NGC 362: another globular cluster with a split red giant branch

Carretta, E.; Bragaglia, A.; Gratton, R.; Lucatello, S.; D’Orazi, V.; Bellazzini, M.; Catanzaro, G.; Leone, F.; Momany, Y.; Sollima, A.

doi:10.1051/0004-6361/201321905

Cited by 73 publications

(98 citation statements)

References 72 publications

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“…Wheeler et al 1989). This pattern is also Carretta et al (2009aCarretta et al ( ,b, 2010bCarretta et al ( ,c, 2011Carretta et al ( , 2013Carretta et al ( , 2014bCarretta et al ( , 2015, and asterisks are stars in NGC 2808 from . In each panel the error bars represent internal errors.…”

Section: Elements Up To Iron Peaksupporting

confidence: 59%

Chemical characterisation of the globular cluster NGC 5634 associated to the Sagittarius dwarf spheroidal galaxy

Carretta

Bragaglia

Lucatello

et al. 2017

A&A

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As part of our on-going project on the homogeneous chemical characterisation of multiple stellar populations in globular clusters (GCs), we studied NGC 5634, associated to the Sagittarius dwarf spheroidal galaxy, using high-resolution spectroscopy of red giant stars collected with VLT/FLAMES. We present here the radial velocity distribution of the 45 observed stars, 43 of which are cluster members, the detailed chemical abundance of 22 species for the seven stars observed with UVES-FLAMES, and the abundance of six elements for stars observed with GIRAFFE. On our homogeneous UVES metallicity scale, we derived a low-metallicity [Fe/H] = −1.867 ± 0.019 ± 0.065 dex (±statistical ±systematic error) with σ = 0.050 dex (7 stars). We found the normal anticorrelations between light elements (Na and O, Mg and Al), a signature of multiple populations typical of massive and old GCs. We confirm the associations of NGC 5634 to the Sgr dSph, from which the cluster was lost a few Gyr ago, on the basis of its velocity and position, and the abundance ratios of α and neutron capture elements.

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Section: Elements Up To Iron Peaksupporting

confidence: 59%

Chemical characterisation of the globular cluster NGC 5634 associated to the Sagittarius dwarf spheroidal galaxy

Carretta

Bragaglia

Lucatello

et al. 2017

A&A

Self Cite

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“…As predicted by Carretta et al (2009cCarretta et al ( , 2010bCarretta et al ( , 2011bCarretta et al ( , 2013Carretta et al ( , 2014b Salaris et al (2006), the luminosity of the RGB bump is sensitive to the He abundance (the bump is brighter for a population where a He-enhanced component is present). This prediction has been long since observationally confirmed both with spectroscopy (using the component with Na enhancement in GCs as a proxy, see Carretta et al 2007a;Bragaglia et al 2010) and with photometry (e.g.…”

Section: Multiple Stellar Populations In M 80mentioning

confidence: 73%

“…To avoid the ensuing trends as a function of the v t , whose values are derived from a plaethora of weaker Fe lines, we adopted the procedure followed in Carretta et al (2013Carretta et al ( , 2014a. Abundances of Ba were obtained using a common [Fe/H] for all stars (equal to the mean The abundances of Ba are not correlated with any of the protoncapture elements.…”

Section: Neutron-capture Elementsmentioning

confidence: 99%

The normal chemistry of multiple stellar populations in the dense globular cluster NGC 6093 (M 80)

Carretta

Bragaglia

Gratton

et al. 2015

A&A

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We present the abundance analysis of 82 red giant branch stars in the dense, metal-poor globular cluster NGC 6093 (M 80), the largest sample of stars analysed in this way for this cluster. From high-resolution UVES spectra of 14 stars and intermediate resolution GIRAFFE spectra for the other stars we derived abundances of O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Ba, La, Ce, Pr, Nd, Sm, Eu. On our UVES metallicity scale the mean metal abundance of M 80 is [Fe/H] = −1.791 ± 0.006 ± 0.076 (±statistical ±systematic error) with σ = 0.023 (14 stars). M 80 shows star-to-star variations in proton-capture elements, and the extension of the Na-O anti-correlation perfectly fit the relations with (i) total cluster mass; (ii) horizontal branch morphology; and (iii) cluster concentration previously found by our group. The chemistry of multiple stellar populations in M 80 does not look extreme. The cluster is also a representative of halo globular clusters concerning the pattern of α-capture and Fe-group elements. However we found that a significant contribution from the s-process is required to account for the distribution of neutron-capture elements. A minority of stars in M 80 seem to exhibit slightly enhanced abundances of s-process species, compatible with those observed in M 22 and NGC 1851, although further confirmation from larger samples is required.

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“…A key observation is that elemental enrichment in GCs seems to be discrete (Marino et al 2011;Carretta et al 2012Carretta et al , 2014Renzini et al 2015). Discreteness requires burst-like contamination, and in the stellar interaction model here, that means intermittent events of catastrophic massive-star interactions.…”

Section: Introductionmentioning

confidence: 93%

Globular Cluster Formation at High Density: A Model for Elemental Enrichment with Fast Recycling of Massive-star Debris

Elmegreen

2017

ApJ

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The self-enrichment of massive star clusters by p-processed elements is shown to increase significantly with increasing gas density as a result of enhanced star formation rates and stellar scatterings compared to the lifetime of a massive star. Considering the type of cloud core where a globular cluster might have formed, we follow the evolution and enrichment of the gas and the time dependence of stellar mass. A key assumption is that interactions between massive stars are important at high density, including interactions between massive stars and massive star binaries that can shred stellar envelopes. Massive-star interactions should also scatter low-mass stars out of the cluster. Reasonable agreement with the observations is obtained for a cloud core mass of ∼ 4 × 10 6 M ⊙ and a density of ∼ 2 × 10 6 cm −3 . The results depend primarily on a few dimensionless parameters, including, most importantly, the ratio of the gas consumption time to the lifetime of a massive star, which has to be low, ∼ 10%, and the efficiency of scattering low-mass stars per unit dynamical time, which has to be relatively large, such as a few percent. Also for these conditions, the velocity dispersions of embedded globular clusters should be comparable to the high gas dispersions of galaxies at that time, so that stellar ejection by multi-star interactions could cause low-mass stars to leave a dwarf galaxy host altogether. This could solve the problem of missing first-generation stars in the halos of Fornax and WLM.

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NGC 362: another globular cluster with a split red giant branch

Cited by 73 publications

References 72 publications

Chemical characterisation of the globular cluster NGC 5634 associated to the Sagittarius dwarf spheroidal galaxy

Chemical characterisation of the globular cluster NGC 5634 associated to the Sagittarius dwarf spheroidal galaxy

The normal chemistry of multiple stellar populations in the dense globular cluster NGC 6093 (M 80)

Globular Cluster Formation at High Density: A Model for Elemental Enrichment with Fast Recycling of Massive-star Debris

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