skip to main content

SciTech ConnectSciTech Connect

Title: Parallaxes of southern extremely cool objects (parsec). II. Spectroscopic follow-up and parallaxes of 52 targets

We present near-infrared spectroscopy for 52 ultracool dwarfs, including two newly discovered late-M dwarfs, one new late-M subdwarf candidate, three new L, and four new T dwarfs. We also present parallaxes and proper motions for 21 of them. Four of the targets presented here have previous parallax measurements, while all the others are new values. This allow us to populate further the spectral sequence at early types (L0-L4). Combining the astrometric parameters with the new near-infrared spectroscopy presented here, we are able to investigate further the nature of some of the objects. In particular, we find that the peculiar blue L1 dwarf SDSS J133148.92–011651.4 is a metal-poor object, likely a member of the galactic thick disk. We discover a new M subdwarf candidate, 2MASS J20115649–6201127. We confirm the low-gravity nature of EROS-MP J0032–4405, DENIS-P J035726.9–441730, and 2MASS J22134491–2136079. We present two new metal-poor dwarfs: the L4pec 2MASS J19285196–4356256 and the M7pec SIPS2346–5928. We also determine the effective temperature and bolometric luminosity of the 21 targets with astrometric measurements, and we obtain a new polynomial relation between effective temperature and near-infrared spectral type. The new fit suggests a flattening of the sequence at the transition between M and L spectral types.more » This could be an effect of dust formation, which causes a more rapid evolution of the spectral features as a function of the effective temperature.« less
Authors:
; ; ; ; ;  [1] ; ; ;  [2] ;  [3] ;  [4]
  1. Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom)
  2. INAF/Osservatorio Astrofisico di Torino, Strada Osservatorio 20, I-10025 Pino Torinese (Italy)
  3. Departamento de Astronomia, Universidad de Chile, Camino del Observatorio 1515, Santiago (Chile)
  4. Observatório Nacional/MCT, R. Gal. José Cristino 77, CEP20921-400 RJ (Brazil)
Publication Date:
OSTI Identifier:
22340059
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 146; Journal Issue: 6; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION SPECTROSCOPY; BOLOMETERS; DATA; DUSTS; DWARF STARS; EVOLUTION; GRAVITATION; INFRARED SPECTRA; LUMINOSITY; NEAR INFRARED RADIATION; POLYNOMIALS; PROPER MOTION; STARS