Examinando por Autor "Ripepi, Vincenzo"

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    Discovery of tidal RR lyrae stars in the bulge globular cluster M62
    (Institute of Physics Publishing, 2018-12) Minniti, Dante; Fernández-Trincado, José G.; Ripepi, Vincenzo; Alonso-García, Javier; Contreras Ramos, Rodrigo; Marconi, Marcella
    The RR Lyrae (RRL) rich globular cluster M62 (NGC 6266) is one of the most massive globular clusters in the Milky Way, located in the dense region of the Galactic bulge, where dynamical processes that affect the survival of globular clusters are maximized. Using Gaia second data release data we have found clear evidence for an excess of RRLs beyond the cluster tidal radius of M62, associated partly with stars stripped into the Galaxy field. This is confirmed with new Visible and Infrared Survey Telescope for Astronomy Variables in the Via Lactea Extended survey observations, which discard any differential reddening effect as the possible cause of the observed RRL density excess. We also determined the orbit of M62 using accurate new measurements of its distance, radial velocity, and proper motions, finding that its orbit is prograde with respect to the direction of the Galactic rotation. Orbits are integrated in the non-axisymmetric galactic model GravPot16, which includes the perturbations due to the central Galactic bar. M62 shows a particular orbital behavior, having a dynamical signature of the bar-bulge region. The small extra-tidal RRLs extensions that are observed are roughly aligned toward the galactic center, and the direction is almost perpendicular to the galactic plane, not with its motion along its orbit. This may be a clear sign of bulge-crossing shocks during the last passage close of the cluster toward its perigalacticon. M62 would be the first clear observed case of bulge shocking in the inner Galaxy acting on a globular cluster
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    Impact of Distance Determinations on Galactic Structure. II. Old Tracers
    (Springer Netherlands, 2018-08) Kunder, Andrea; Valenti, Elena; Dall’Ora, Massimo; Pietrukowicz, Pawel; Sneden, Chris; Bono, Giuseppe; Braga, Vittorio F.; Ferraro, Iván; Fiorentino, Giuliana; Iannicola, Giacinto; Marconi, Marcella; Martínez-Vázquez, Clara E.; Monelli, Matteo; Musella, Ilaria; Ripepi, Vincenzo; Salaris, Maurizio; Stetson, Peter B.
    Here we review the efforts of a number of recent results that use old tracers to understand the build up of the Galaxy. Details that lead directly to using these old tracers to measure distances are discussed. We concentrate on the following: (1) the structure and evolution of the Galactic bulge and inner Galaxy constrained from the dynamics of individual stars residing therein; (2) the spatial structure of the old Galactic bulge through photometric observations of RR Lyrae-type stars; (3) the three-dimensional structure, stellar density, mass, chemical composition, and age of the Milky Way bulge as traced by its old stellar populations; (4) an overview of RR Lyrae stars known in the ultra-faint dwarfs and their relation to the Galactic halo; and (5) different approaches for estimating absolute and relative cluster ages. © 2018, Springer Nature B.V.
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    Rubin Observatory LSST Transients and Variable Stars Roadmap
    (Institute of Physics, 2023-10) Hambleton, Kelly M.; Bianco, Federica B.; Street, Rachel; Bell, Keaton; Buckley, David; Graham, Melissa; Hernitschek, Nina; Lund, Michael B.; Mason, Elena; Pepper, Joshua; Prša, Andrej; Rabus, Markus; Raiteri, Claudia M.; Szabó, Róbert; Szkody, Paula; Andreoni, Igor; Antoniucci, Simone; Balmaverde, Barbara; Bellm, Eric; Bonito, Rosaria; Bono, Giuseppe; Botticella, Maria Teresa; Brocato, Enzo; Bricman, Katja Bučar; Cappellaro, Enrico; Carnerero, Maria Isabel; Chornock, Ryan; Clarke, Riley; Cowperthwaite, Phil; Cucchiara, Antonino; D’Ammando, Filippo; Dage, Kristen C.; Dall’Ora, Massimo; Davenport, James R.A.; de Martino, Domitilla; de Somma, Giulia; Criscienzo, Marcella Di; Stefano, Rosanne Di; Drout, Maria; Fabrizio, Michele; Fiorentino, Giuliana; Gandhi, Poshak; Garofalo, Alessia; Giannini, Teresa; Gomboc, Andreja; Greggio, Laura; Hartigan, Patrick; Hundertmark, Markus; Johnson, Elizabeth; Johnson, Michael; Jurkic, Tomislav; Khakpash, Somayeh; Leccia, Silvio; Li, Xiaolong; Magurno, Davide; Malanchev, Konstantin; Marconi, Marcella; Margutti, Raffaella; Marinoni, Silvia; Mauron, Nicolas; Molinaro, Roberto; Möller, Anais; Moniez, Marc; Muraveva, Tatiana; Musella, Ilaria; Ngeow, Chow-Choong; Pastorello, Andrea; Petrecca, Vincenzo; Piranomonte, Silvia; Ragosta, Fabio; Reguitti, Andrea; Righi, Chiara; Ripepi, Vincenzo; Rivera Sandoval, Liliana; Stassun, Keivan G.; Stroh, Michael; Terreran, Giacomo; Trimble, Virginia; Tsapras, Yiannis; van Velzen, Sjoert; Venuti, Laura; Vink, Jorick S.
