Kepler-6b
Encyclopedia
Kepler-6b is an extrasolar planet
in the orbit of the unusually metal-rich Kepler-6
, a star in the field of view of the NASA
-operated Kepler spacecraft, which searches for planets that cross directly in front of, or transit, their host stars. It was the third planet to be discovered by Kepler. Kepler-6 orbits its host star every three days from a distance of .046 AU
. Its proximity to Kepler-6 inflated the planet, about two-thirds the mass of Jupiter, to slightly larger than Jupiter's size and greatly heated its atmosphere.
Follow-up observations led to the planet's confirmation, which was announced at a meeting of the American Astronomical Society
on January 4, 2010 along with four other Kepler-discovered planets.
's Kepler satellite trails the Earth and continually observes a portion of the sky between the constellations Cygnus
and Lyra. It is devised to search for and discover planets that transit, or cross in front of, their host stars with respect to Earth by measuring small and generally periodic variations in a star's brightness. Kepler recognized a potential transit event around a star that was designated KOI
-017, which was named Kepler-6 after the confirmation of Kepler-6b. The star was designated "6" because it was the sixth planet to be observed (but the third planet to be discovered) by the Kepler satellite.
After the initial detection of a transit signal by Kepler, follow-up observations were taken to confirm the planetary nature of the candidate. Speckle imaging
by the WIYN Telescope was used to determine the amount of light from nearby, background stars that was present. If not accounted for, this light would have made Kepler-6 appear brighter than it actually was. Consequently, the size of Kepler-6b would have been underestimated. Radial velocity
data was taken by HIRES at the Keck I telescope in order to determine the mass of the planet. Independently, observations were made with the Spitzer Space Telescope
at infrared
wavelengths of 3.6 and 4.5 micrometres. Along with additional data taken by Kepler, these observations detected the occultation
of Kepler-6b behind its star.
The confirmation of Kepler-6b was announced at the 215th meeting of the American Astronomical Society
with the discoveries of planets Kepler-4b
, Kepler-5b
, Kepler-7b
, and Kepler-8b
on January 4, 2010.
of 5647 K, Kepler-6 is cooler than the Sun. It is predicted to be 3.8 billion years old, compared to the Sun's age of 4.6 billion years. It is most notable for its unusually high metallicity
for an exoplanet-bearing star; with an [Fe/H] = 0.34, Kepler-6 has 2.18 times more iron than the Sun does. Kepler-6b is the only planet that has been discovered in the orbit of Kepler-6.
, having a mass 0.669 times that of Jupiter, but an average distance of only 0.046 AU
from its star and, thus, an orbital period
of 3.23 days. It is almost 10 times closer to its star than Mercury
is from our Sun. As a result, Kepler-6b is strongly irradiated by its star, heating its atmosphere to a temperature of 1660 K and puffing it up to a size 1.3 times that of Jupiter. It may also be the case that Kepler-6b has a thermal inversion of its atmosphere, where temperature increases with increasing distance from the center of the planet. However, additional observations are required to confirm or refute this possibility.
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...
in the orbit of the unusually metal-rich 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...
, a star in the field of view of the 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...
-operated Kepler spacecraft, which searches for planets that cross directly in front of, or transit, their host stars. It was the third planet to be discovered by Kepler. Kepler-6 orbits its host star every three days from a distance of .046 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
. Its proximity to Kepler-6 inflated the planet, about two-thirds the mass of Jupiter, to slightly larger than Jupiter's size and greatly heated its atmosphere.
Follow-up observations led to the planet's confirmation, which was announced at a meeting of the American Astronomical Society
American Astronomical Society
The American Astronomical Society is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC...
on January 4, 2010 along with four other Kepler-discovered planets.
Discovery and naming
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...
's Kepler satellite trails the Earth and continually observes a portion of the sky between the constellations Cygnus
Cygnus (constellation)
Cygnus is a northern constellation lying on the plane of the Milky Way. Its name is the Latinized Hellenic word for swan. One of the most recognizable constellations of the northern summer and autumn, it features a prominent asterism known as the Northern Cross...
and Lyra. It is devised to search for and discover planets that transit, or cross in front of, their host stars with respect to Earth by measuring small and generally periodic variations in a star's brightness. Kepler recognized a potential transit event around a star that was designated KOI
Kepler Object of Interest
A Kepler Object of Interest is a star observed by the Kepler spacecraft which is suspected of hosting one or more transiting planets. KOIs come from a master list of 150,000 stars which itself is generated from the Kepler Input Catalog . A KOI shows a periodic dimming, indicative of an unseen...
