skip to main content

SciTech ConnectSciTech Connect

Title: Milky Way red dwarfs in the BoRG survey; galactic scale-height and the distribution of dwarf stars in WFC3 imaging

We present a tally of Milky Way late-type dwarf stars in 68 Wide Field Camera 3 (WFC3) pure-parallel fields (227 arcmin{sup 2}) from the Brightest of Reionizing Galaxies survey for high-redshift galaxies. Using spectroscopically identified M-dwarfs in two public surveys, the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey and the Early Release Science mosaics, we identify a morphological selection criterion using the half-light radius (r {sub 50}), a near-infrared J – H, G – J color region where M-dwarfs are found, and a V – J relation with M-dwarf subtype. We apply this morphological selection of stellar objects, color-color selection of M-dwarfs, and optical-near-infrared color subtyping to compile a catalog of 274 M-dwarfs belonging to the disk of the Milky Way with a limiting magnitude of m {sub F125W} < 24(AB). Based on the M-dwarf statistics, we conclude that (1) the previously identified north-south discrepancy in M-dwarf numbers persists in our sample; there are more M-dwarfs in the northern fields on average than in southern ones, (2) the Milky Way's single disk scale-height for M-dwarfs is 0.3-4 kpc, depending on subtype, (3) the scale-height depends on M-dwarf subtype with early types (M0-4) high scale-height (z {sub 0} = 3-4 kpc)more » and later types M5 and above in the thin disk (z {sub 0} = 0.3-0.5 kpc), (4) a second component is visible in the vertical distribution, with a different, much higher scale-height in the southern fields compared to the northern ones. We report the M-dwarf component of the Sagittarius stream in one of our fields with 11 confirmed M-dwarfs, seven of which are at the stream's distance. In addition to the M-dwarf catalog, we report the discovery of 1 T-dwarfs and 30 L-dwarfs from their near-infrared colors. The dwarf scale-height and the relative low incidence in our fields of L- and T-dwarfs in these fields makes it unlikely that these stars will be interlopers in great numbers in color-selected samples of high-redshift galaxies. The relative ubiquity of M-dwarfs however will make them ideal tracers of Galactic halo substructure with EUCLID and reference stars for James Webb Space Telescope observations.« less
Authors:
;  [1] ;  [2] ;  [3] ; ; ; ; ;  [4] ;  [5] ;  [6]
  1. Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)
  2. Kavli Institute for Cosmology and Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom)
  3. Department of Natural Sciences College of Arts, Sciences and Letters, University of Michigan-Dearborn 4901 Evergreen Road, Dearborn, MI 48128 (United States)
  4. Space Telescope Science Institute, Baltimore, MD 21218 (United States)
  5. European Space Agency, ESA-ESTEC, Keplerlaan 1, 2200 AG Noordwijk (Netherlands)
  6. UJF-Grenoble 1/CNRS-INSU, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, F-38041 Grenoble (France)
Publication Date:
OSTI Identifier:
22356638
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 788; 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; CATALOGS; COLOR; COMPARATIVE EVALUATIONS; DISTANCE; DISTRIBUTION; DWARF STARS; MASS; MILKY WAY; RED SHIFT; SCALE HEIGHT; SPACE; STREAMS; TELESCOPES; VISIBLE RADIATION