Examinando por Autor "Garro, E.R."

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    A new low-luminosity globular cluster discovered in the Milky Way with the VVVX survey
    (EDP Sciences, 2022-06) Garro, E.R.; Minniti, D.; Gómez, M.; Fernández-Trincado, J.G.; Alonso-García, J.; Hempel, M.; Zelada Bacigalupo, R.
    Context. The VISTA Variables in the Via Láctea Extended Survey (VVVX) allows us to probe previously unexplored regions of the inner Milky Way (MW), especially those that are affected by stellar crowding and strong extinction. Aims. Our long-term goal is to identify new star clusters and investigate them to reveal their true nature. In particular, we are looking for new candidate globular clusters (GCs) located in the Galactic bulge and disk, with the aim of completing the census of theMWGC system. Methods. We searched and characterised new GCs, using a combination of the near-infrared (IR) VVVX survey and Two Micron All Sky survey (2MASS) datasets, and the optical Gaia Early Data Release 3 (EDR3) photometry and its precise proper motions (PMs). Results. We report the discovery of a new Galactic GC, named Garro 02, situated at RA= 18:05:51.1, Dec = 17:42:02 and l = 12:°042, b = +1:°656. Performing a PM-decontamination procedure, we built a final catalogue with all cluster members, on which we performed a photometric analysis.We calculated a reddening of E(J Ks) = 1:07±0:06 mag and extinction of AKs = 0:79±0:04 mag in the near-IR; while E(BP RP) = 2:40 ± 0:01 mag and AG = 4:80 ± 0:02 mag in optical passbands. Its heliocentric distance is D = 5:6±0:8 kpc, which places Garro 02 at a Galactocentric distance of RG = 2:9 kpc and Z = 0:006 kpc above the Galactic plane.We also estimated the metallicity and age by comparison with known GCs and by fitting PARSEC isochrones, finding [Fe/H] = 1:30±0:2 dex and age = 12 ± 2 Gyr. We derived the mean cluster PM of (μα ff; μ°) = (6:07 ± 0:62; 6:15 ± 0:75) mas yr1. We calculated the cluster luminosity in the near-IR of MKs = 7:52±1:23 mag, which is equivalent to MV = 5:44 mag. The core and tidal radii from the radial density profile are rc = 1:25 ± 0:27 arcmin (2.07 pc) and rt = 7:13 ± 3:83 arcmin (11.82 pc), respectively. Conclusions. We confirm Garro 02 as a new genuine Galactic GC, located in the MW bulge. It is a low-luminosity, metal-poor, and old GC, and it is a lucky survivor of the strong dynamical processes that occurred during the MW’s entire life. © E. R. Garro et al. 2022.
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    Unveiling the nature of 12 new low-luminosity Galactic globular cluster candidates
    (EDP Sciences, 2022-03-01) Garro, E.R.; Minniti, D.; Alessi, B.; Patchick, D.; Kronberger, M.; Alonso-García, J.; Fernández-Trincado, J.G.; Gómez, M.; Hempel, M.; Pullen, J.B.; Saito, R.K.; Ripepi, V.; Zelada Bacigalupo, R.
