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Title: The κ Andromedae system: new constraints on the companion mass, system age, and further multiplicity

κ Andromedae is a B9IVn star at 52 pc for which a faint substellar companion separated by 55 ± 2 AU was recently announced. In this work, we present the first spectrum of the companion, 'κ And B,' using the Project 1640 high-contrast imaging platform. Comparison of our low-resolution YJH-band spectra to empirical brown dwarf spectra suggests an early-L spectral type. Fitting synthetic spectra from PHOENIX model atmospheres to our observed spectrum allows us to constrain the effective temperature to ∼2000 K as well as place constraints on the companion surface gravity. Further, we use previously reported log(g) and T {sub eff} measurements of the host star to argue that the κ And system has an isochronal age of 220 ± 100 Myr, older than the 30 Myr age reported previously. This interpretation of an older age is corroborated by the photometric properties of κ And B, which appear to be marginally inconsistent with other 10-100 Myr low-gravity L-dwarfs for the spectral type range we derive. In addition, we use Keck aperture masking interferometry combined with published radial velocity measurements to rule out the existence of any tight stellar companions to κ And A that might be responsible for themore » system's overluminosity. Further, we show that luminosity enhancements due to a nearly 'pole-on' viewing angle coupled with extremely rapid rotation is unlikely. κ And A is thus consistent with its slightly evolved luminosity class (IV), and we propose here that κ And, with a revised age of 220 ± 100 Myr, is an interloper to the 30 Myr Columba association with which it was previously associated. The photometric and spectroscopic evidence for κ And B combined with our reassessment of the system age implies a substellar companion mass of 50{sub −13}{sup +16} M {sub Jup}, consistent with a brown dwarf rather than a planetary-mass companion.« less
Authors:
; ;  [1] ;  [2] ;  [3] ; ; ; ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ; ; ;  [9] ;  [10] ;  [11] ;  [12] ;  [13] more »; « less
  1. Department of Astronomy, California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125 (United States)
  2. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
  3. Department of Astronomy, Universidad de Chile Cerro Calan, Las Condes (Chile)
  4. Astrophysics Department, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States)
  5. Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627-0171 (United States)
  6. Harvard-Smithsonian CfA, 60 Garden Street, Cambridge, MA 02140 (United States)
  7. Department of Engineering Science and Physics, College of Staten Island, City University of New York, Staten Island, NY 10314 (United States)
  8. Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109 (Australia)
  9. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)
  10. Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)
  11. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
  12. NASA Exoplanet Science Institute, California Institute of Technology, Pasadena, CA 91125 (United States)
  13. Caltech Optical Observatories, California Institute of Technology, Pasadena, CA 91125 (United States)
Publication Date:
OSTI Identifier:
22348430
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 779; 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; APERTURES; ATMOSPHERES; COMPARATIVE EVALUATIONS; DETECTION; GRAVITATION; INTERFEROMETERS; INTERFEROMETRY; LIMITING VALUES; LUMINOSITY; MASS; MULTIPLICITY; RADIAL VELOCITY; RESOLUTION; ROTATION; SATELLITES; SPECTRA; STARS; SURFACES