We present a tally of Milky Way late-type dwarf stars in 68 Wide Field Camera 3 (WFC3) pure-parallel fields (227 arcmin 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 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 F 125W < 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 Land 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.
We have identified 274 M-type Brown Dwarfs in the Hubble Space Telescope's Wide Field Camera 3 (WFC3) pure parallel fields from the Brightest of Reionizing Galaxies (BoRG) survey for high redshift galaxies. These are near-infrared observations with multiple lines-of-sight out of our Milky Way. Using these observed M-type Brown Dwarfs we fitted a Galactic disk and halo model with a Markov chain Monte Carlo (MCMC) analysis. This model worked best with the scale length of the disk fixed at h = 2.6 kpc. For the scale height of the disk, we found z 0 = 0.29 +0.02 −0.019 kpc and for the central number density ρ 0 = 0.29 +0.20 −0.13 #/pc 3 . For the halo we derived a flattening parameter κ = 0.45±0.04 and a power-law index p = 2.4±0.07. We found the fraction of M-type brown dwarfs in the local density that belong to the halo to be f h = 0.0075 +0.0025 −0.0019 . We found no correlation between subtype of M-dwarf and any model parameters. The total number of M-type Brown Dwarfs in the disk and halo was determined to be 58.2 +9.81 −6.70 × 10 9 . We found an upper limit for the fraction of M-type Brown Dwarfs in the halo of 7 +5 −4 %. The upper limit for the total Galactic Disk mass in M-dwarfs is 4.34 +0.73 −0.5 × 10 9 M , assuming all M-type Brown Dwarfs have a mass of 80M J .
We present a tally of Milky Way late-type dwarf stars in 68 WFC3 pure-parallel fields (227 arcmin 2 ) from the Brightest of Reionizing Galaxies (BoRG) survey for high-redshift galaxies. Using spectroscopically identified M-dwarfs in two public surveys, the CANDELS and the ERS 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 opticalnear-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 F 125W < 24(AB). Based on the M-dwarfs statistics, we conclude that (a) 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, (b) the Milky Way's single disk scale-height for M-dwarfs is 0.3-4 kpc, depending on sub-type, (c) the scale-height depends on M-dwarf subtype with early type (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). (d) 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 Mdwarfs, 7 of which are at the stream's distance In addition to the M-dwarf catalog, we report the discovery of 1 T-dwarf 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 go 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 JWST observations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.