Astronomy:HD 20781
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Short description: Star in a binary star system in the constellation Fornax
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| 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[2] mas/yr Dec.: −66.614±0.019[2] mas/yr |
| Parallax (π) | 27.8123 ± 0.0239[2] mas |
| 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 | |
| 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]
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]
| 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±0.0010 | 0.10+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
- 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. doi:10.1086/132034. Bibcode: 1987PASP...99..695R. Vizier query form
- ↑ 2.0 2.1 2.2 2.3 2.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 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. doi:10.1051/0004-6361/201731173. Bibcode: 2019A&A...622A..37U.
- ↑ "HD 20781 -- High proper-motion Star". Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD+20781.
- ↑ 5.0 5.1 Desidera, S.; Barbieri, M. (January 2007). "Properties of planets in binary systems. The role of binary separation". Astronomy and Astrophysics 462 (1): 345–353. doi:10.1051/0004-6361:20066319. Bibcode: 2007A&A...462..345D.
- ↑ "HD 20782". https://exoplanetarchive.ipac.caltech.edu/overview/HD%2020781.
- ↑ 7.0 7.1 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].
External links
- "Planet HD 20781 c". Extrasolar Planets Encyclopaedia. https://exoplanet.eu/catalog/hd_20781_c--946/. Retrieved 18 September 2020.
- "Planet HD 20781 b". Extrasolar Planets Encyclopaedia. https://exoplanet.eu/catalog/hd_20781_b--945/. Retrieved 18 September 2020.
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