Examinando por Autor "Zelada Bacigalupo, R."
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Ítem A deep near-infrared view of the Ophiuchus galaxy cluster(EDP Sciences, 2022-07) Galdeano, D.; Coldwell, G.; Duplancic, F.; Alonso, S.; Pereyra, L.; Minniti, D.; Zelada Bacigalupo, R.; Valotto, C.; Baravalle, L.; Alonso, M.V.; Nilo Castellón, J.L.Context. The Ophiuchus cluster of galaxies, located at low latitudes in the direction of the Galactic bulge, has been relatively poorly studied in comparison with other rich galaxy clusters, such as Coma, Virgo, and Fornax, despite being the second brightest X-ray cluster in the sky. Aims. Our aim is perform a study of the hidden galaxy population of the massive cluster Ophiuchus located in the Zone of Avoidance. Methods. Deep near-infrared images and photometry from the VISTA Variables in the Vía Láctea eXtended (VVVX) survey were used to detect galaxy member candidates of the Ophiuchus cluster up to 2 Mpc from the cD galaxy 2MASX J17122774-2322108 using criteria from a past paper to select the galaxies among the foreground sources. We also perform a morphological visual classification and generate color-magnitude diagrams and density profiles. Results. We identify 537 candidate galaxy members of the Ophiuchus cluster up to 2 Mpc from the cD galaxy, increasing by a factor of seven the number of reported Ophiuchus galaxies. In addition, we performed a morphological classification of these galaxy candidates finding that the fraction of ellipticals reaches more than 60% in the central region of the cluster. On the other hand, the fraction of spirals fraction is lower than 20%, remaining almost constant throughout the cluster. Moreover, we study the red sequence of galaxy member candidates and use mock catalogs to explore the density profile of the cluster, finding that the value derived from the mock catalog toward an overdense region is in agreement with the galaxy excess of the central zone of the Ophiuchus cluster. Conclusions. Our investigation of the hidden population of Ophiuchus galaxies underscores the importance of this cluster as a prime target for future photometric and spectroscopic studies. Moreover the results of this work highlight the potential of the VVVX survey to study extragalactic objects in the Zone of Avoidance. © 2022 D. Galdeano et al.Ítem 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.Ítem 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.