Examinando por Autor "Marconi, Marcella"
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Ítem 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, MarcellaThe 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 clusterÍtem 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.