Kepler-4 is a sunlike star located about 1626 light-years away 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 ...

Draco. It is in the field of view of the

Kepler Mission 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 ...

, 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 ...

operation purposed with finding Earth-like planets.

Kepler-4b Kepler-4b, initially known as KOI 7.01, is an extrasolar planet first detected as a transit by the Kepler spacecraft. Its radius and mass are similar to that of Neptune; however, due to its proximity to its host star, it is substantially hotter ...

, a Neptune-sized planet that orbits extremely close to its star, was discovered in its orbit and made public by the Kepler team on January 4, 2010. Kepler-4b was the first discovery by the Kepler satellite, and its confirmation helped to demonstrate the spacecraft's effectiveness.

Nomenclature and history

Kepler-4 is named for the

Kepler Johannes Kepler (27 December 1571 – 15 November 1630) was a German astronomer, mathematician, astrologer, natural philosopher and writer on music. He is a key figure in the 17th-century Scientific Revolution, best known for his laws of p ...

spacecraft, a

telescope tasked with finding Earth-like planets that

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 ...

their stars as seen from

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

. As the previous three planets that Kepler confirmed had already been confirmed by others, Kepler-4 and its planet were the first to be discovered by the Kepler team. The star and its system were announced 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 ...

at the 215th meeting of the American Astronomical Society on January 4, 2010, along with Kepler-5, Kepler-6, Kepler-7, and Kepler-8. Of the presented planets,

was the smallest, around the size of planet

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 ...

. The discovery of Kepler-4b and the other planets presented at the AAS meeting helped to confirm that the Kepler spacecraft was indeed functional. The

Harlan J. Smith Telescope The Harlan J. Smith Telescope is a telescope located at the McDonald Observatory, in Texas, in the United States. This telescope is one of several research telescopes that are part of the University of Texas at Austin observatory perched on M ...

McDonald Observatory McDonald Observatory is an astronomical observatory located near unincorporated community of Fort Davis in Jeff Davis County, Texas, United States. The facility is located on Mount Locke in the Davis Mountains of West Texas, with additional faci ...

in Fort Davis,

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

was used by astronomers from the

University of Texas The University of Texas at Austin (UT Austin, UT, or Texas) is a public research university in Austin, Texas, United States. Founded in 1883, it is the flagship institution of the University of Texas System. With 53,082 students as of fall 2 ...

Austin Austin refers to: Common meanings * Austin, Texas, United States, a city * Austin (given name), a list of people and fictional characters * Austin (surname), a list of people and fictional characters * Austin Motor Company, a British car manufac ...

to follow up on Kepler's discoveries and confirm them. Telescopes in

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

, and the

Canary Islands The Canary Islands (; ) or Canaries are an archipelago in the Atlantic Ocean and the southernmost Autonomous communities of Spain, Autonomous Community of Spain. They are located in the northwest of Africa, with the closest point to the cont ...

were also used to confirm the findings.

Characteristics

Kepler-4 is a G0-type star, which is similar to the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

, except slightly brighter. The star is 1.117 M_sun and 1.555 R_sun, or 111% the mass of and 155% the radius of the Sun. With a

metallicity In astronomy, metallicity is the Abundance of the chemical elements, abundance of Chemical element, elements present in an object that are heavier than hydrogen and helium. Most of the normal currently detectable (i.e. non-Dark matter, dark) matt ...

of .09 (± 0.10) e/H Kepler-4 is more metal-rich than the Sun, a figure that is important in that metal-rich stars tend to have orbiting planets more often than metal-poor stars. Kepler-4 is also about 6.7 billion years old. In comparison, the Sun is 4.6 billion years old. In addition, Kepler-4 has an effective temperature of 5781 (± 76) K, which is almost identical, within the errors, to that of the Sun, which is 5778 K. As seen from

, Kepler-4 has an

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

of 12.7. It is, as a result, not visible with the naked eye.

Planetary system

's discovery was announced on January 4, 2010. It is the size of planet

, at 0.077 M_J (7% the mass of

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...

) and 0.357 R_J (36% the radius of Jupiter). The planet orbits its star every 3.213 days at 0.045 AU from the star. This distance compares to planet Mercury, which is 0.39 AU from the Sun. Kepler-4'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 a subsequent independent reanalysis of the discovery data found a value of 0.25 ± 0.12. Likewise, the temperature of the planet is assumed to be 1650 K, far hotter than Jupiter's, which is assumed to be 124 K (not considering its internal heat and atmosphere). A search for

transit-timing variation Transit-timing variation is a method for detecting exoplanets by observing variations in the timing of a transit. This provides an extremely sensitive method capable of detecting additional planets in the system with masses potentially as small a ...

s in all 17 quarters of Kepler data did not detect any evidence of additional planets. Kepler-4 System

References

{{DEFAULTSORT:Kepler-4 G-type main-sequence stars Planetary systems with one confirmed planet Draco (constellation) 7 Planetary transit variables

Nomenclature and history

Characteristics

Planetary system

See also

References