Chamaeleon DANCe

Abstract

Context. Chamaeleon is the southernmost low-mass star-forming complex within 200 pc from the Sun. Its stellar population has been extensively studied in the past, but the current census of the stellar content is not complete yet and deserves further investigation. Aims. We take advantage of the second data release of the Gaia space mission to expand the census of stars in Chamaeleon and to revisit the properties of the stellar populations associated to the Chamaeleon I (Cha I) and Chamaeleon II (Cha II) dark clouds. Methods. We perform a membership analysis of the sources in the Gaia catalogue over a field of 100 deg2 encompassing the Chamaeleon clouds, and use this new census of cluster members to investigate the 6D structure of the complex. Results. We identify 188 and 41 high-probability members of the stellar populations in Cha I and Cha II, respectively, including 19 and 7 new members. Our sample covers the magnitude range from G = 6 to G = 20 mag in Cha I, and from G = 12 to G = 18 mag in Cha II. We confirm that the northern and southern subgroups of Cha I are located at different distances (191.4−0.8+0.8 pc and 186.7−1.0+1.0 pc), but they exhibit the same space motion within the reported uncertainties. Cha II is located at a distance of 197.5−0.9+1.0 pc and exhibits a space motion that is consistent with Cha I within the admittedly large uncertainties on the spatial velocities of the stars that come from radial velocity data. The median age of the stars derived from the Hertzsprung-Russell diagram and stellar models is about 1−2 Myr, suggesting that they are somewhat younger than previously thought. We do not detect significant age differences between the Chamaeleon subgroups, but we show that Cha II exhibits a higher fraction of disc-bearing stars compared to Cha I. Conclusions. This study provides the most complete sample of cluster members associated to the Chamaeleon clouds that can be produced with Gaia data alone. We use this new census of stars to revisit the 6D structure of this region with unprecedented precision.

Probing protoplanetary disk evolution in the Chamaeleon II region

“…We checked the membership of each observed target by using distances from Gaia data releases and the recent membership analysis performed by Galli et al (2021, their Table A.2). We find that 19 disks included in our sample were confirmed as members by Galli et al (2021). We classify these sources as "Members" in Table 1 and we report the individual distances as estimated by Galli et al (2021).…”

“…We find that 19 disks included in our sample were confirmed as members by Galli et al (2021). We classify these sources as "Members" in Table 1 and we report the individual distances as estimated by Galli et al (2021). We also identified five sources, rejected or not included in the study of Galli et al (2021), as likely cluster members given their latest Gaia EDR3 distance (Gaia Collaboration 2021).…”

“…We classify these sources as "Members" in Table 1 and we report the individual distances as estimated by Galli et al (2021). We also identified five sources, rejected or not included in the study of Galli et al (2021), as likely cluster members given their latest Gaia EDR3 distance (Gaia Collaboration 2021). Their Gaia EDR3 distances lie less than 20 pc away from the average cluster distance.…”

χ1 Fornacis cluster DANCe

“…We selected the most likely members of the XFOR cluster based on Gaia-EDR3 data using the same methodology applied by our team to other young stellar groups (see e.g. Miret-Roig et al 2019;Galli et al 2020aGalli et al ,b, 2021. We summarise the main steps of our membership analysis in this section and refer the reader to the original papers (Sarro et al 2014;Olivares et al 2019) for further details on the methodology.…”

“…In this paper, we revisit the census of cluster members using Gaia-EDR3 data and combine our results with spectroscopic observations to revisit the cluster properties. This study is conducted as part of the Dynamical Analysis of Nearby Clusters (DANCe, Bouy et al 2013) project and follows a similar methodology applied to other stellar clusters in this series (Olivares et al 2019;Miret-Roig et al 2019;Galli et al 2020aGalli et al ,b, 2021.…”