Kepler-8 is a

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

located in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Lyra in the field of view of the Kepler Mission, a NASA-led operation tasked with discovering terrestrial planets. The star, which is slightly hotter, larger, and more massive than the Sun, has one gas giant in its orbit,

Kepler-8b Kepler-8b is the fifth of the first five exoplanets discovered by NASA's Kepler (satellite), Kepler spacecraft, which aims to discover planets in a region of the sky between the constellations Lyra (constellation), Lyra and Cygnus (constellation) ...

. This gas giant is larger than Jupiter, but is less massive, and thus more diffuse. The planet's discovery was announced to the public on January 4, 2010 along with four other planets. As the fifth confirmed planetary system verified by Kepler, it helped demonstrate the capabilities of the Kepler spacecraft.

Nomenclature and history

Kepler-8 was named the way it was because it is home to the eighth planetary system confirmed during the course of the Kepler Mission, a NASA-directed program tasked with searching a region of the sky for terrestrial planets that transit, or cross in front of (and thereby, for a while, make dimmer) the stars that they orbit with respect to Earth. The planet in orbit around Kepler-8, Kepler-8b, was the fifth of the first five planets discovered by the Kepler spacecraft; the first three planets confirmed by Kepler had been previously discovered, and were only used to verify the accuracy of Kepler's measurements. Kepler-8b's discovery was announced to the public on January 4, 2010 at the 215th meeting of the

American Astronomical Society The American Astronomical Society (AAS, sometimes spoken as "double-A-S") is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC. The primary objective of the AAS is to promote the adv ...

in Washington, D.C., alongside planets in orbit around Kepler-4, Kepler-5,

Kepler-6 Kepler-6 is a G-type star situated in the constellation Cygnus. The star lies within the field of view of the Kepler Mission, which discovered it as part of a NASA-led mission to discover Earth-like planets. The star, which is slightly ...

, and Kepler-7. The data that was used to identify Kepler-8b's existence was re-examined and verified by observatories in Hawaii, Arizona, Texas, California, and the Canary Islands.

Characteristics

Kepler-8 is situated some 1050 pc (or

light year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s) from Earth. With a mass of 1.213 M_sun and a radius of 1.486 R_sun, Kepler-8 is more massive than the Sun by about a fifth of the Sun's mass, and is nearly three halves its size. The star is predicted to be 3.84 (± 1.5) billion years old, compared to the Sun's age at 4.6 billion years. Kepler-8 has a

metallicity In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal physical matter in the Universe is either hydrogen or helium, and astronomers use the word ''"metals"'' as a ...

of e/H= -0.055 (± 0.03), making it 12% less metal-rich than the metal-rich Sun; metallicity is important in stars because stars richer in metal are more likely to harbor planets. The star also has an

effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...

of 6213 (± 150) K, meaning that it is hotter than the Sun, which has an effective temperature of 5778 K. Kepler first five exoplanet size

Kepler-8 has an apparent magnitude of 13.9; in other words, as seen from Earth, Kepler-8 is an extremely dim star. It cannot be seen with the naked eye.

Planetary system

is the only planet that has been discovered orbiting of Kepler-8. With a mass of .603 M_J and a radius of 1.419 R_J, the planet is 60% the mass of, but 42% larger than planet Jupiter. The planet is diffuse, with a density of .261 grams/cc, especially in comparison to Jupiter and its density of 5.515 grams/cc. At a distance of .0483 AU, Kepler-8b orbits its star every 3.5225 days. The eccentricity of Kepler-8 is assumed to be 0, which would give the planet a circular orbit. In comparison, planet

Mercury Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Merc ...

orbits the Sun at .3871 AU every 87.97 days. Mercury also has an elliptical orbit, with an eccentricity of .2056.

References

{{Stars of Lyra Planetary systems with one confirmed planet Lyra (constellation) 10 Planetary transit variables F-type main-sequence stars

Nomenclature and history

Characteristics

Planetary system

See also

References