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.[5] 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.[5][6] The HD 20781 do not have a noticeable starspot activity.[3]

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) 8.48
Characteristics
Spectral type K0V[3]
B−V color index 0.82
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)
Details[3]
Mass0.7 M☉
Luminosity0.49±0.04 L☉
Surface gravity (log g)4.37±0.05 cgs
Temperature5256±29 K
Metallicity [Fe/H]−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, 2MASS J03200291-2847016, Gaia DR1 5060105892897388288[4]
Database references
SIMBADdata

Planetary system

In 2011, a pair of Neptune-sized gas giants were detected with the radial velocity method. In 2017, an additional two inner super-Earths were suspected, with periods of 5.3 and 13.9 days respectively.[3]

The HD 20781 planetary system[3]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
d (unconfirmed) ≥1.93+0.39
−0.36 M⊕		 0.0529+0.0024
−0.0027		 5.3135±0.0010 0.10+0.11
−0.07		 — —
e (unconfirmed) ≥5.33+0.70
−0.67 M⊕		 0.1004+0.0046
−0.0051		 13.8905+0.0033
−0.0034		 0.09+0.09
−0.06		 — —
b ≥10.61+1.20
−1.19 M⊕		 0.1647+0.0076
−0.0083		 29.1580+0.0102
−0.0100		 0.11+0.05
−0.06		 — —
c ≥14.03±1.56 M⊕ 0.3374+0.0155
−0.0170		 85.5073+0.0983
−0.0947		 0.06+0.06
−0.04		 — —

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. S2CID 18759600.Vizier catalog entry
  3. Udry, S.; Dumusque, X.; Lovis, C.; Segransan, D.; Diaz, R. F.; Benz, W.; Bouchy, F.; Coffinet, A.; Lo Curto, G.; Mayor, M.; Mordasini, C.; Motalebi, F.; Pepe, F.; Queloz, D.; Santos, N. C.; Wyttenbach, A.; Alonso, R.; Collier Cameron, A.; Deleuil, M.; Figueira, P.; Gillon, M.; Moutou, C.; Pollacco, D.; Pompei, E. (2019), "The HARPS search for southern extra-solar planets. XLII. Eight HARPS multi-planet systems hosting 20 super-Earth and Neptune-mass companions", Astronomy & Astrophysics, A37: 622, arXiv:1705.05153, doi:10.1051/0004-6361/201731173, S2CID 119095511
  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 [astro-ph].CS1 maint: multiple names: authors list (link)
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.