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Title: The trends high-contrast imaging survey. V. Discovery of an old and cold benchmark T-dwarf orbiting the nearby G-star HD 19467

The nearby Sun-like star HD 19467 shows a subtle radial velocity (RV) acceleration of –1.37 ± 0.09 m s{sup –1} yr{sup –1} over a 16.9 yr time baseline (an RV trend), hinting at the existence of a distant orbiting companion. We have obtained high-contrast images of the star using NIRC2 at Keck Observatory and report the direct detection of the body that causes the acceleration. The companion, HD 19467 B, is ΔK{sub s} = 12.57 ± 0.09 mag fainter than its parent star (contrast ratio of 9.4 × 10{sup –6}), has blue colors J – K{sub s} = –0.36 ± 0.14 (J – H = –0.29 ± 0.15), and is separated by ρ = 1.''653 ± 0.''004 (51.1 ± 1.0 AU). Follow-up astrometric measurements obtained over a 1.1 yr time baseline demonstrate physical association through common parallactic and proper motion. We calculate a firm lower-limit of m≥51.9{sub −4.3}{sup +3.6}M{sub J} for the companion mass from orbital dynamics using a combination of Doppler observations and imaging. We estimate a model-dependent mass of m=56.7{sub −7.2}{sup +4.6}M{sub Jup} from a gyrochronological age of 4.3{sub −1.2}{sup +1.0} Gyr. Isochronal analysis suggests a much older age of 9 ± 1 Gyr, which corresponds to amore » mass of m=67.4{sub −1.5}{sup +0.9}M{sub J}. HD 19467 B's measured colors and absolute magnitude are consistent with a late T dwarf [≈T5-T7]. We may infer a low metallicity of [Fe/H] =–0.15 ± 0.04 for the companion from its G3V parent star. HD 19467 B is the first directly imaged benchmark T dwarf found orbiting a Sun-like star with a measured RV acceleration.« less
Authors:
 [1] ;  [2] ;  [3] ; ;  [4] ; ;  [5] ;  [6]
  1. Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States)
  2. Harvard Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  3. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
  4. Department of Astronomy, University of California, Berkeley, CA 94720 (United States)
  5. Department of Physics, Yale University, New Haven, CT 06511 (United States)
  6. Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)
Publication Date:
OSTI Identifier:
22348177
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 781; 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; ACCELERATION; BENCHMARKS; COLOR; DETECTION; DWARF STARS; IMAGES; MASS; METALLICITY; RADIAL VELOCITY; RESOLUTION; SUN