Examinando por Autor "Dias B."

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    The VISCACHA survey - VI. Dimensional study of the structure of 82 star clusters in the Magellanic Clouds
    (Oxford University Press, 2023-03) Jimena Rodríguez M.; Feinstein C.; Baume G.; Dias B.; Maia F.S.M.; Santos J.F.C.; Kerber L.; Minniti D.; Pérez-Villegas A.; De Bórtoli B.; Parisi M.C.; Oliveira R.A.P.
    We present a study of the internal structure of 82 star clusters located at the outer regions of the Large Magellanic Cloud and the Small Magellanic Cloud using data of the VISCACHA Survey. Through the construction of the minimum spanning tree, which analyses the relative position of stars within a given cluster, it was possible to characterize the internal structure and explore the fractal or subclustered distribution for each cluster. We computed the parameters m (which is the average length of the connected segments normalized by the area), s (which is the mean points separation in units of cluster radius), and Q (the ratio of these components). These parameters are useful to distinguish between radial, homogeneous, and substructured distributions of stars. The dependence of these parameters with the different characteristics of the clusters, such as their ages and spatial distribution, was also studied. We found that most of the studied clusters present a homogeneous stellar distribution or a distribution with a radial concentration. Our results are consistent with the models, suggesting that more dynamically evolved clusters seem to have larger Q values, confirming previous results from numerical simulations. There also seems to be a correlation between the internal structure of the clusters and their galactocentric distances, in the sense that for both galaxies, the more distant clusters have larger Q values. We also paid particular attention to the effects of contamination by non-member field stars and its consequences finding that field star decontamination is crucial for these kinds of studies. © 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
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    Three new Galactic globular cluster candidates: FSR1700, Teutsch67, and CWNU4193
    (EDP Sciences, 2024-09) Saroon S.; Dias B.; Minniti D.; Parisi M.C.; Gómez M.; Alonso-García J.
    The VISTA Variables in the Via Láctea Extended Survey (VVVX) enables exploration of previously uncharted territories within the inner Milky Way (MW), particularly those obscured by stellar crowding and intense extinction. Our objective is to identify and investigate new star clusters to elucidate their intrinsic characteristics. Specifically, we are focused on uncovering new candidate globular clusters (GCs) situated at low Galactic latitudes, with the ultimate goal of completing the census of the MW GC system. Leveraging a combination of near-infrared (NIR) data from the VVVX survey and Two Micron All Sky Survey (2MASS), along with optical photometry and precise proper motions (PMs) from the Gaia Data Release 3 (DR3), we are conducting a systematic characterisation of new GCs. As a result, we report the discovery and characterisation of four new Galactic clusters named FSR 1700, FSR 1415, CWNU 4193, and Teutsch 67, all located within the MW disc. We estimate a wide range of reddening, with values ranging from 0.44 to 0.73 mag for E(J'''Ks). The heliocentric distances span from 10.3 to 13.2 kpc. Additionally, we determine their metallicities and ages, finding a range of '0.85 to '0.75 dex for [Fe/H] and ages approximately close to 11 Gyr, respectively. FSR 1415 is an exception; it is an old open cluster with an age of 3 Gyr and [Fe/H] of '0.10. Furthermore, we fitted the radial density profiles to derive their structural parameters like the tidal radius, core radius, and concentration parameters. In conclusion, based on their positions, kinematics, metallicities, and ages, and comparing our findings with existing literature, we categorise FSR 1700, Teutsch 67, and CWNU 4193 as genuine GC candidates, while FSR 1415 is an old open cluster exhibiting characteristics of a post-core-collapse cluster.