    The Vera C. Rubin Legacy Survey of Space and Time (LSST) holds the potential to revolutionize time domain astrophysics, reaching completely unexplored areas of the Universe and mapping variability time scales from minutes to a decade. To prepare to maximize the potential of the Rubin LSST data for the exploration of the transient and variable Universe, one of the four pillars of Rubin LSST science, the Transient and Variable Stars Science Collaboration, one of the eight Rubin LSST Science Collaborations, has identified research areas of interest and requirements, and paths to enable them. While our roadmap is ever-evolving, this document represents a snapshot of our plans and preparatory work in the final years and months leading up to the survey’s first light. © 2023 Institute of Physics Publishing. All rights reserved.
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    The globular cluster systems of the milky way and the Sagittarius dwarf galaxy
    (Universidad Andrés Bello, 2023) Garro, Elisa Rita; Minniti, D.; Fernández Trincado, Jose Gregorio; Gómez, Matías; Alonso García, Javier; Ripepi, Vincenzo; Facultad de Ciencias Exactas
    The VISTA Variables in the Via Lactea Survey (VVV) and its Extension (VVVX) allow us to probe ´ previously unexplored regions of the inner Milky Way (MW), especially those that are affected by stellar crowding and strong extinction. My long-term goal is to identify new star clusters and investigate them to reveal their true nature. In particular, I am looking for new candidate globular clusters (GCs) located in the Galactic bulge and disk, with the aim of completing the census of the MW GC system. I searched and characterized new star clusters, using a combination of the near-infrared (IR) VVV-VVVX survey and Two Micron All Sky survey (2MASS) datasets, and the optical Gaia Data Releases (DR2, EDR3 and DR3) photometry and its precise astrometry and proper motions (PMs). Performing a PM-decontamination procedure, I built final catalogues with high-likely cluster members, on which I carried out a detailed photometric analysis. I estimated the main physical parameters, such as reddenings and extinction, heliocentric and Galactocentric distances, mean cluster PMs, metallicities, ages, integrated luminosities, and structural parameters (core and tidal radii). I analysed 34 new GC candidates in the MW and 21 in the Sagittarius dwarf galaxies, confirming (photometrically) the GC nature for 17 of them, and 4 are old open clusters in the MW bulge and disk, whereas other 17 GCs belonging to the Sagittarius dwarf galaxy. Finally, for 11 bound systems, I collected radial velocity informations (from H-/K-band spectra and/or Gaia DR3 datasets) in order to reconstruct their orbital history for the first time, thus associating these clusters to the relative Galactic components and understand their (in-situ or ex-situ) origin.
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    The RR Lyrae projected density distribution from the Galactic centre to the halo
    (EDP Sciences, 2021-02-01) Navarro, María Gabriela; Minniti, Dante; Capuzzo-Dolcetta, Roberto; Alonso-García, Javier; Contreras Ramos, Rodrigo; Majaess, Daniel; Ripepi, Vincenzo
    The projected density distribution of type ab RR Lyrae (RRab) stars was characterised from the innermost regions of the Milky Way to the halo, with the aim of placing constraints on the Galaxy's evolution. The compiled sample (NRRab = 64 850) stems from fundamental mode RR Lyrae variables identified by the VVV, OGLE, and Gaia surveys. The distribution is well fitted by three power laws over three radial intervals. In the innermost region (R < 2.2°) the distribution follows ςRRab[1] R-0.94 ± 0.051, while in the external region the distribution adheres to ςRRab[2] R-1.50 ± 0.019 for 2.2° < R < 8.0° and ςRRab[3] R-2.43 ± 0.043 for 8.0° < R < 30.0°. Conversely, the cumulative distribution of red clump (RC) giants exhibits a more concentrated distribution in the mean, but in the central R < 2.2° the RRab population is more peaked, whereas globular clusters (GCs) follow a density power law (ςGCs R-1.59 ± 0.060 for R < 30.0°) similar to that of RRab stars, especially when considering a more metal-poor subsample ([Fe/H] < -1.1 dex). The main conclusion emerging from the analysis is that the RRab distribution favours the star cluster infall and merger scenario for creating an important fraction (> 18%) of the central Galactic region. The radii containing half of the populations (half populations radii) are RH RRab = 6.8° (0.99 kpc), RH RC = 4.2° (0.61 kpc), and RH GCs = 11.9° (1.75 kpc) for the RRab stars, RC giants, and GCs, respectively. Finally, merely ∼1% of the stars have been actually discovered in the innermost region (R < 35 pc) out of the expected (based on our considerations) total number of RRab therein: N ∼ 1562. That deficit will be substantially ameliorated with future space missions like the Nancy Grace Roman Space Telescope (formerly WFIRST).