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Title: CLUSTERED CEPHEID VARIABLES 90 KILOPARSECS FROM THE GALACTIC CENTER

Distant regions close to the plane of our Galaxy are largely unexplored by optical surveys as they are hidden by dust. We have used near-infrared data (which minimizes dust obscuration) from the ESO Public survey VISTA Variables of the Via Lactea to search for distant stars at low latitudes. We have discovered four Cepheid variables within an angular extent of 1° centered at a Galactic longitude of l = −27.°4 and a Galactic latitude of b = −1.°08. We use the tightly constrained period–luminosity relationship that these pulsating stars obey to derive distances. We infer an average distance to these Cepheid variables of 90 kpc. The Cepheid variables are highly clustered in angle (within 1°) and in distance (the standard deviation of the distances is 12 kpc). These young (∼100 Myr old), pulsating stars are unexpected at such large distances from the Galactic disk, which terminates at ∼15 kpc. The highly clustered nature in distance and angle of the Cepheid variables suggests that the stars may be associated with a dwarf galaxy; its location and mass were earlier predicted by a dynamical analysis. The Cepheids are at an average distance of ∼2 kpc from the plane and their maximum projectedmore » separation is ∼1 kpc.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ; ;  [5]
  1. School of Physics and Astronomy, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623 (United States)
  2. Departamento de Fisica-Universidade Federal de Sergipe, Rod. Marechal Rondon s/n-Jardim Rosa Elze, Sao Cristovao, 49.100-000, Sergipe (Brazil)
  3. Department of Physics and Astronomy, University of Rochester, Rochester NY 14627 (United States)
  4. Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica of Chile, Av. Vicuña Mackenna 4860, Santiago (Chile)
  5. Astronomy Department, UC Berkeley, Berkeley CA 94720 (United States)
Publication Date:
OSTI Identifier:
22518821
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 802; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CEPHEIDS; COSMIC DUST; DISTANCE; LUMINOSITY; MASS; MILKY WAY; STAR CLUSTERS