HD 20782

HD 20782
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Fornax
Right ascension 03h 20m 03.5776s
Declination –28° 51′ 14.656″
Apparent magnitude (V) 7.38
Absolute magnitude (V)4.60
Distance117 ly
(36 pc)
Spectral typeG3V
Other designations
CD-29°1231, HIP 15527, LTT 1582, SAO 168469
Database references
SIMBADdata

HD 20782 is a 7th magnitude G-type main sequence star about 117 light-years away from Earth, in the constellation of Fornax. HD 20782 is a part of a wide binary system in which the other star is designated HD 20781, and both stars host planetary systems. Indeed this is the first known case of a binary star system where there are planetary systems around both the primary and the secondary stars in the system. The companion star HD 20781 has a very large angular separation of 252 arcsec, corresponding to 9080 AU at the distance of HD 20782.[1] It is estimated to be 7.1 (± 4) billion years old, with a mass close to that of our Sun. (Note that, despite the numbering, HD 20782 is the primary star of the system, and HD 20781 the secondary star.)

An extremely eccentric extrasolar planet was announced around HD 20782 in 2006.[2][3] In 2009 this planet's orbit was narrowed down, and it was found to have the highest eccentricity of all known exoplanets; this distinction has stood since 2012.

And in 2011 two also-eccentric (but less so) Neptune-mass planets were announced around the HD 20781.[4][5]

Planetary systems

HD 20782

The HD 20782 planetary system[2]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 1.80 ± 0.23 MJ 1.36 ± 0.12 585.86 ± 0.03 0.97 ± 0.01[6] — —

HD 20781

The HD 20781 planetary system[7]
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 — —

See also

References

  1. ↑ http://www.aanda.org/index.php?option=com_article&access=bibcode&Itemid=129&bibcode=2007A%2526A...462..345DFUL
  2. 1 2 Jones; et al. (2006). "High-eccentricity planets from the Anglo-Australian Planet Search" (abstract). Monthly Notices of the Royal Astronomical Society 369: 249–256. arXiv:astro-ph/0603335. Bibcode:2006MNRAS.369..249J. doi:10.1111/j.1365-2966.2006.10298.x. (web preprint)
  3. ↑ Schneider, J. "Notes for HD 20782 |cite web". The Extrasolar Planets Encyclopaedia.
  4. ↑ Schneider, J. "Notes for star HD 20781 |cite web". The Extrasolar Planets Encyclopaedia. Retrieved 2011-09-12.
  5. ↑ 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].
  6. ↑ S. J. O'Toole, C. G. Tinney, H. R. A. Jones, R. P. Butler, G. W. Marcy, B. Carter, J. Bailey (2009). "Selection Functions in Doppler Planet Searches". MNRAS. 392, 641. arXiv:0810.1589. Bibcode:2009MNRAS.392..641O. doi:10.1111/j.1365-2966.2008.14051.x.
  7. ↑ Schneider, J. "Notes for star HD 20781". The Extrasolar Planets Encyclopaedia. Retrieved 2011-09-12.

External links

Coordinates: 03h 20m 03.5776s, −28° 51′ 14.656″


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