The broadening of the main sequence in the open cluster M38
arXiv:2306.05737 · doi:10.1093/mnras/stad1754
Abstract
Our recent multi-band photometric study of the colour width of the lower main sequence of the open cluster M37 has revealed the presence of a sizeable initial chemical composition spread in the cluster. If initial chemical composition spreads are common amongst open clusters, this would have major implications for cluster formation models and the foundation of the chemical tagging technique. Here we present a study of the unevolved main sequence of the open cluster M38, employing Gaia DR3 photometry and astrometry, together with newly acquired Sloan photometry. We have analysed the distribution of the cluster's lower main sequence stars with a differential colour-colour diagram made of combinations of Gaia and Sloan magnitudes, like in the study of M37. We employed synthetic stellar populations to reproduce the observed trend of M38 stars in this diagram, and found that the observed colour spreads can be explained simply by the combined effect of differential reddening across the face of the cluster and the presence of unresolved binaries. There is no need to include in the synthetic sample a spread of initial chemical composition as instead necessary to explain the main sequence of M37. Further photometric investigations like ours, as well as accurate differential spectroscopic analyses on large samples of open clusters, are necessary to understand whether chemical abundance spreads are common among the open cluster population.
8 pages, 10 figures. Accepted for publication in MNRAS on 2023, June 07
References in corpus (17)
- Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
- The ACS Survey of Galactic Globular Clusters. I. Overview and Clusters Without Previous HST Photometry
- A double main sequence turn-off in the rich star cluster NGC 1846 in the Large Magellanic Cloud
- Multiple stellar populations in three rich Large Magellanic Cloud star clusters
- Ground-Based CCD Astrometry with Wide Field Imagers. I. [Observations just a few years apart allow decontamination of field objects from members in two Globular clusters.]
- 3D kinematics and age distribution of the Open Cluster population
- Open clusters in APOGEE and GALAH: Combining Gaia and ground-based spectroscopic surveys
- How stellar rotation shapes the colour magnitude diagram of the massive intermediate-age star cluster NGC 1846
- Exploring open cluster properties with Gaia and LAMOST
- Extended Main Sequence Turnoffs in Intermediate-Age Star Clusters: Stellar Rotation diminishes, but does not eliminate, Age Spreads
- The effects of stellar rotation along the main sequence of the 100 Myr old massive cluster NGC 1850
- New Clues to the Cause of Extended Main Sequence Turn-Offs in Intermediate-Age Star Clusters in the Magellanic Clouds
- In Search of Possible Associations between Planetary Nebulae and Open Clusters
- Unresolved Binaries in the Intermediate Mass Range in the Pleiades Star Cluster
- Astrometric star-cluster membership probability: application to the case of M 37 with Gaia EDR3
- Astro-photometric study of M37 with Gaia and wide-field ugi-imaging
- Signature of a chemical spread in the open cluster M37