VVV CL001: Likely the Most Metal-poor Surviving Globular Cluster in the Inner Galaxy

Fernández-Trincado, J. G.; Minniti, D.; Souza, Stefano O.; Beers, Timothy C.; Geisler, Doug; Bidin, C. Moni; Villanova, S.; Majewski, Steven R.; Barbuy, B.; Pérez-Villegas, Ángeles; Henao, Lady; Romero-Colmenares, María; Román-Lópes, A.; Lane, Richard R.

doi:10.3847/2041-8213/abdf47

Cited by 33 publications

(14 citation statements)

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“…The best way to overcome these problems is to use near-infrared (NIR) observations, given that red giant stars have their emission peak in the NIR and the interstellar dust becomes almost transparent at these wavelengths. The identification of new candidates and their subsequent confirmation as real GCs can be facilitated at these spectral regions (for instance UKS 1 and VVV-CL001; Fernández-Trincado et al 2020 andFernández-Trincado et al 2021, just to mention a few). A step forwards has been possible thanks to the VISTA Variables in the Via Láctea (VVV) survey and its eXtension (VVVX).…”

Section: Introductionmentioning

confidence: 99%

Inspection of 19 globular cluster candidates in the Galactic bulge with the VVV survey

Garro

Minniti

Gómez

et al. 2022

A&A

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Context. The census of the globular clusters (GCs) in the Milky Way (MW) is still a work in progress. The advent of new deep surveys has made it possible to discover many new star clusters both in the Galactic disk and bulge, but many of these new candidates have not yet been studied in detail, leaving a veil on their true physical nature. Aims. We explore the nature of 19 new GC candidates in the Galactic bulge by analysing their colour-magnitude diagrams (CMDs) in the near-infrared (NIR) using the VISTA Variables in the Via Láctea Survey (VVV) database. We estimate their main astrophysical parameters: reddening and extinction, distance, total luminosity, mean cluster proper motions (PMs), metallicity, and age. Methods. We obtain the cluster catalogues including the likely cluster members by applying a decontamination procedure on the observed CMDs based on the vector PM diagrams from VIRAC2. We adopt NIR reddening maps in order to calculate the reddening and extinction for each cluster, and then estimate the distance moduli and heliocentric distances. Metallicities and ages are evaluated by fitting theoretical stellar isochrones. We also calculate their luminosities in comparison with known Galactic GCs. Results. We estimate a wide reddening range of 0.25 E(J − K s ) 2.0 mag and extinction 0.11 A K s 0.86 mag for the sample clusters, as expected in the bulge regions. The range of heliocentric distances is 6.8 D 11.4 kpc. This allows us to place these clusters between 0.56 and 3.25 kpc from the Galactic centre, assuming R = 8.2 kpc. Also, their PMs are kinematically similar to the typical motion of the Galactic bulge, apart from VVV-CL160, which shows different PMs. We also derive their metallicities and ages, finding −1.40 [Fe/H] 0.0 dex and t ≈ 8 − 13 Gyr respectively. The luminosities are calculated both in K s − and V−bands, recovering −3.4 M V −7.5. We also examine the possible RR Lyrae members found in the cluster fields. Conclusions. Based on their positions, kinematics, metallicities, and ages, and comparing our results with the literature, we conclude that nine candidates are real GCs, seven need more observations to be fully confirmed as GCs, and three candidates are discarded as GCs and appear to be younger open clusters.

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Section: Introductionmentioning

confidence: 99%

Inspection of 19 globular cluster candidates in the Galactic bulge with the VVV survey

Garro

Minniti

Gómez

et al. 2022

A&A

Self Cite

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“…The combination of optical and near-infrared surveys, such as the Two-Micron All Sky Survey (2MASS; Skrutskie et al 2006), VISTA Variables in the Vía Láctea (VVV; Minniti et al 2010;Saito et al 2012) and its extension (VVVX; Minniti 2018), the ESA Gaia mission (Gaia Collaboration et al 2016, 2018 with its unprecedented astrometric precision, and the second generation of the Apache Point Observatory Galactic Evolution Experiment survey (APOGEE-2; Majewski et al 2017), which provides accurate spectroscopic and kinematics information, has allowed the extraordinary power of these ancient systems to be fully exploited, even in densely populated regions and those heavily obscured by the interstellar medium (ISM). E-mail: jose.fernandez@ucn.cl and/or jfernandezt87@gmail.com Such is the case of VVV CL001 with E(B−V)∼ 2.2, which was recently re-classified as the most metal-poor GC found so far -with [Fe/H]∼ −2.45to have survived near the bulge region (Fernández-Trincado et al 2021d), and NGC 6330 (or Tonantzintla 1) a highly reddened, E(B−V)∼1.07 bulge GC, recently identified as the first known case of a relatively high-metallicity GC exhibiting evidence of correlation between its light-and heavy-elements and the presence of the phenomenon of multiple stellar populations (Fernández-Trincado et al 2021a). In addition, UKS 1, a heavily reddened GC, with E(B−V)∼2.62, was recently classified as a fossil relic of the bulge based on its chemodynamics properties (Fernández-Trincado et al 2020).…”

