Comparing the spatial and kinematic distribution of gas and young stars around the shell-like structure in the CMa OB1 association

TL;DR

This study investigates the spatial and kinematic relationships between gas and young stars in the CMa OB1 region, revealing correlations that support a history of successive supernova events shaping the shell-like structure.

Contribution

It provides new molecular cloud maps and kinematic data for the CMa OB1 region, linking YSO distribution with cloud morphology and dynamics, and supports a supernova-driven formation scenario.

Findings

YSOs spatially coincide with dense gas cores

Cloud kinematics show signatures of star formation processes

The structure is consistent with a supernova relic scenario

Abstract

The relationship between young stellar clusters and respective parental molecular clouds is still an open issue: for instance, are the similarities between substructures of clouds and clusters just a coincidence? Or would they be the indication of a physical relationship? In order to address these issues, we have studied the CMa OB1/R1 region that shows evidence for a complex star formation history. We obtained molecular clouds mapping with the IRAM-30 metre telescope to reveal the physical conditions of an unexplored side of the CMa region aiming to compare the morphology of the clouds with the distribution of the young stellar objects (YSOs). We also study the clouds kinematics searching for gradients and jet signatures that could trace different star formation scenarios. The YSOs were selected on the basis of astrometric data from Gaia EDR3 that characterise the moving groups. The distance of 1099$_{-24}^{+25}$ pc was obtained for the sample, based on the mean error-weighted parallax. Optical and near-infrared photometry is used to verify the evolutionary status and circumstellar characteristics of the YSOs. Among the selected candidates we found 40 members associated with the cloud: 1 Class I, 11 Class II, and 28 Class III objects. Comparing the spatial distribution of the stellar population with the cores revealed by the 13CO map, we verify that peaks of emission coincide with the position of YSOs confirming the association of these objects to their dense natal gas. Our observations support the large-scale scenario of the CMa shell-like structure formed as a relic of successive supernova events.