HD 20781

HD 20781 is a star which is part of a wide binary system with HD 20782. The companion star has a very large angular separation of 252 arcsec, corresponding to 9080 AU at the distance of HD 20782.[4] Both stars possess their own planetary systems in S type orbits. This is the first time that planets have been found in both components of a wide binary system.[4][5][6]

HD 20781
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Fornax[1]
Right ascension  03h 20m 02.943s[2]
Declination –28° 47′ 01.80″[2]
Apparent magnitude (V) 8.44
Characteristics
Spectral type G9.5V
Astrometry
Proper motion (μ) RA: 348.97 ± 0.71[2] mas/yr
Dec.: –67.69 ± 0.91[2] mas/yr
Parallax (π)28.27 ± 1.08[2] mas
Distance115 ± 4 ly
(35 ± 1 pc)
Other designations
CD–29° 1229, HIP 15526, LTT 1581, SAO 168468[3]
Database references
SIMBADdata

Planetary system

HD 20781
The HD 20781 planetary system[5]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 12.04 ± 1.11 M⊕ 0.169 ± 0.0028 29.15 ± 0.0201 0.11 ± 0.06 — —
c 15.76 ± 1,20 M⊕ 0.3456 ± 0.0047 85.131 ± 0.1161 0.28 ± 0.09 — —
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See also
  • List of extrasolar planets
  • XO-2, a wide binary star in the constellation Lynx

References
  1. Roman, Nancy G. (1987). "Identification of a Constellation From a Position". Publications of the Astronomical Society of the Pacific. 99 (617): 695–699. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Vizier query form
  2. van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.Vizier catalog entry
  3. "HD 20781 -- High proper-motion Star". SIMBAD Astronomical Database. Centre de données astronomiques de Strasbourg. Retrieved 2014-09-10.
  4. Properties of planets in binary systems.
  5. Schneider, J. "Notes for star HD 20781". The Extrasolar Planets Encyclopaedia. Retrieved 2011-09-12.
  6. Mayor, M. Marmier,M. Lovis,C. Udry,S. Ségransan,D. Pepe,F. Benz,W. Bertaux,J.-L. Bouchy,F. Dumusque, G. Curto,Lo Mordasini,C. Queloz,D. Santos,N. C.; et al. (2011). "The HARPS search for southern extra-solar planets XXXIV. Occurrence, mass distribution and orbital properties of super-Earths and Neptune-mass planets". arXiv:1109.2497 [astro-ph].CS1 maint: multiple names: authors list (link)


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