the cores in the lambda Orionis cloud do not show any statistically significant excess in the infall signature of HCO+ (1 - 0), unlike the Orion A and B clouds. Our results support the idea that feedback from massive stars impacts star formation in a negative way by heating and evaporating dense materials, as in the lambda Orionis cloud.