HD 187123 c
Encyclopedia
HD 187123 c is an extrasolar planet
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...

 located approximately 156 light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...

s away in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....

 of Cygnus
Cygnus (constellation)
Cygnus is a northern constellation lying on the plane of the Milky Way. Its name is the Latinized Hellenic word for swan. One of the most recognizable constellations of the northern summer and autumn, it features a prominent asterism known as the Northern Cross...

, orbiting the star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...

 HD 187123
HD 187123
HD 187123 is an 8th magnitude G-type main sequence star located approximately 156 light-years away in the constellation of Cygnus. Like our Sun, it is a yellow dwarf . Being at a distance of about 160 light-years it is not visible to the unaided eye...

. This planet was discovered in 1998 and published in 2006. The radius of the planet's orbit is 4.80 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

, 113 times more distant from the star than first companion. This takes 10 years to orbit. As it is typical for very long-period planets, the orbit is eccentric, referring to as "eccentric Jupiter
Eccentric Jupiter
An eccentric Jupiter is a Jovian planet that orbits its star in an eccentric orbit. Eccentric Jupiters may disqualify a planetary system from having Earth-like planets in it because a massive gas giant with an eccentric orbit may remove all Earth mass planets from the habitable zone.To date, it...

". At periastron, the orbital distance is 3.60 AU and at apastron, the distance is 6.00 AU. The planet's mass is nearly 2 times that of Jupiter, but is likely to be smaller in size than the inner planet.
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