Browsing by Author "Gran, Felipe"

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    Pulsating stars in ω Centauri. Near-IR properties and period-luminosity relations
    (2017) Navarrete, Camila; Catelan, Marcio; Contreras Ramos, Rodrigo; Alonso-García, Javier; Gran, Felipe; Dékány, István; Minniti, Dante
    ω Centauri (NGC 5139) contains many variable stars of different types, including the pulsating type II Cepheids, RR Lyrae and SX Phoenicis stars. We carried out a deep, wide-field, near-infrared (IR) variability survey of ω Cen, using the VISTA telescope. We assembled an unprecedented homogeneous and complete J and KS near-IR catalog of variable stars in the field of ω Cen. In this paper we compare optical and near-IR light curves of RR Lyrae stars, emphasizing the main differences. Moreover, we discuss the ability of near-IR observations to detect SX Phoenicis stars given the fact that the amplitudes are much smaller in these bands compared to the optical. Finally, we consider the case in which all the pulsating stars in the three different variability types follow a single period-luminosity relation in the near-IR bands....
  • Thumbnail Image
    Item
    The Orbit of the New Milky Way Globular Cluster FSR1716 =VVV-GC05
    (2018) Contreras Ramos, Rodrigo Andrés; Minniti, D.; Fernández Trincado, José G.; Alonso García, Javier; Catelan, Márcio; Gran, Felipe; Hajdu, Gergely; Hempel, Maren; Rojas Arriagada, Álvaro; Zoccali, Manuela
  • Thumbnail Image
    Item
    The VVV Survey RR Lyrae Population in the Galactic Center Region
    (2018) Contreras Ramos, Rodrigo Andrés; Minniti, D.; Gran, Felipe; Zoccali, Manuela; Alonso-Garcia, Javier; Huijse, Pablo; Gabriela Navarro, Maria; Rojas-Arriagada, Alvaro; Valenti, Elena
  • Thumbnail Image
    Item
    Variable stars in the VVV globular clusters. I. 2MASS-GC 02 and Terzan 10
    (2015) Alonso García, Javier; Dékány, István; Catelan, Márcio; Gran, Felipe; Amigo, Pía; Leyton, Paul; Minniti, D.
  • Thumbnail Image
    Item
    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...
  • No Thumbnail Available
    Item
    Variable Stars in VVV Globular Clusters
    (2015) Contreras Ramos, Rodrigo; Alonso-Garcia, Javier; Minniti, Dante; Catelan, Márcio; Zoccali, Manuela; Gran, Felipe; Dekany, Istvan
    The Vista Variables in the Via Lactea (VVV) is an ongoing variability survey observing the central regions of our Galaxy in the near-infrared by means of the VISTA telescope. Numerous (36) inner Galactic globular clusters fall inside the area covered by the VVV survey. Most of these clusters, especially the faintest ones, have been poorly studied in the past due to the difficulties caused by the presence of an elevated extinction and high field stellar densities in their lines of sight. We will present the first results of a search for variable stars we are conducting in some of these clusters. Our main aim is to obtain a better determination of the physical parameters of these globular clusters and put constrains on the formation scenario of our galaxy using the information provided by their variables stars.