Re-visiting the Canis Major star-forming region with Gaia data release 3 data

Abstract

Context: The Canis Major (CMa) star-forming region, a remote molecular cloud complex within the recently discovered Radcliffe Wave, remains under-explored in the literature. Aims: We revisit the stellar census in the CMa region, characterizing its stellar population, kinematics, and age using recent astrometric and photometric data from the third data release of the Gaia space mission (Gaia DR3). Methods: We conducted a membership analysis of Gaia DR3 sources across a 16 deg$^2$ field encompassing the youngest subgroups in CMa. This new stellar census, combined with spectroscopic observations, allowed us to investigate the structure, kinematics, and age of this region. Results: We identified 1531 objects as members of the CMa region, confirming 401 previously known members and introducing 1130 new candidate members. These objects have magnitudes ranging from 10 to 18 mag in the G band from Gaia DR3. We identified two subgroups of CMa stars in our sample labelled as Cluster A and Cluster B. They are located at roughly the same distance ($d_{A} = 1150^{+79}_{-88}$ pc and $d_{B} = 1183^{+103}_{-108}$ pc) and exhibit similar space motions that can be derived thanks to the precise radial velocities obtained in this study. The subgroups have a mean isochronal age of about 2-3 Myr. However, based on infrared photometry we show that Cluster A has a higher fraction of disc-bearing stars suggesting that it could be somewhat younger than Cluster B. Conclusions: Our analysis provides new insights into the stellar population of the Canis Major region, by identifying new members, characterizing their kinematics, and assessing their evolutionary stages. Future studies incorporating additional data from upcoming Gaia data releases, multi-wavelength and high-resolution spectroscopic observations will be essential to further advance our understanding of the history of star formation in this region.