HD 215497
Encyclopedia
HD 215497 is a 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...

 located approximately 142 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 Tucana
Tucana
Tucana is a constellation in the southern sky, created in the late sixteenth century. Its name is Latin for the toucan, a South American bird.-History:...

. It is a K3V star with the characteristics very similar to the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

. In 2009, two 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...

s were discovered orbiting the star.

Planetary system

Announced in 2009, two 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...

s were discovered to be orbiting the star. Both planets are less massive than Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

. The inner planet HD 215497 b
HD 215497 b
HD 215497 b is an extrasolar planet which orbits the K-type main sequence star HD 215497, located approximately 142 light years away in the constellation Tucana. This planet has at least 6.6 times the mass of Earth. This planet was detected by HARPS on October 19, 2009, together with 29 other...

 orbits very close to the star and is termed a “hot super-Earth
Super-Earth
A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below the mass of the Solar System's gas giants. The term super-Earth refers only to the mass of the planet, and does not imply anything about the surface conditions or habitability...

”. The outer planet HD 215497 c
HD 215497 c
HD 215497 c is an extrasolar planet which orbits the G-type main sequence star HD 215497, located approximately 142 light years away in the constellation Tucana. This planet has at least one-thirds the mass of Jupiter and takes 568 days to orbit the star at a semimajor axis of 1.282 AU...

 is Saturn-sized and orbits a little bit further from the star as the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

, at around 1.282 AU.
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