Gliese 777

An extrasolar planet orbits the primary component in a very long orbit.

Gliese 777 A

Gliese 777 A is a yellow subgiant, a Sun-like star that is ceasing fusing hydrogen in its core. The star is much older than the Sun being about 6700 million years old. It is 4% less massive than the Sun. It is also rather metal-rich having about 70% more "metals" (elements heavier than helium) than the Sun, which is typical to stars with extrasolar planets.

Gliese 777 Ab

Gliese 777 Ab is a planet orbiting star Gliese 777 A. It was discovered in 2002 by the Geneva Extrasolar Planet Search Team using the radial velocity method that has been used to detect most of the planets found so far. The planet is at least one third more massive than Jupiter. Because the inclination of the planet's orbit is not known, the true mass is unknown. But it is unlikely to be much more than the given minimum mass.

The planet has one of the longest orbits currently known for an extrasolar planet. The planet's mean distance from the star is comparable to the distance between Jupiter and the Sun. However, unlike Jupiter it has a very eccentric orbit. At periastron the distance between the planet and the star is only 2.50 AU and at apoastron the distance is as much as 7.10 AU (compared to our Solar system, distance from Sun to the inner asteroid belt and from Sun to between the orbits of Jupiter and Saturn). The gravitational influence of the red dwarf companion may have caused the great eccentricity of the planet.

The signal produced by the planet is very weak and the parameters given are rather vague. Originally the eccentricity was "fixed" to 0 which led to misinformed speculations of very Jupiter-like planet with a circular orbit. Fortunately, the inner system should be stable for Earth-like planets.

Gliese 777 B

Gliese 777 B is a distant, dim red dwarf star orbiting the primary at a distance of 3000 AU. One orbit takes at least tens of thousands of years to complete.

Not much information is available on the star.

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