Kepler-4
Encyclopedia
Kepler-4 is a sunlike star located about 1631 light-years away in the constellation
Draco
. It is in the field of view of the Kepler Mission
, a NASA
operation purposed with finding Earth-like planets
. Kepler-4b
, 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.
telescope tasked with finding Earth-like planets
that transit their stars as seen from Earth
. As the previous three planets that Kepler confirmed had already been confirmed by other finds, 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.
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, Kepler-4b
was the smallest, around the size of planet Neptune
. 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
at McDonald Observatory
in Fort Davis
, Texas
was used by astronomers from the University of Texas
at Austin
to follow up on Kepler's discoveries and confirm them. Telescopes in Hawaii
, California
, Arizona
, and the Canary Islands
were also used to confirm the findings.
, except slightly brighter. The star is 1.223 Msun
and 1.487 Rsun, or 122% the mass of and 148% the radius of the Sun. With a metallicity
of .17 (± 0.06) [Fe/H], Kepler-4 is more metal-rich than the Sun by 48%, 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 4.5 (± 1.5) billion years old. In comparison, the Sun is 4.6 billion years old. In addition, Kepler-4 has an effective temperature of 5857 (± 120) K, compared to that of the Sun, which is 5778 K.
As seen from Earth
, Kepler-4 has an apparent magnitude
of 12.7. It is, as a result, not visible with the naked eye.
's discovery was announced on January 4, 2010. It is the size of planet Neptune
, at .077 MJ
(7% the mass of Jupiter
) and .357 RJ (36% the radius of Jupiter). The planet orbits its star every 3.214 days at .045 AU
from the star. This distance compares to planet Mercury
, which is .39 AU from the Sun. Kepler-4's eccentricity
is assumed to be 0, which by definition would give it a circular orbit. 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).
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Draco
Draco (constellation)
Draco is a constellation in the far northern sky. Its name is Latin for dragon. Draco is circumpolar for many observers in the northern hemisphere...
. It is in the field of view of the Kepler Mission
Kepler Mission
The Kepler spacecraft is an American space observatory, the space-based portion of NASA's Kepler Mission to discover Earth-like planets orbiting other stars. The spacecraft is named in honor of the 17th-century German astronomer Johannes Kepler...
, a NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
operation purposed with finding Earth-like planets
Terrestrial planet
A terrestrial planet, telluric planet or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun...
. Kepler-4b
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 than any planet in the Solar System. The planet's...
, 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 spacecraft, a NASANASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
telescope tasked with finding Earth-like planets
Terrestrial planet
A terrestrial planet, telluric planet or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun...
that transit their stars as seen from Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
. As the previous three planets that Kepler confirmed had already been confirmed by other finds, 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.
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....
at the 215th meeting of the American Astronomical Society on January 4, 2010, along with Kepler-5
Kepler-5
Kepler-5 is a star located in the constellation Cygnus in the field of view of the Kepler Mission, a NASA project aimed at detecting planets in transit of, or passing in front of, their host stars as seen from Earth. One closely orbiting, Jupiter-like planet, named Kepler-5b, has been detected...
, Kepler-6
Kepler-6
Kepler-6 is a yellow giant situated in the constellation Cygnus. The star lies within the field of view of the Kepler Mission, which discovered it as part of a NASA-led mission to discover Earth-like planets...
, Kepler-7
Kepler-7
Kepler-7 is a star located in the constellation Lyra in the field of view of the Kepler Mission, a NASA operation in search of Earth-like planets. It is home to the fourth of the first five planets that Kepler discovered; this planet, a Jupiter-size gas giant named Kepler-7b, is as light as styrofoam...
, and Kepler-8
Kepler-8
| class=F5VKepler-8 is a star located in the constellation Lyra in the field of view of the Kepler Mission, a NASA-led operation tasked with discovering terrestrial planets. The star, which is slightly hotter, larger, and more massive than the Sun, has one gas giant in its orbit, Kepler-8b. This...
. Of the presented planets, Kepler-4b
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 than any planet in the Solar System. The planet's...
was the smallest, around the size of planet Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...
. 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
Harlan J. Smith Telescope
The Harlan J. Smith Telescope is a 2.7m 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 atop Mount Locke in the Davis Mountains of west Texas...
at McDonald Observatory
McDonald Observatory
The McDonald Observatory is an astronomical observatory located near the unincorporated community of Fort Davis in Jeff Davis County, Texas, United States. The facility is located on Mount Fowlkes and Mount Locke in the Davis Mountains of West Texas...
in Fort Davis
Fort Davis, Texas
Fort Davis is a census-designated place in Jeff Davis County, Texas, United States. The population was 1,050 at the 2000 census and 1,041 according to a 2007 estimate. It is the county seat of Jeff Davis County...
, Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
was used by astronomers from the University of Texas
University of Texas at Austin
The University of Texas at Austin is a state research university located in Austin, Texas, USA, and is the flagship institution of the The University of Texas System. Founded in 1883, its campus is located approximately from the Texas State Capitol in Austin...
at Austin
Austin
Austin is the capital of the U.S. state of Texas.Austin may also refer to:-In the United States:*Austin, Arkansas*Austin, Colorado*Austin, Chicago, Illinois*Austin, Indiana*Austin, Minnesota*Austin, Nevada*Austin, Oregon...
to follow up on Kepler's discoveries and confirm them. Telescopes in Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
, and the Canary Islands
Canary Islands
The Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...
were also used to confirm the findings.
Characteristics
Kepler-4 is a G0-type star, which is similar to the SunSun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
, except slightly brighter. The star is 1.223 Msun
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
and 1.487 Rsun, or 122% the mass of and 148% the radius of the Sun. With a metallicity
Metallicity
In astronomy and physical cosmology, the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium...
of .17 (± 0.06) [Fe/H], Kepler-4 is more metal-rich than the Sun by 48%, 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 4.5 (± 1.5) billion years old. In comparison, the Sun is 4.6 billion years old. In addition, Kepler-4 has an effective temperature of 5857 (± 120) K, compared to that of the Sun, which is 5778 K.
As seen from Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
, Kepler-4 has an apparent magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
of 12.7. It is, as a result, not visible with the naked eye.
Planetary system
Kepler-4bKepler-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 than any planet in the Solar System. The planet's...
's discovery was announced on January 4, 2010. It is the size of planet Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...
, at .077 MJ
Jupiter mass
Jupiter mass , is the unit of mass equal to the total mass of the planet Jupiter . Jupiter mass is used to describe masses of the gas giants, such as the outer planets and extrasolar planets. It is also used in describing brown dwarfs....
(7% the mass of Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
) and .357 RJ (36% the radius of Jupiter). The planet orbits its star every 3.214 days at .045 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
from the star. This distance compares to planet Mercury
Mercury (planet)
Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 Earth days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about its axis for every two orbits...
, which is .39 AU from the Sun. Kepler-4's eccentricity
Orbital eccentricity
The orbital eccentricity of an astronomical body is the amount by which its orbit deviates from a perfect circle, where 0 is perfectly circular, and 1.0 is a parabola, and no longer a closed orbit...
is assumed to be 0, which by definition would give it a circular orbit. 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).