Kepler-4b, initially known as KOI 7.01, is an

extrasolar planet An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first detect ...

first detected as a

transit Transit may refer to: Arts and entertainment Film * ''Transit'' (1980 film), a 1980 Israeli film * ''Transit'' (1986 film), a Canadian short film * ''Transit'' (2005 film), a film produced by MTV and Staying-Alive about four people in countrie ...

by the Kepler spacecraft. Its

radius In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...

and

mass Mass is an Intrinsic and extrinsic properties, intrinsic property of a physical body, body. It was traditionally believed to be related to the physical quantity, quantity of matter in a body, until the discovery of the atom and particle physi ...

are similar to that of

Neptune Neptune is the eighth and farthest known planet from the Sun. It is the List of Solar System objects by size, fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 t ...

; however, due to its proximity to its host star, it is substantially hotter than any planet in the Solar System. The planet's discovery was announced on January 4, 2010, in

Washington, D.C. Washington, D.C., formally the District of Columbia and commonly known as Washington or D.C., is the capital city and federal district of the United States. The city is on the Potomac River, across from Virginia, and shares land borders with ...

, along with four other planets that were initially detected by the Kepler spacecraft and subsequently confirmed by telescopes at the

W.M. Keck Observatory The W. M. Keck Observatory is an astronomical observatory with two telescopes at an elevation of 4,145 meters (13,600 ft) near the summit of Mauna Kea in the U.S. state of Hawaii. Both telescopes have aperture primary mirrors, and, when c ...

Nomenclature and history

Kepler-4b was named because it was the first planet discovered in the orbit of its star,

Kepler-4 Kepler-4 is a sunlike star located about 1626 light-years away in the constellation Draco (constellation), Draco. It is in the field of view of the Kepler Mission, a NASA operation purposed with finding terrestrial planet, Earth-like plane ...

. The star was, in turn, named for the Kepler Mission, a

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

satellite whose purpose is to discover Earth-like planets in a section of the sky between constellations Cygnus and

Lyra , from ; pronounced: ) is a small constellation. It is one of the 48 listed by the 2nd century astronomer Ptolemy, and is one of the modern 88 constellations recognized by the International Astronomical Union. Lyra was often represented on star ...

using the transit method. Using this method, Kepler notes small and steady decreases in a star's brightness that are measured as a planet crosses in front of it. Initially, Kepler-4b was detected as a transit event by the

Kepler telescope The Kepler space telescope is a defunct 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 orb ...

and considered a Kepler Object of Interest with the designation KOI 7.01. Subsequent

radial velocity The radial velocity or line-of-sight velocity of a target with respect to an observer is the rate of change of the vector displacement between the two points. It is formulated as the vector projection of the target-observer relative velocity ...

measurements by the High Resolution Echelle Spectrometer on the telescopes of W.M. Keck Observatory confirmed the planetary nature of the transit event and established a mass estimate for the planet. The planet's discovery was announced on January 4, 2010, along with four other planets detected by Kepler: Kepler-5b, 6b, 7b and 8b 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.

Host star

is a star very similar to the sun located about 1610 light-years away from Earth, 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 first constellati ...

of Draco.

Characteristics

Kepler-4b orbits its host star in 3.213 days at a distance of 0.046 AU. This places it almost 10 times closer to its star than Mercury is to the Sun. Consequently, Kepler-4b is thought to be extremely hot, with an

equilibrium temperature The planetary equilibrium temperature is a theoretical temperature that a planet would be if it were in radiative equilibrium, typically under the assumption that it radiates as a black body being heated only by its parent star. In this model, th ...

greater than 1700

kelvin The kelvin (symbol: K) is the base unit for temperature in the International System of Units (SI). The Kelvin scale is an absolute temperature scale that starts at the lowest possible temperature (absolute zero), taken to be 0 K. By de ...

s (2600 °F). (1426°C) The planet is estimated to be 25 times more massive than the Earth with a radius that is 4 times greater than the Earth. This makes it similar to Neptune in terms of size and mass, but with a temperature that is not comparable to any planet in the Solar System (Venus, the hottest planet, is only 735 kelvins). Kepler-4b's

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-Centre (geometry), center, in geometry * Eccentricity (g ...

was assumed to be 0, however an independent reanalysis of the discovery data found a value of 0.25 ± 0.12, and a later reanalysis of the light curve discovered a secondary eclipse with depth 7.47 ± 1.82ppm at a phase of about 0.7. Kepler first five exoplanet size

References

External links

NASA.gov
{{DEFAULTSORT:Kepler-4b Exoplanets with Kepler designations Exoplanets discovered in 2010 Kepler-04b Giant planets Transiting exoplanets Draco (constellation) 4b

Nomenclature and history

Host star

Characteristics

See also

References

External links