Milky Way Red Dwarfs in the BoRG Survey; Galactic Scale-height and the Distribution of Dwarf Stars in WFC3 Imaging - Archive ouverte HAL Access content directly
Journal Articles The Astrophysical Journal Year : 2014

Milky Way Red Dwarfs in the BoRG Survey; Galactic Scale-height and the Distribution of Dwarf Stars in WFC3 Imaging

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1
B. W. Holwerda
  • Function : Author
M. Trenti
  • Function : Author
W. Clarkson
  • Function : Author
K. Sahu
  • Function : Author
L. Bradley
  • Function : Author
M. Stiavelli
  • Function : Author
N. Pirzkal
  • Function : Author
G. de Marchi
  • Function : Author
R. Bouwens
  • Function : Author
R. Ryan
  • Function : Author

Abstract

We present a tally of Milky Way late-type dwarf stars in 68 Wide Field Camera 3 (WFC3) pure-parallel fields (227 arcmin2) 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 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 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 0 = 3-4 kpc) and later types M5 and above in the thin disk (z 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.

Dates and versions

insu-03618573 , version 1 (24-03-2022)

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Cite

B. W. Holwerda, M. Trenti, W. Clarkson, K. Sahu, L. Bradley, et al.. Milky Way Red Dwarfs in the BoRG Survey; Galactic Scale-height and the Distribution of Dwarf Stars in WFC3 Imaging. The Astrophysical Journal, 2014, 788, ⟨10.1088/0004-637X/788/1/77⟩. ⟨insu-03618573⟩
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