Kepler-4b, initially known as KOI 7.01, is an extrasolar planet first detected as a transit by the

Kepler spacecraft 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 orb ...

. Its radius and mass are similar to that of

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

; 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., 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 comp ...

Nomenclature and history

Kepler-4b was named because it was the first planet discovered in the orbit of its star, Kepler-4. The star was, in turn, named for the Kepler Mission, a NASA satellite whose purpose is to discover Earth-like planets in a section of the sky between constellations Cygnus and Lyra 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 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 orbit ...

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

radial velocity The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the temporal rate of change, rate of change of the distance or Slant range, range between the two points. It is e ...

measurements by the

High Resolution Echelle Spectrometer 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 comp ...

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 __NOTOC__ Kepler-5b is one of the first five planets discovered by NASA's Kepler spacecraft. It is a Hot Jupiter that orbits a subgiant star that is more massive, larger, and more diffuse than the Sun is. Kepler-5 was first flagged as the locatio ...

, 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

Kepler-4 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 origins of the e ...

Draco Draco is the Latin word for serpent or dragon. Draco or Drako may also refer to: People * Draco (lawgiver) (from Greek: Δράκων; 7th century BC), the first lawgiver of ancient Athens, Greece, from whom the term ''draconian'' is derived * D ...

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 greater than 1700 kelvins (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 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

Other Kepler Planets

* Kepler-6b * Kepler-7b *

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) ...

Kepler-9b __NOTOC__ Kepler-9b is one of the first planets discovered outside the solar system (exoplanets) by NASA's Kepler Mission. It revolves around the star Kepler-9 within the constellation Lyra. Kepler-9b is the largest of three planets detected in ...

Kepler-9c Kepler-9c is one of the first seven extrasolar planets, exoplanets, discovered by NASA's Kepler Mission, and one of at least two planets orbiting the star Kepler-9. Kepler-9c and Kepler-9b were the first exoplanets confirmed to be transiting thei ...

* Kepler-9d *

Kepler-10b Kepler-10b is the first confirmed terrestrial planet to have been discovered outside the Solar System by the Kepler Space Telescope. Discovered after several months of data collection during the course of the NASA-directed Kepler Mission, which ...

Kepler-10c Kepler-10c is an exoplanet orbiting the G-type star Kepler-10, located around 608 light-years away in Draco. Its discovery was announced by Kepler in May 2011, although it had been seen as a planetary candidate since January 2011, when Kepler-1 ...

* Kepler-10d (Unknown) * Kepler-11b * Kepler-11c * Kepler-11d * Kepler-11e *

Kepler-11f Kepler-11f is an exoplanet (extrasolar planet) discovered in the orbit of the sun-like star Kepler-11 by NASA's Kepler spacecraft, which searches for planets that transit (cross in front of) their host stars. Kepler-11f is the fifth planet from i ...

Kepler-11g Kepler-11g is an exoplanet discovered in the orbit of the sunlike star Kepler-11 by the Kepler spacecraft, a NASA satellite tasked with searching for terrestrial planets. Kepler-11g is the outermost of the star's six planets. The planet orbits at ...

* Kepler-12b * Kepler-14b * Kepler-15b

References

External links

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