Kepler-421b is an
exoplanet
An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...
that, as of July 2014, has the longest known
year
A year or annus is the orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the hou ...
of any
transiting planet
In astronomy, a transit (or astronomical transit) is a phenomenon when a celestial body passes directly between a larger body and the observer. As viewed from a particular vantage point, the transiting body appears to move across the face of th ...
(704 days),
although not as long as the planets that have been
directly imaged, or many of the planets found by the
radial-velocity method
Doppler spectroscopy (also known as the radial-velocity method, or colloquially, the wobble method) is an indirect method for finding extrasolar planets and brown dwarfs from radial-velocity measurements via observation of Doppler shifts in t ...
, or as long as some transiting planet candidates which are listed as planets in the
Extrasolar Planets Encyclopaedia (KIC 5010054 b etc.).
It is the first transiting-planet found near the
snow-line
The climatic snow line is the boundary between a snow-covered and snow-free surface. The actual snow line may adjust seasonally, and be either significantly higher in elevation, or lower. The permanent snow line is the level above which snow wil ...
.
Normally, at least three transits are required to confirm a planet. Due to very high signal to noise ratio, only two transits were sufficient to validate Kepler-421b to be a real planet without additional confirmation methods.
Kepler-421b is slightly larger than Uranus although its mass is not known.
References
Further reading
The Longest Year Phil Plait, Slate, July 23, 2014
New Exoplanet Has the Longest Year Ever Discovered July 23, 2014 at 2:15:00 PM by Niko Vercelletto, Popular Mechanics
Astronomers discover exoplanet with longest known year Anthony Wood, July 23, 2014, Gizmag
First Exoplanet Discovered Beyond the “Snow Line” by Shannon Hall on July 22, 2014, Universe Today
Transiting Exoplanet With Longest Known Year Discovered By Kepler Mission, July 22, 2014, RedOrbit
Discovery of a Transiting Planet Near the Snow-Line David M. Kipping, Guillermo Torres, Lars A. Buchhave, Scott J. Kenyon, Christopher E. Henze, Howard Isaacson, Rea Kolbl, Geoff W. Marcy, Stephen T. Bryson, Keivan G. Stassun, Fabienne A. Bastien, (Submitted on 17 Jul 2014)
Exoplanets discovered in 2014
Transiting exoplanets
421b
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