HD 20781

Last updated
HD 20781
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Fornax [1]
Right ascension 03h 20m 02.94286s [2]
Declination −28° 47′ 01.7905″ [2]
Apparent magnitude  (V)8.48 [3]
Characteristics
Spectral type K0V [3]
B−V color index 0.82 [3]
Astrometry
Radial velocity (Rv)40.27±0.12 [2] km/s
Proper motion (μ)RA: 348.869±0.015 mas/yr [2]
Dec.: −66.614±0.019 mas/yr [2]
Parallax (π)27.8123±0.0239  mas [2]
Distance 117.3 ± 0.1  ly
(35.96 ± 0.03  pc)
Absolute magnitude  (MV)5.70 [3]
Details [3]
Mass 0.7  M☉
Luminosity 0.49±0.04  L☉
Surface gravity (log g)4.37±0.05  cgs
Temperature 5256±29  K
Metallicity [Fe/H]−0.11±0.02  dex
Rotation 46.8±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
SIMBAD data

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, with a total of five known planets around both stars. [3] [6] This is the first known example of planets being found orbiting both components of a wide binary system. [5] [7] HD 20781 has no noticeable starspot activity. [3]

Contents

Planetary system

In 2011, a pair of Neptune-mass gas giants were detected with the radial velocity method. [7] In 2017, these planets were confirmed and an additional two inner super-Earths were detected, 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
b ≥1.93+0.39
−0.36  M🜨 		0.0529+0.0024
−0.0027		5.3135±0.00100.10+0.11
−0.07		——
c ≥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		——
d ≥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		——
e ≥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

Other systems with multiple planet-hosting stars:

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. 1 2 3 4 5 6 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  3. 1 2 3 4 5 6 7 8 9 Udry, S.; Dumusque, X.; et al. (February 2019). "The HARPS search for southern extra-solar planets. XLIV. Eight HARPS multi-planet systems hosting 20 super-Earth and Neptune-mass companions". Astronomy & Astrophysics . 622: A37. arXiv: 1705.05153 . Bibcode:2019A&A...622A..37U. 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. 1 2 Desidera, S.; Barbieri, M. (January 2007). "Properties of planets in binary systems. The role of binary separation". Astronomy and Astrophysics . 462 (1): 345–353. arXiv: astro-ph/0610623 . Bibcode:2007A&A...462..345D. doi:10.1051/0004-6361:20066319. S2CID   13813761.
  6. ↑ "HD 20782". NASA Exoplanet Archive . Retrieved 12 November 2022.
  7. 1 2 Mayor, M.; Marmier, M.; 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].
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