Gliese 86

A nearby binary star system, in the southern constellation of Eridanus, in which has been found an extrasolar planet of the epistellar jovian type. The separation of the two stars is about 10 astronomical units (1.5 billion km) or about 100 times that between the planet and the star it revolves around. The planet's host star is a bright, rather cool dwarf, somewhat less massive and luminous than the Sun, just at the limit of naked-eye visibility.

Contrary to most stars with known planetary companions, Gliese 86 contains less metals than the Sun, by a factor of two. The observed characteristics of the planet together with the binary nature of Gliese 86 support the idea that planetary systems may form in ways other than the standard agglomeration scheme (see planetary systems, formation).

Host star
Distance	35 light-years (10.7 pc)
Spectral type	K0 V
Temperature	4,980°C (5,250 K)
Mass (Sun=1)	0.79
Luminosity (Sun=1)	0.45
Apparent magnitude	6.12

Planet
Mass (Jupiter=1)	3.6
Semi-major axis	0.11 AU (16.5 million km, 10.2 million mi.)
Orbital period	15.83 days
Eccentricity	0.045
Inferred surface temperature	380°C (730°F)
Year of discovery	1998
Discoverers	Mayor et al (Geneva), 1.2-m tel. at La Silla
Method of discovery	radial velocity

Related categories

• NOTABLE STARS
• EXTRASOLAR PLANETS AND SUBSTELLAR OBJECTS

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