Browsing by Author "Carballo-Bello, Julio A."

Now showing 1 - 8 of 8
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    Extra-tidal structures around the Gaia Sausage candidate globular cluster NGC6779 (M56)
    (2019) Piatti, Andres E.; Carballo-Bello, Julio A.
    We present results on the stellar density radial profile of the outer regions of NGC6779, a Milky Way globular cluster recently proposed as a candidate member of the Gaia Sausage structure, a merger remnant of a massive dwarf galaxy with the Milky Way. Taking advantage of the Pan-STARRS PS1 public astrometric and photometric catalogue, we built the radial profile for the outermost cluster regions using horizontal branch and main-sequence stars, separately, in order to probe for different profile trends because of difference stellar masses. Owing to its relatively close location to the Galactic plane, we have carefully treated the chosen colour-magnitude regions properly correcting them by the amount of interstellar extinction measured along the line of side of each star, as well as cleaned them from the variable field star contamination observed across the cluster field. In the region spanning from the tidal to the Jacobi radii, the resulting radial profiles show a diffuse extended halo with an average power-law slope of -1. While analysing the relationships between the Galactocentric distance, the half-mass density, the half-light radius, the slope of the radial profile of the outermost regions, the internal dynamical evolutionary stage, among others, we found that NGC6779 shows structural properties similar to those of the remaining Gaia Sausage candidate globular clusters, namely, they are massive clusters (>10(5) M-circle dot) in a moderately early dynamical evolutionary stage, with observed extra-tidal structures.
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    Mirach's Goblin: Discovery of a dwarf spheroidal galaxy behind the Andromeda galaxy
    (2018) Martinez-Delgado, David; Grebel, Eva K.; Javanmardi, Behnam; Boschin, Walter; Longeard, Nicolas; Carballo-Bello, Julio A.; Makarov, Dmitry; Beasley, Michael A.; Donatiello, Giuseppe; Haynes, Martha P.; Forbes, Duncan A.; Romanowsky, Aaron J.
    Context. It is of broad interest for galaxy formation theory to carry out a full inventory of the numbers and properties of dwarf galaxies, both satellite and isolated, in the Local Volume.
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    Nature of a shell of young stars in the outskirts of the Small Magellanic Cloud
    (2019) Martinez-Delgado, David; Katherina Vivas, Anna; Grebel, Eva K.; Gallart, Carme; Pieres, Adriano; Bell, Cameron P. M.; Zivick, Paul; Lemasle, Bertrand; Johnson, Lent Clifton; Carballo-Bello, Julio A.; Noel, Noelia E. D.; Cioni, Maria-Rosa L.; Choi, Yumi; Besla, Gurtina; Schmidt, Judy; Zaritsky, Dennis; Gruendl, Robert A.; Seibert, Mark; Nidever, David; Monteagudo, Laura; Monelli, Mateo; Hubl, Bernhard; van der Marel, Roeland; Ballesteros, Fernando J.; Stringfellow, Guy; Walker, Alistair; Blum, Robert; Bell, Eric F.; Conn, Blair C.; Olsen, Knut; Martin, Nicolas; Chu, You-Hua; Inno, Laura; Boer, Thomas J. L.; Kallivayalil, Nitya; De Leo, Michele; Beletsky, Yuri; Neyer, Fabian; Munoz, Ricardo R.
    Context. Understanding the evolutionary history of the Magellanic Clouds requires an in-depth exploration and characterization of the stellar content in their outer regions, which ultimately are key to tracing the epochs and nature of past interactions.
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    Signatures of tidal disruption in the Milky Way globular cluster NGC 6981 (M72)
    (2021) Piatti, Andres E.; Mestre, Martin F.; Carballo-Bello, Julio A.; Carpintero, Daniel D.; Navarrete, Camila; Mora, Marcelo D.; Cenzano, Carolina
    We study the outer regions of the Milky Way globular cluster NGC 6981 based on publicly available BV photometry and new Dark Energy Camera (DECam) observations, both of which reach nearly 4 mag below the cluster main sequence (MS) turnoff. While the BV data sets reveal the present of extra-tidal features around the cluster, the much larger field of view of the DECam observations allowed us to identify some other tidal features, which extend from the cluster toward the opposite direction to the Milky Way center. Such structural features of clusters arise from stellar density maps built using MS stars, following a cleaning of the cluster color-magnitude diagram to remove the contamination of field stars. We also performed N-body simulations in order to help us to understand the spatial distribution of the extra-tidal debris. The outcomes reveal the presence of long trailing and leading tails that are mostly parallel to the direction of the cluster velocity vector. We find that the cluster loses most of its mass by tidal disruption during its perigalactic passages, each of which lasted nearly 20 Myr. Hence, a decrease in the density of escaping stars near the cluster is expected from our N-body simulations, which, in turn, means that stronger extra-tidal features could be found by exploring much larger areas around NGC 6891.
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    The tidal tails of Milky Way globular clusters
    (2020) Piatti, Andres E.; Carballo-Bello, Julio A.
