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Title: DIRECT IMAGING AND SPECTROSCOPY OF A CANDIDATE COMPANION BELOW/NEAR THE DEUTERIUM-BURNING LIMIT IN THE YOUNG BINARY STAR SYSTEM, ROXs 42B

We present near-infrared high-contrast imaging photometry and integral field spectroscopy of ROXs 42B, a binary M0 member of the 1-3 Myr old ρ Ophiuchus star-forming region, from data collected over 7 years. Each data set reveals a faint companion—ROXs 42Bb—located ∼1.''16 (r {sub proj} ≈ 150 AU) from the primaries at a position angle consistent with a point source identified earlier by Ratzka et al.. ROXs 42Bb's astrometry is inconsistent with a background star but consistent with a bound companion, possibly one with detected orbital motion. The most recent data set reveals a second candidate companion at ∼0.''5 of roughly equal brightness, though preliminary analysis indicates it is a background object. ROXs 42Bb's H and K{sub s} band photometry is similar to dusty/cloudy young, low-mass late M/early L dwarfs. K band VLT/SINFONI spectroscopy shows ROXs 42Bb to be a cool substellar object (M8-L0; T {sub eff} ≈ 1800-2600 K), not a background dwarf star, with a spectral shape indicative of young, low surface gravity planet-mass companions. We estimate ROXs 42Bb's mass to be 6-15 M{sub J} , either below the deuterium-burning limit and thus planet mass or straddling the deuterium-burning limit nominally separating planet-mass companions from other substellar objects. Given ROXs 42b's projected separation and massmore » with respect to the primaries, it may represent the lowest mass objects formed like binary stars or a class of planet-mass objects formed by protostellar disk fragmentation/disk instability, the latter slightly blurring the distinction between non-deuterium-burning planets like HR 8799 bcde and low-mass, deuterium-burning brown dwarfs.« less
Authors:
; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6]
  1. Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON (Canada)
  2. Space Telescope Science Institute, Baltimore, MD (United States)
  3. Dèpartment de Physique, Université de Montreal, Montréal, QC (Canada)
  4. Nishi-Harima Observatory, University of Hyogo, Kobe (Japan)
  5. Universitäts-Sternwarte München, Ludwig-Maximilians-Universität, München (Germany)
  6. Institute for Astronomy, University of Hawaii, Pukalani, HI (United States)
Publication Date:
OSTI Identifier:
22364043
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 780; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; BINARY STARS; DEUTERIUM; DWARF STARS; GRAVITATION; INTEGRALS; MASS; PHOTOMETRY; PLANETS; POINT SOURCES; SPECTROSCOPY; STAR EVOLUTION; SURFACES