Section: Introductionmentioning

confidence: 99%

APOGEE-2S view of the globular cluster Patchick 125 (Gran 3). New metallicity and elemental abundances from high-resolution spectroscopy

Fernández-Trincado,

Minniti,

Garro

et al. 2021

Preprint

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We present detailed elemental abundances, radial velocity, and orbital elements for Patchick 125, a recently discovered metal-poor globular cluster (GC) in the direction of the Galactic bulge. Near-infrared high-resolution (R ∼ 22, 500) spectra of two members were obtained during the second phase of the Apache Point Observatory Galactic Evolution Experiment at Las Campanas Observatory as part of the sixteenth Data Release (DR 16) of the Sloan Digital Sky Survey. We investigated elemental abundances for four chemical species, including α-(Mg, Si), Fe-peak (Fe), and odd-Z (Al) elements. We find a metallicity covering the range from [Fe/H] = −1.69 to −1.72, suggesting that Patchick 125 likely exhibits a mean metallicity [Fe/H] ∼ −1.7, which represents a significant increase in metallicity for this cluster compared to previous low-resolution spectroscopic analyses. We also found a mean radial velocity of 95.9 km s −1 , which is ∼21.6 km s −1 higher than reported in the literature. The observed stars exhibit an α-enrichment ([Mg/Fe] +0.20, and [Si/Fe] +0.30) that follows the typical trend of metal-poor GCs. The aluminum abundance ratios for the present two member stars are enhanced in [Al/Fe] +0.58, which is a typical enrichment characteristic of the so-called 'second-generation' of stars in GCs at similar metallicity. This supports the possible presence of the multiple-population phenomenon in Patchick 125, as well as its genuine GC nature. Further, Patchick 125 shows a low-energy, low-eccentric (< 0.4) and retrograde orbit captured by the inner Galaxy, near the edge of the bulge. We confirm that Patchick 125 is a genuine metal-poor GC, which is currently trapped in the vicinity of the Milky Way bulge.

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“…The symbols indicating progenitors shown in this table are as in Table 4; the new symbol K stands for the dwarf galaxy accretion event (Forbes 2020). In the old, metal-deficient, cluster VVV CL001, not listed by Massari et al (2019) and Forbes (2020), a possible association with Sequoia or Gaia-Enceladus structures has been suggested by Fernández-Trincado et al (2021a), and this is listed in Table 5. Fig.…”

Section: Mean Variationsmentioning

confidence: 99%

Orbits of globular clusters computed with dynamical friction in the Galactic anisotropic velocity dispersion field

Moreno,

Fernández-Trincado,

Pérez-Villegas

et al. 2021

Preprint

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We present a preliminary analysis of the effect of dynamical friction on the orbits of part of the globular clusters in our Galaxy. Our study considers an anisotropic velocity dispersion field approximated using the results of studies in the literature. An axisymmetric Galactic model with mass components consisting of a disc, a bulge, and a dark halo is employed in the computations. We provide a method to compute the dynamical friction acceleration in ellipsoidal, oblate, and prolate velocity distribution functions with similar density in velocity space. Orbital properties, such as mean time-variations of perigalactic and apogalactic distances, energy, and z-component of angular momentum, are obtained for globular clusters lying in the Galactic region 10 kpc, | | 5 kpc, with , cylindrical coordinates. These include clusters in prograde and retrograde orbital motion. Several clusters are strongly affected by dynamical friction, in particular Liller 1, Terzan 4, Terzan 5, NGC 6440, and NGC 6553, which lie in the Galactic inner region. We comment on the more relevant implications of our results on the dynamics of Galactic globular clusters, such as their possible misclassification between the categories 'halo', 'bulge', and 'thick disc', the resulting biasing of globular-cluster samples, the possible incorrect association of the globulars with their parent dwarf galaxies for accretion events, and the possible formation of 'nuclear star clusters'.

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VVV CL001: Likely the Most Metal-poor Surviving Globular Cluster in the Inner Galaxy

Cited by 33 publications

References 50 publications

Inspection of 19 globular cluster candidates in the Galactic bulge with the VVV survey

Inspection of 19 globular cluster candidates in the Galactic bulge with the VVV survey

APOGEE-2S view of the globular cluster Patchick 125 (Gran 3). New metallicity and elemental abundances from high-resolution spectroscopy

Orbits of globular clusters computed with dynamical friction in the Galactic anisotropic velocity dispersion field

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