Epoch J2000.0 Equinox J2000.0
|Gliese 86 A|
|Right ascension||02h 10m 25.93s|
|Declination||−50° 49′ 25.4″|
|Apparent magnitude (V)||6.17|
|Gliese 86 B|
|Right ascension||02h 10m 26s|
|Declination||−50° 49′ 25″|
|Apparent magnitude (V)|
|Spectral type||K1V / D?|
|U−B color index||0.45|
|B−V color index||0.812|
|V−R color index||0.45|
|R−I color index||0.40|
|Proper motion (μ)||RA: 2092.86 ± 0.27 mas/yr
Dec.: 653.21 ± 0.30 mas/yr
|Parallax (π)||92.74 ± 0.32 mas|
|Distance||35.2 ± 0.1 ly
(10.78 ± 0.04 pc)
|Radius||0.855 ± 0.005 R☉|
|Luminosity (bolometric)||0.47[note 1] L☉|
|Metallicity||[Fe/H] = -0.24|
|Age||2.4 × 109 years|
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.
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. It was discovered in 2001 and initially suspected to be a brown dwarf, 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. 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.
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. 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. It was discovered by the Swiss 1.2 m Leonhard Euler Telescope operated by the Geneva Observatory.
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.
(in order from star)
|b||>3.91 ± 0.32 MJ||0.1130 ± 0.0065||15.76491 ± 0.00039||0.0416 ± 0.0072||—||—|
- From , where is the luminosity, is the radius, is the effective surface temperature and is the Stefan–Boltzmann constant
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