HD 20781

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HD 20781
Observation data Epoch J2000.0 Equinox J2000.0
Constellation	Fornax
Right ascension	03 20 02.943
Declination	–28° 47′ 01.80″
Apparent magnitude (V)	8.44
Characteristics
Spectral type	G9.5V
Astrometry

Proper motion (μ)	RA: 348.97 ± 0.71 mas/yr Dec.: –67.69 ± 0.91 mas/yr
Parallax (π)	28.27 ± 1.08 mas
Distance	115 ± 4 ly (35 ± 1 pc)

Other designations
CD–29°1229, HIP 15526, LTT 1581, SAO 168468

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. 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.

Planetary system

The HD 20781 planetary system
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	—	—

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
^ 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
"HD 20781 -- High proper-motion Star". SIMBAD Astronomical Database. Centre de données astronomiques de Strasbourg. Retrieved 2014-09-10.
^ Properties of planets in binary systems.
Schneider, J. "Notes for star HD 20781 |cite web". The Extrasolar Planets Encyclopaedia. Retrieved 2011-09-12.
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 .{{cite arXiv}}: CS1 maint: multiple names: authors list (link)
Schneider, J. "Notes for star HD 20781". The Extrasolar Planets Encyclopaedia. Retrieved 2011-09-12.

v t e The HD 20781/HD 20782 system
HD 20781 b c d e
HD 20782 b
See also: binary stars extrasolar planets

Bayer	α (Dalim) β γ γ δ ε ζ η η η ι ι κ λ λ μ ν π ρ σ τ υ φ χ χ χ ψ ω
Variable	R TZ UZ
HR	683 858
HD	15337 20781 20782 20868 (Intan)
Other	2MASS J02431371−2453298 HIP 13044 LP 944-20 UDF 2457 WASP-72 (Diya)

Exoplanets	HD 16417 b HD 20781 b c d e HD 20782 b HD 20868 b (Baiduri) TOI-849 b

Star clusters	NGC 1049

Nebulae	NGC 1360

NGC	823 824 922 986 1097 1210 1255 1288 1310 1316 1317 1318 1326 1350 1365 1374 1375 1379 1380 1381 1387 1398 1399 1406 1425 1427
Other	Fornax Dwarf HUDF-JD2 GS-NDG-9422 IC 335 IC 1993 JADES-GS-z14-0 JADES-GS-z7-01-QU MRC 0316-257 PGC 13809 UDF 423 UDFj-39546284 UDFy-38135539

Galaxy clusters	Fornax Cluster

Astronomical events	SN 1992bd SN 1999eu SN 2003B