Searching for globular cluster chemical anomalies on the main sequence of a young massive cluster

Abstract

The spectroscopic and photometric signals of the star-to-star abundance variations found in globular clusters seem to be correlated with global parameters like the cluster's metallicity, mass and age. Understanding this behaviour could bring us closer to the origin of these intriguing abundance spreads. In this work we use deep HST photometry to look for evidence of abundance variations in the main sequence of a young massive cluster NGC 419 ($\sim 10^5$ M${}_{\odot }$, $\sim 1.4$ Gyr). Unlike previous studies, here we focus on stars in the same mass range found in old globulars ($\sim 0.75-1$ M${}_{\odot }$), where light elements variations are detected. We find no evidence for N abundance variations among these stars in the $Un-B$ and $U-B$ CMD of NGC 419. This is at odds with the N-variations found in old globulars like 47 Tuc, NGC 6352 and NGC 6637 with similar metallicity to NGC 419. Although the signature of the abundance variations characteristic of old globulars appears to be significantly smaller or absent in this young cluster, we cannot conclude if this effect is mainly driven by its age or its mass.

9 pages, 8 figures, accepted for publication in MNRAS

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• On the Nitrogen variation in ~2 Gyr old massive star clusters in the Large Magellanic Cloud
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• Multiple stellar populations at less evolved stages: detection of chemical variations among main-sequence dwarfs in NGC 1978
• Multiple stellar populations at less evolved stages-II: no evidence of significant helium spread among NGC 1846 dwarfs
• On the Precision of Full-spectrum Fitting of Stellar Populations. III. Identifying Age Spreads
• Extended Main-Sequence Turnoff and Red Clump in intermediate-age star clusters: A study of NGC 419
• Chemical composition of the young massive cluster NGC 1569-B
• Extended Main Sequences in Star Clusters