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'''HD 20781''' is a star which is part of a wide ] with ]. The companion star has a very large ] of 252 arcsec, corresponding to 9080 AU at the distance of HD 20782.<ref name=Desidera></ref> Both stars possess their own ]s in ]s. This is the first time that ] in both components of a wide binary system.<ref name=Desidera/><ref name=Sch-20781/><ref>{{cite arXiv|eprint=1109.2497|class=astro-ph|title=The HARPS search for southern extra-solar planets XXXIV. Occurrence, mass distribution and orbital properties of super-Earths and Neptune-mass planets|author=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.|date=2011|display-authors=etal}}</ref> '''HD 20781''' is a star which is part of a wide ] with ]. The companion star has a very large ] of 252 arcsec, corresponding to 9080 AU at the distance of HD 20782.<ref name=Desidera></ref> Both stars possess their own ]s in ]s. This is the first time that ] in both components of a wide binary system.<ref name=Desidera/><ref>{{cite arXiv|eprint=1109.2497|class=astro-ph|title=The HARPS search for southern extra-solar planets XXXIV. Occurrence, mass distribution and orbital properties of super-Earths and Neptune-mass planets|author=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.|date=2011|display-authors=etal}}</ref>
The '''HD 20781''' do not have a noticeable ] activity.<ref name=Udry2017/> The '''HD 20781''' do not have a noticeable ] activity.<ref name=Udry2017/>
== Planetary system == == Planetary system ==

Revision as of 01:46, 18 September 2020

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) 8.48
Characteristics
Spectral type K0V
B−V color index 0.82
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
Distance115 ± 4 ly
(35 ± 1 pc)
Details
Mass0.7 M☉
Luminosity0.49±0.04 L☉
Surface gravity (log g)4.37±0.05 cgs
Temperature5256±29 K
Metallicity −0.11±0.02 dex
Rotation46.8±4.4 d
Rotational velocity (v sin i)1.1 km/s
Other designations
CD–29° 1229, HIP 15526, LTT 1581, SAO 168468
Database references
SIMBADdata

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. The HD 20781 do not have a noticeable starspot activity.

Planetary system

In 2011, a pair of small gas giants was detected by radial velocity method. As is 2017, additional two inner rocky planets are suspected, with periods 5.3 and 13.9 days respectively.

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 — —

See also

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. ^ The HARPS search for southern extra-solar planets. XLII. Eight HARPS multi-planet systems hosting 20 super-Earth and Neptune-mass companions, 2017, arXiv:1705.05153
  4. "HD 20781 -- High proper-motion Star". SIMBAD Astronomical Database. Centre de données astronomiques de Strasbourg. Retrieved 2014-09-10.
  5. ^ Properties of planets in binary systems.
  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 .{{cite arXiv}}: CS1 maint: multiple names: authors list (link)

External links

The HD 20781/HD 20782 system
HD 20781
  • HD 20782
  • b


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