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Libralato, M, Gerasimov, R, Bedin, L, Anderson, J, Apai, D, Bellini, A, Burgasser, AJ, Griggio, M, Nardiello, D, Salaris, M, Scalco, M and Vesperini, E (2024) JWST imaging of the closest globular clusters: IV. Chemistry, luminosity, and mass functions of the lowest-mass members in the NIRISS parallel fields. Astronomy & Astrophysics, 690. ISSN 0004-6361
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JWST imaging of the closest globular clusters IV Chemistry luminosity and mass functions of the lowest mass members.pdf - Published Version Available under License Creative Commons Attribution. Download (5MB) | Preview |
Abstract
We present observations of the two closest globular clusters, NGC 6121 and NGC 6397, taken with the NIRISS detector of JWST. The combination of our new JWST data with archival Hubble Space Telescope (HST) images allows us to compute proper motions, disentangle cluster members from field objects, and probe the main sequence (MS) of the clusters down to <0.1 M as well as the brighter part of the white-dwarf sequence. We show that theoretical isochrones fall short in modeling the low-mass MS and discuss possible explanations for the observed discrepancies. Our analysis suggests that the lowest-mass members of both clusters are significantly more metal-rich and oxygen-poor than their higher-mass counterparts. It is unclear whether the difference is caused by a genuine mass-dependent chemical heterogeneity, low-Temperature atmospheric processes altering the observed abundances, or systematic shortcomings in the models. We computed the present-day local luminosity and mass functions of the two clusters; our data reveal a strong flattening of the mass function indicative of a significant preferential loss of low-mass stars in agreement with previous dynamical models for these two clusters. We have made our NIRISS astro-photometric catalogs and stacked images publicly available to the community.
| Item Type: | Article |
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| Uncontrolled Keywords: | 0201 Astronomical and Space Sciences; Astronomy & Astrophysics |
| Subjects: | Q Science > QB Astronomy Q Science > QC Physics |
| Divisions: | Astrophysics Research Institute |
| Publisher: | EDP Sciences |
| SWORD Depositor: | A Symplectic |
| Date Deposited: | 28 Nov 2024 10:19 |
| Last Modified: | 28 Nov 2024 10:30 |
| DOI or ID number: | 10.1051/0004-6361/202451295 |
| URI: | https://researchonline.ljmu.ac.uk/id/eprint/24903 |
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