Kepler-69 (''KOI-172'', ''2MASS J19330262+4452080'',
KIC 8692861
') is a G-type main-sequence star similar to the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

in the constellation Cygnus, located about from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. On April 18, 2013 it was announced that the star has two planets. Although initial estimates indicated that the terrestrial planet Kepler-69c might be within the star's

habitable zone In astronomy and astrobiology, the circumstellar habitable zone (CHZ), or simply the habitable zone, is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure.J. F. Kast ...

, further analysis showed that the planet very likely is interior to the habitable zone and is far more analogous to Venus than to Earth and thus completely inhospitable.

Nomenclature and history

Prior to Kepler observation, Kepler-69 had the

2MASS The Two Micron All-Sky Survey, or 2MASS, was an astronomical survey of the whole sky in infrared light. It took place between 1997 and 2001, in two different locations: at the U.S. Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona, and ...

catalogue number 2MASS J19330262+4452080. In the Kepler Input Catalog it has the designation of KIC 8692861, and when it was found to have transiting planet candidates it was given the Kepler object of interest number of KOI-172. LombergA1024

The star's planets were discovered by

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...

Kepler Mission The Kepler space telescope is a disused space telescope launched by NASA in 2009 to discover Earth-sized planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched into an Earth-trailing heliocentric orbi ...

, a mission tasked with discovering planets in

transit Transit may refer to: Arts and entertainment Film * ''Transit'' (1979 film), a 1979 Israeli film * ''Transit'' (2005 film), a film produced by MTV and Staying-Alive about four people in countries in the world * ''Transit'' (2006 film), a 2006 ...

around their stars. The transit method that Kepler uses involves detecting dips in brightness in stars. These dips in brightness can be interpreted as planets whose orbits move in front of their stars from the perspective of

. The name Kepler-69 derives directly from the fact that the star is the catalogued 69th star discovered by ''Kepler'' to have confirmed planets. The designations ''b'', ''c'' derive from the order of discovery. The designation of ''b'' is given to the first planet orbiting a given star, followed by the other lowercase letters of the alphabet. In the case of Kepler-69, all of the known planets in the system were discovered at one time, so ''b'' is applied to the closest planet to the star and ''c'' to the farthest.

Stellar characteristics

Kepler-69 is a G4 star that is approximately 81% the mass of and 93% the radius of the

. It has a surface temperature of 5638 ± 168 K and is 9.8 billion years old. In comparison, the Sun has a surface temperature of 5778 K and is 4.6 billion years old. The star's

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...

, or how bright it appears from Earth's perspective, is 13.7. Therefore, Kepler-69 is too dim to be seen with the naked eye.

Planetary system

Kepler-69 has two known planets orbiting around it. Kepler-69b is a hot

super-Earth A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17 times Earth's, respectively. The term "super-Earth" refers only to ...

-sized exoplanet. Kepler-69c is a super-Earth-sized exoplanet, about 70% larger than Earth. It receives a similar amount of flux from its star as Venus does from the Sun, and is thus a likely candidate for a super-Venus.

References

External links

Kepler Mission
–

.
Kepler – Discoveries – Summary Table
–

.
Kepler – Discovery of New Planetary Systems (2013)

– NYT.
Video (02:27) - NASA Finds Three New Planets in "Habitable Zone" (04/18/2013).
{{Sky, 19, 33, 02.62, +, 44, 52, 08.0 G-type main-sequence stars Planetary transit variables Cygnus (constellation) 172 Planetary systems with two confirmed planets

Nomenclature and history

Stellar characteristics

Planetary system

See also

References

External links