    Context. The Galactic globular cluster system is incompletely known, especially in the low-latitude regions of the Galactic bulge and disk. We report the physical characterisation of 12 star clusters in the Milky Way, most of which are explored here for the first time. Aims. Our primary aim is determining their main physical parameters, such as reddening, extinction, metallicity, age, total luminosity, mean cluster proper motions (PMs), and distances, in order to reveal the physical nature of these clusters. Methods. We study the clusters using optical and near-infrared (NIR) datasets. In particular, we use the Gaia Early Data Release 3 (EDR3) PMs in order to perform a PM decontamination procedure and build final catalogues with probable members. We match the Gaia EDR3 with the VISTA Variables in the Vía Láctea extended (VVVX) survey and the Two Micron All-Sky survey (2MASS) in the NIR, in order to construct complete NIR and optical colour-magnitude diagrams (CMDs) and investigate the clusters properties. Results. The extinctions are evaluated using existing reddening maps. We find ranges spanning 0:09. AKs. 0:86 mag and 0:89. AG. 4:72 mag in the NIR and optical, respectively. Adopting standard intrinsic red clump (RC) magnitudes and extinction values, we first obtain the distance modulus for each cluster and thereafter their heliocentric distances, which range from about 4 to 20 kpc. Therefore, we are able to place these clusters at 3. RG. 14 kpc from the Galactic centre. The best PARSEC isochrone fit yields a metallicity range of-1:8 < [Fe/H] < +0:3 and an approximate age range of 2 < age < 14 Gyr. Finally, we find that all clusters have low luminosities, with-6:9 < MV <-3:5 mag. Conclusions. Based on our photometric analysis, we find both open clusters (OCs) and globular clusters (GCs) in our sample. In particular, we confirm the OC nature for Kronberger 100, while we classify Patchick 125 as a metal-poor GC, Ferrero 54 as a metalrich GC, and ESO 92-18 as a possible old OC or young GC. The classification as GC candidates is also suggested for Kronberger 99, Patchick 122, Patchick 126, Riddle 15, FSR 190, and Gaia 2. We also conclude that Kronberger 119 and Kronberger 143 might be either old OCs or young GCs. © ESO 2022.
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    VVVX-Gaia discovery of a low luminosity globular cluster in the Milky Way disk
    (EDP Sciences, 2020-10) Garro, E.R.; Minniti, D.; Gómez, M.; Alonso-García, J.; Barbá, R.H.; Barbuy, B.; Clariá, J.J.; Chené, A.N.; Dias, B.; Hempel, M.; Ivanov, V.D.; Lucas, P.W.
    Context. Milky Way globular clusters (GCs) are difficult to identify at low Galactic latitudes because of high differential extinction and heavy star crowding. The new deep near-infrared (IR) images and photometry from the VISTA Variables in the Via Láctea Extended Survey (VVVX) allow us to chart previously unexplored regions. Aims. Our long term aim is to complete the census of Milky Way GCs. The immediate goals are to estimate the astrophysical parameters for the newly discovered GC candidates, measuring their reddenings, extinctions, distances, total luminosities, proper motions, sizes, metallicities, and ages. Methods. We used the near-IR VVVX survey database, in combination with the optical photometry and proper motions (PMs) from Gaia Data Release 2 (DR2), and with the Two Micron All Sky Survey photometry to search for and characterise new GCs within the southern Galactic plane (|b| < 5°). Results. We report the detection of a heretofore unknown Galactic GC at RA = 14:09:00.0; Dec =-65:37:12 (J2000) corresponding to l = 310.828 deg; and b =-3.944 deg in galactic coordinates. We calculate a reddening of E(J-Ks) = (0.3 ± 0.03) mag and an extinction of AKs = (0.15 ± 0.01) mag for this new GC. Its distance modulus and corresponding distance were measured as (m-M) = (15.93 ± 0.03) mag and D = (15.5 ± 1.0) kpc, respectively. We also estimate the metallicity and age by comparison with known GCs and by fitting PARSEC and Dartmouth isochrones, finding [Fe/H] = (-0.70 ± 0.2) dex and t = (11.0 ± 1.0) Gyr. The mean GC PMs from Gaia DR2 are μα∗ = (-4.68 ± 0.47) mas yr-1 and μδ = (-1.34 ± 0.45) mas yr-1. The total luminosity of our cluster is estimated to be MKs = (-7.76 ± 0.5) mag. The core and tidal radii from the radial density profile are rc ∼ 2.1′ (4.6 pc) and rt = 6.5′ (14.6 pc) at the cluster distance. Conclusions. We have found a new low luminosity, old and metal-rich GC, situated in the far side of the Galactic disk at RG = 11.2 kpc from the Galactic centre and at z = 1.0 kpc below the plane. Interestingly, the location, metallicity, and age of this GC are coincident with the Monoceros ring structure. © 2020 ESO.