The chemical composition of the low-mass Galactic globular cluster NGC 6362

D. Massari , A. Mucciarelli , E. Dalessandro , M. Bellazzini , S. Cassisi , G. Fiorentino , R. A. Ibata (1) , C. Lardo , M. Salaris

1 ObAS - Observatoire astronomique de Strasbourg

We present chemical abundances for 17 elements in a sample of 11 red giant branch stars in NGC 6362 from UVES spectra. NGC 6362 is one of the least massive globulars where multiple populations have been detected, yet its detailed chemical composition has not been investigated so far. NGC 6362 turns out to be a metal-intermediate ([Fe/H] = -1.07 ± 0.01 dex) cluster, with its α-peak and Fe-peak elements content compatible with that observed in clusters with similar metallicity. It also displays an enhancement in its s-process element abundances. Among the light elements involved in the multiple populations phenomenon, only [Na/Fe] shows star-to-star variations, while [Al/Fe] and [Mg/Fe] do not show any evidence for abundance spreads. A differential comparison with M4, a globular cluster with similar mass and metallicity, reveals that the two clusters share the same chemical composition. This finding suggests that NGC 6362 is indeed a regular cluster, formed from gas that has experienced the same chemical enrichment of other clusters with similar metallicity.

Mots clés: techniques: spectroscopic; stars: abundances; globular clusters: individual: (NGC 6362); Astrophysics - Solar and Stellar Astrophysics; Astrophysics - Astrophysics of Galaxies

Domaines: Planète et Univers [physics]

D. Massari, A. Mucciarelli, E. Dalessandro, M. Bellazzini, S. Cassisi, et al.. The chemical composition of the low-mass Galactic globular cluster NGC 6362. Monthly Notices of the Royal Astronomical Society, 2017, 468, pp.1249-1258. ⟨10.1093/mnras/stx549⟩. ⟨insu-03707878⟩