    We report on the search for overall kinematical or structural conditions that have allowed some Milky Way globular clusters to develop tidal tails. For this purpose, we built a comprehensive catalog of globular clusters with studies focused on their outermost regions and we classify the globular clusters in three categories: those with observed tidal tails, those with extra-tidal features that are different from tidal tails, and those without any signatures of extended stellar density profiles. When exploring different kinematical and structural parameter spaces, we found that globular clusters behave similarly, irrespective of the presence of tidal tails or any other kind of extra-tidal feature, or the absence thereof. In general, globular clusters whose orbits are relatively more eccentric and very inclined, with respect to the Milky Way plane, have undergone a larger amount of mass loss by tidal disruption. The latter has also accelerated the internal dynamics toward a comparatively more advanced stage of evolution. These outcomes show that it is not straightforward to find any particular set of parameter space and dynamical conditions that can definitely predict tidal tails along globular clusters in the Milky Way.
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    Using Gaia DR2 to detect extratidal structures around the Galactic globular cluster NGC362
    (2019) Carballo-Bello, Julio A.
    We explore the possibility of searching for extratidal features around the Galactic globular cluster NGC362 using the Gaia DR2 (second data release) together with a modified version of a classical statistical decontamination algorithm. Our results suggest that an important stellar component is associated with this globular cluster, which is perfectly distinguishable from the populations in the Small Magellanic Cloud and that of the nearby NGC104 (47 Tucanae). We thus confirm once again the power of Gaia to disentangle different stellar components along the same line of sight.
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    Variable stars in the VVV globular clusters. II. NGC 6441, NGC 6569, NGC 6626 (M 28), NGC 6656 (M 22), 2MASS-GC 02, and Terzan 10
    (2021) Alonso-García, Javier; Smith, Leigh C.; Catelan, Márcio; Minniti, Dante; Navarrete, Camila; Borissova, Jura; Carballo-Bello, Julio A.; Contreras Ramos, Rodrigo; Fernández-Trincado, José G.; Ferreira Lopes, Carlos E.; Gran, Felipe; Garro, Elisa R.; Geisler, Doug; Guo, Zhen; Hempel, Maren; Kerins, Eamonn; Lucas, Philip W.; Palma, Tali; Peña Ramírez, Karla; Ramírez Alegría, Sebastián; Saito, Roberto K.
    Context. The Galactic globular clusters (GGCs) located in the inner regions of the Milky Way suffer from high extinction that makes their observation challenging. High densities of field stars in their surroundings complicate their study even more. The VISTA Variables in the Via Lactea (VVV) survey provides a way to explore these GGCs in the near-infrared where extinction effects are highly diminished. Aims: We conduct a search for variable stars in several inner GGCs, taking advantage of the unique multi-epoch, wide-field, near-infrared photometry provided by the VVV survey. We are especially interested in detecting classical pulsators that will help us constrain the physical parameters of these GGCs. In this paper, the second of a series, we focus on NGC 6656 (M 22), NGC 6626 (M 28), NGC 6569, and NGC 6441; these four massive GGCs have known variable sources, but quite different metallicities. We also revisit 2MASS-GC 02 and Terzan 10, the two GGCs studied in the first paper of this series. Methods: We present an improved method and a new parameter that efficiently identify variable candidates in the GGCs. We also use the proper motions of those detected variable candidates and their positions in the sky and in the color-magnitude diagrams to assign membership to the GGCs. Results: We identify and parametrize in the near-infrared numerous variable sources in the studied GGCs, cataloging tens of previously undetected variable stars. We recover many known classical pulsators in these clusters, including the vast majority of their fundamental mode RR Lyrae. We use these pulsators to obtain distances and extinctions toward these objects. Recalibrated period-luminosity-metallicity relations for the RR Lyrae bring the distances to these GGCs to a closer agreement with those reported by Gaia, except for NGC 6441, which is an uncommon Oosterhoff III GGC. Recovered proper motions for these GGCs also agree with those reported by Gaia, except for 2MASS-GC 02, the most reddened GGC in our sample, where the VVV near-infrared measurements provide a more accurate determination of its proper motions. Lightcurves and full Tables 2, 5, 6, 7, 8, and 9 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/651/A47...
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    Whiting 1: Confirmation of its accretion by the Milky Way
    (2017) Carballo-Bello, Julio A.; Corral-Santana, Jesús M.; Martínez-Delgado, David; Sollima, Antonio; Muñoz, Ricardo R.; Duffau, Sonia; Catelan, Marcio
    We investigate the association of Whiting 1 with the Sagittarius tidal stream by obtaining radial velocities for a sample of 101 stars observed with VIMOS. Our results reveal the presence of a component of the Sagittarius tidal stream with a radial velocity - and distance - compatible with that of the globular cluster. Therefore, we conclude that Whiting1 was formed in the interior of the Sagittarius dwarf spheroidal galaxy and later accreted by the Milky Way. In addition, our data also reveal the detection for the first time of an ancient wrap of the Sagittarius tidal stream along the same line-of-sight and at the same heliocentric distance....