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| 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 |
| Distance | 115 ± 4 ly (35 ± 1 pc) |
| Details | |
| Mass | 0.7 M☉ |
| Luminosity | 0.49±0.04 L☉ |
| Surface gravity (log g) | 4.37±0.05 cgs |
| Temperature | 5256±29 K |
| Metallicity | −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 | |
| 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. 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. HD 20781 has no noticeable starspot activity.
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.
| 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
- 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. S2CID 18759600.Vizier catalog entry
- ^ 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, Bibcode:2019A&A...622A..37U, doi:10.1051/0004-6361/201731173, S2CID 119095511
- "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.
- 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
- "Planet HD 20781 c". The Extrasolar Planets Encyclopaedia. Retrieved 18 September 2020.
- "Planet HD 20781 b". The Extrasolar Planets Encyclopaedia. Retrieved 18 September 2020.
| The HD 20781/HD 20782 system | |
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| HD 20781 | |
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