-017, which was named Kepler-6 after the confirmation of Kepler-6b. The star was designated "6" because it was the sixth planet to be observed (but the third planet to be discovered) by the Kepler satellite.
After the initial detection of a transit signal by Kepler, follow-up observations were taken to confirm the planetary nature of the candidate. Speckle imaging
Speckle imaging
Speckle imaging describes a range of high-resolution astronomical imaging techniques based either on the shift-and-add method or on speckle interferometry methods...
by the WIYN Telescope was used to determine the amount of light from nearby, background stars that was present. If not accounted for, this light would have made Kepler-6 appear brighter than it actually was. Consequently, the size of Kepler-6b would have been underestimated. Radial velocity
Radial velocity
Radial velocity is the velocity of an object in the direction of the line of sight . In astronomy, radial velocity most commonly refers to the spectroscopic radial velocity...
data was taken by HIRES at the Keck I telescope in order to determine the mass of the planet. Independently, observations were made with the Spitzer Space Telescope
Spitzer Space Telescope
The Spitzer Space Telescope , formerly the Space Infrared Telescope Facility is an infrared space observatory launched in 2003...
at infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
wavelengths of 3.6 and 4.5 micrometres. Along with additional data taken by Kepler, these observations detected the occultation
Occultation
An occultation is an event that occurs when one object is hidden by another object that passes between it and the observer. The word is used in astronomy . It can also refer to any situation wherein an object in the foreground blocks from view an object in the background...
of Kepler-6b behind its star.
The confirmation of Kepler-6b was announced at the 215th meeting of the American Astronomical Society
American Astronomical Society
The American Astronomical Society is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC...
with the discoveries of 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...
, Kepler-5b
Kepler-5b
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-7b
Kepler-7b
Kepler-7b is one of the first five planets to be confirmed by NASA's Kepler spacecraft, and was confirmed in the first 33.5 days of Kepler's science operations. It is in the orbit of a star that is not as hot as the Sun, but is significantly larger and is expected to soon reach the end of the main...
, and Kepler-8b
Kepler-8b
Kepler-8b is the fifth of the first five exoplanets discovered by NASA's Kepler spacecraft, which aims to discover planets in a region of the sky between the constellations Lyra and Cygnus that transit their host stars. The planet is the hottest of the five...
on January 4, 2010.
Host star
Kepler-6 is a sunlike star in the Cygnus constellation. It is approximately 20.9% more massive than and 39.1% larger than the Sun. With an effective temperatureEffective temperature
The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation...
of 5647 K, Kepler-6 is cooler than the Sun. It is predicted to be 3.8 billion years old, compared to the Sun's age of 4.6 billion years. It is most notable for its unusually high 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...
for an exoplanet-bearing star; with an [Fe/H] = 0.34, Kepler-6 has 2.18 times more iron than the Sun does. Kepler-6b is the only planet that has been discovered in the orbit of Kepler-6.
Characteristics
Kepler-6b is a hot JupiterHot Jupiter
Hot Jupiters are a class of extrasolar planet whose mass is close to or exceeds that of Jupiter...
, having a mass 0.669 times that of Jupiter, but an average distance of only 0.046 AU
Au
-Science:*Absorbance Units, a reporting unit in spectroscopy*Astronomical unit, the average distance between the Earth and the Sun *Atomic units, a system of units convenient for atomic physics and other fields...
from its star and, thus, an orbital period
Orbital period
The orbital period is the time taken for a given object to make one complete orbit about another object.When mentioned without further qualification in astronomy this refers to the sidereal period of an astronomical object, which is calculated with respect to the stars.There are several kinds of...
of 3.23 days. It is almost 10 times closer to its star than 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...
is from our Sun. As a result, Kepler-6b is strongly irradiated by its star, heating its atmosphere to a temperature of 1660 K and puffing it up to a size 1.3 times that of Jupiter. It may also be the case that Kepler-6b has a thermal inversion of its atmosphere, where temperature increases with increasing distance from the center of the planet. However, additional observations are required to confirm or refute this possibility.