Gliese 86

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Gliese 86
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Eridanus
Gliese 86 A
Right ascension 02h 10m 25.93425s[1]
Declination −50° 49′ 25.4179″[1]
Apparent magnitude (V) 6.17[2]
Gliese 86 B
Right ascension 02h 10m 26s
Declination −50° 49′ 25″
Apparent magnitude (V)
Spectral type K1V[3] + D?[4]
U−B color index 0.45
B−V color index 0.812[1]
V−R color index 0.45
R−I color index 0.40
Radial velocity (Rv) 56.7[5] km/s
Proper motion (μ) RA: 2092.86 ± 0.27[1] mas/yr
Dec.: 653.21 ± 0.30[1] mas/yr
Parallax (π) 92.74 ± 0.32[1] mas
Distance 35.2 ± 0.1 ly
(10.78 ± 0.04 pc)
Absolute magnitude (MV) 5.95[6]
Gliese 86 A
Mass 0.797[5] M
Radius 0.855 ± 0.005 R
Luminosity (bolometric) 0.47[note 1] L
Surface gravity (log g) 4.51[3] cgs
Temperature 5,217[5] K
Metallicity [Fe/H] −0.23[5] dex
Rotation 31 days
Age 2.4[7] Gyr
Other designations
13 G. Eridani, GJ 86, HD 13445, HIP 10138, HR 637, SAO 232658
Database references
Exoplanet Archive data
Extrasolar Planets

Gliese 86 (13 G. Eridani) is a K-type main-sequence star approximately 35 light-years away in the constellation of Eridanus. It has been confirmed that a white dwarf orbits the primary star. In 1998 the European Southern Observatory announced that an extrasolar planet was orbiting the star.[8]

Stellar components[edit]

The primary companion (Gliese 86 A) is a K-type main-sequence star of spectral type K1V. The characteristics in comparison to our Sun are 79% the mass, 86% the radius, and 50% the luminosity. The star has a close-orbiting massive Jovian planet.

Gliese 86 B is a white dwarf located around 21 AU from the primary star, making the Gliese 86 system one of the tightest binaries known to host an extrasolar planet.[9] It was discovered in 2001 and initially suspected to be a brown dwarf,[10] but high contrast observations in 2005 suggested that the object is probably a white dwarf, as its spectrum does not exhibit molecular absorption features which are typical of brown dwarfs.[4] Assuming the white dwarf has a mass about half that of our Sun and that the linear trend observed in radial velocity measurements is due to Gliese 86 B, a plausible orbit for this star around Gliese 86 A has a semimajor axis of 18.42 AU and an eccentricity of 0.3974.[11]

Planetary system[edit]

The preliminary astrometric measurements made with the Hipparcos space probe suggest the planet has an orbital inclination of 164.0° and a mass 15 times Jupiter, which would make the object a brown dwarf.[12] However, further analysis suggests the Hipparcos measurements are not precise enough to reliably determine astrometric orbits of substellar companions, thus the orbital inclination and true mass of the candidate planet remain unknown.[13] It was discovered by the Swiss 1.2 m Leonhard Euler Telescope operated by the Geneva Observatory.[14]

The radial velocity measurements of Gliese 86 show a linear trend once the motion due to this planet are taken out. This may be associated with the orbital motion of the white dwarf companion.

The Gliese 86 planetary system[15]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b >3.91 ± 0.32 MJ 0.1130 ± 0.0065 15.76491 ± 0.00039 0.0416 ± 0.0072

See also[edit]


  1. ^ From , where is the luminosity, is the radius, is the effective surface temperature and is the Stefan–Boltzmann constant


  1. ^ a b c d e f van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. Bibcode:2007A&A...474..653V. arXiv:0708.1752Freely accessible. doi:10.1051/0004-6361:20078357.  Vizier catalog entry
  2. ^ C. Cincunegui; P. J. D. Mauas (2004). "Library of flux-calibrated echelle spectra of southern late-type dwarfs with different activity levels". Astronomy and Astrophysics. 414 (2): 699–706. Bibcode:2004A&A...414..699C. doi:10.1051/0004-6361:20031671. 
  3. ^ a b Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, Bibcode:2006AJ....132..161G, arXiv:astro-ph/0603770Freely accessible, doi:10.1086/504637. 
  4. ^ a b Mugrauer, M.; Neuhäuser, R. (2005). "Gl86B: a white dwarf orbits an exoplanet host star". Monthly Notices of the Royal Astronomical Society: Letters. 361 (1): L15–L19. Bibcode:2005MNRAS.361L..15M. arXiv:astro-ph/0506311Freely accessible. doi:10.1111/j.1745-3933.2005.00055.x. 
  5. ^ a b c d Ramírez, I.; et al. (February 2013), "Oxygen abundances in nearby FGK stars and the galactic chemical evolution of the local disk and halo", The Astrophysical Journal, 764 (1): 78, Bibcode:2013ApJ...764...78R, arXiv:1301.1582Freely accessible, doi:10.1088/0004-637X/764/1/78. 
  6. ^ Holmberg, J.; et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, Bibcode:2009A&A...501..941H, arXiv:0811.3982Freely accessible, doi:10.1051/0004-6361/200811191. 
  7. ^ Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008). "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics". The Astrophysical Journal. 687 (2): 1264–1293. Bibcode:2008ApJ...687.1264M. arXiv:0807.1686Freely accessible. doi:10.1086/591785. 
  8. ^ "Extrasolar Planet in Double Star System Discovered from La Silla" (Press release). Garching, Germany: European Southern Observatory. November 24, 1998. Retrieved December 29, 2012. 
  9. ^ Raghavan; Henry, Todd J.; Mason, Brian D.; Subasavage, John P.; Jao, Wei‐Chun; Beaulieu, Thom D.; Hambly, Nigel C. (2006). "Two Suns in The Sky: Stellar Multiplicity in Exoplanet Systems". The Astrophysical Journal. 646 (1): 523–542. Bibcode:2006ApJ...646..523R. arXiv:astro-ph/0603836Freely accessible. doi:10.1086/504823. 
  10. ^ Els, S. G.; et al. (2001). "A second substellar companion in the Gliese 86 system. A brown dwarf in an extrasolar planetary system". Astronomy and Astrophysics. 370 (1): L1–L4. Bibcode:2001A&A...370L...1E. doi:10.1051/0004-6361:20010298. 
  11. ^ Lagrange, A.-M.; et al. (2006). "New constrains on Gliese 86 B. VLT near infrared coronographic imaging survey of planetary hosts". Astronomy and Astrophysics. 459 (3): 955–963. Bibcode:2006A&A...459..955L. doi:10.1051/0004-6361:20054710. 
  12. ^ Han; Black, David C.; Gatewood, George (2001). "Preliminary astrometric masses for proposed extrasolar planetary companions". The Astrophysical Journal Letters. 548 (1): L57–L60. Bibcode:2001ApJ...548L..57H. doi:10.1086/318927. 
  13. ^ Pourbaix, D.; Arenou, F. (2001). "Screening the Hipparcos-based astrometric orbits of sub-stellar objects". Astronomy and Astrophysics. 372 (3): 935–944. Bibcode:2001A&A...372..935P. arXiv:astro-ph/0104412Freely accessible. doi:10.1051/0004-6361:20010597. 
  14. ^
  15. ^ Butler, R. P.; et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal. 646 (1): 505–522. Bibcode:2006ApJ...646..505B. arXiv:astro-ph/0607493Freely accessible. doi:10.1086/504701. 

External links[edit]

Coordinates: Sky map 02h 10m 14s, −50° 50′ 00″