Space Velocities of Southern Globular Clusters. V. A Low Galactic Latitude Sample

Casetti-Dinescu, Dana I.; Girard, Terrence M.; Herrera, David; Altena, W. F. van; López, Carlos; Castillo, Danilo J.

doi:10.1086/518507

Cited by 85 publications

(132 citation statements)

References 64 publications

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“…Unfortunately, there are no estimates of the M I for NGC 2808 in the literature. However, the orbit of this GC suggests that its PS was much more massive than the present-day GC, owing to interaction with the Milky Way (Casetti- Dinescu et al 2007).…”

Section: The Case Of Ngc 2808mentioning

confidence: 95%

Formation of multiple populations in globular clusters: another possible scenario

Valcarce

Catelan

2011

A&A

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Aims. While spreads in chemical composition are now believed to be a universal characteristic of globular clusters (GCs), not all of them display evidence of multiple populations in their color-magnitude diagrams (CMDs). Here we present a new scenario for the formation of GCs, in an attempt to qualitatively explain these otherwise elusive observational results. Methods. Our scenario divides GCs into three groups, depending on the initial mass (M I ) of the progenitor structure (PS), as follows: i) massive PSs can retain the gas ejected by massive stars, including the ejecta of core-collapse SNe. ii) Intermediate-mass PSs can retain at least a fraction of the fast winds of massive stars, but none of the core-collapse SNe ejecta. iii) Low-mass PSs can only retain the slow winds of intermediate-mass stars. The first group would contain members such as ω Centauri (NGC 5139), M 54 (NGC 6715), M 22 (NGC 6656), and Terzan 5, whereas NGC 2808 (and possibly NGC 2419) would be members of the second group. The remaining GCs that have only a spread in light elements, such as O and Na, would be members of the third group. Results. According to our scenario, the different components of ω Cen should not have a sizeable spread in age. We argue that this is consistent with the available observations. We present other simple arguments in favor of our scenario, which can be described in terms of two main analytical relations: i) one between the actual observed ratio of the number of first to second generation stars (R FG SG ) and the fraction of first generation stars that have been lost by the GC (S L ) and ii) another between S L and M I . We also suggest a series of future improvements to and empirical tests of the modeling that may help decide whether the proposed scenario properly describes the chemical evolution of GCs.

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Section: The Case Of Ngc 2808mentioning

confidence: 95%

Formation of multiple populations in globular clusters: another possible scenario

Valcarce

Catelan

2011

A&A

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“…Briefly, using the Harris (1996) catalogue, we first classified as outer halo GCs the ones currently located at distances greater than 15 kpc (Carollo et al 2008) from the Galactic centre, and clusters with Galactocentric distance less than 3.5 kpc were instead considered as bulge GCs. To separate the inner halo clusters from the disk ones, we used the rotational velocity around the Galactic centre by Dinescu et al (1999) and Casetti-Dinescu et al (2007) whenever possible. When this information was not available, we used the differences between the observed radial velocity (corrected to the LSR) and the one expected from the Galactic rotation curve (see Clemens 1985).…”

Section: The Galactic Gc Samplementioning

confidence: 99%

Properties of stellar generations in globular clusters and relations with global parameters

Carretta¹,

Bragaglia²,

Gratton

et al. 2010

A&A

478

712

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We revise the scenario of the formation of Galactic globular clusters (GCs) by adding the observed detailed chemical composition of their different stellar generations to the set of their global parameters. We exploit the unprecedented set of homogeneous abundances of more than 1200 red giants in 19 clusters, as well as additional data from literature, to give a new definition of bona fide GCs, as the stellar aggregates showing the Na-O anticorrelation. We propose a classification of GCs according to their kinematics and location in the Galaxy in three populations: disk/bulge, inner halo, and outer halo. We find that the luminosity function of GCs is fairly independent of their population, suggesting that it is imprinted by the formation mechanism only marginally affected by the ensuing evolution. We show that a large fraction of the primordial population should have been lost by the proto-GCs. The extremely low Al abundances found for the primordial population of massive GCs indicate a very fast enrichment process before the formation of the primordial population. We suggest a scenario for the formation of GCs that includes at least three main phases: i) the formation of a precursor population (likely due to the interaction of cosmological structures similar to those that led to the formation of dwarf spheroidals, but residing at smaller Galactocentric distances, with the early Galaxy or with other structures); ii) the triggering of a long episode of star formation (the primordial population) from the precursor population; and iii) the formation of the current GC, mainly within a cooling flow formed by the slow winds of a fraction of the primordial population. The precursor population is very effective in raising the metal content in massive and/or metal-poor (mainly halo) clusters, while its rôle is minor in small and/or metal-rich (mainly disk) ones. Finally, we use principal component analysis and multivariate relations to study the phase of metal enrichment from first to second generation. We conclude that most of the chemical signatures of GCs may be ascribed to a few parameters, the most important being metallicity, mass, and cluster age. Location within the Galaxy (as described by the kinematics) also plays some rôle, while additional parameters are required to describe their dynamical status.

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“…Criteria using the space velocity V, as proposed by Dinescu, Girard, & van Altena (1997), Dinescu, van Altena, & Girard (1999a), Dinescu, Girard, & van Altena (1999b), Dinescu et al (2003), and Casetti- Dinescu et al (2007Dinescu et al ( , 2010Dinescu et al ( , 2013, are only feasible if proper motions are available, besides radial velocities. In particular, Dinescu et al (2003) verified the classification of clusters as members of different galaxy components in terms of kinematics.…”

Section: The Sample Of Bulge Globular Clustersmentioning

confidence: 99%

Globular Clusters in the Galactic Bulge

Bica

Ortolani

Barbuy

2016

Publ. Astron. Soc. Aust.

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A view of the Galactic bulge by means of their globular clusters is fundamental for a deep understanding of its formation and evolution. Connections between the globular cluster and field star properties in terms of kinematics, orbits, chemical abundances, and ages should shed light on different stellar population components. Based on spatial distribution and metallicity, we define a probable best list of bulge clusters, containing 43 entries. Future work on newly discovered objects, mostly from the VVV survey, is suggested. These candidates might alleviate the issue of missing clusters on the far side of the bulge. We discuss the reddening law affecting the cluster distances towards the centre of the Galaxy, and conclude that the most suitable total-to-selective absorption value appears to be R V =3.2, in agreement with recent analyses. An update of elemental abundances for bulge clusters is provided.

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Space Velocities of Southern Globular Clusters. V. A Low Galactic Latitude Sample

Cited by 85 publications

References 64 publications

Formation of multiple populations in globular clusters: another possible scenario

Formation of multiple populations in globular clusters: another possible scenario

Properties of stellar generations in globular clusters and relations with global parameters

Globular Clusters in the Galactic Bulge

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