Sustaining Star Formation in the Galactic Star Cluster M 36?
Abstract
We present comprehensive characterization of the Galactic open cluster M 36. Some 200 member candidates, with an estimated contamination rate of ∼8%, have been identified on the basis of proper motion and parallax measured by the Gaia DR2. The cluster has a proper motion grouping around ( ${\mu }_{\alpha }\cos \delta =-0.15\pm 0.01$ <!-- --> mas yr-1, and μδ = - 3.35 ± 0.02 mas yr-1), distinctly separated from the field population. Most member candidates have parallax values 0.7-0.9 mas, with a median value of 0.82 ± 0.07 mas (distance ∼1.20 ± 0.13 kpc). The angular diameter of $27^{\prime} \pm 0\buildrel{\,\prime}\over{.} 4$ <!-- --> determined from the radial density profile then corresponds to a linear extent of 9.42 ± 0.14 pc. With an estimated age of ∼15 Myr, M 36 is free of nebulosity. To the southwest of the cluster, we discover a highly obscured (AV up to ∼23 mag), compact (∼ $1\buildrel{\,\prime}\over{.} 9\times 1\buildrel{\,\prime}\over{.} 2$ <!-- --> ) dense cloud, within which three young stellar objects in their infancy (ages ≲0.2 Myr) are identified. The molecular gas, 3.6 pc in extent, contains a total mass of (2-3) × 102 M⊙, and has a uniform velocity continuity across the cloud, with a velocity range of -20 to -22 km s-1, consistent with the radial velocities of known star members. In addition, the cloud has a derived kinematic distance marginally in agreement with that of the star cluster. If physical association between M 36 and the young stellar population can be unambiguously established, this manifests a convincing example of prolonged star formation activity spanning up to tens of Myr in molecular clouds.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2021
- DOI:
- 10.3847/1538-4357/abded4
- arXiv:
- arXiv:2101.09445
- Bibcode:
- 2021ApJ...910...80P
- Keywords:
-
- Open star clusters;
- Stellar kinematics;
- Stellar dynamics;
- Pre-main sequence stars;
- Extinction;
- Molecular clouds;
- 1160;
- 1608;
- 1596;
- 1290;
- 505;
- 1072;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 24 pages, 14 figures, 4 tables