Kepler-5b
Encyclopedia
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 location of a possibly transiting planet, and was reclassified as a Kepler Object of Interest
until follow-up observations confirmed the planet's existence and many of its characteristics. The planet's discovery was announced at a meeting of the American Astronomical Society
on January 4, 2010. The planet has approximately twice the mass of Jupiter
, and is about 1.5 times larger. It is also fifteen times hotter than Jupiter. Kepler-5b orbits Kepler-5 every 3.5 days at a distance of approximately 0.051 AU
(7.6 Gm).
and reclassified as Kepler Objects of Interest
. Kepler-5 was one of these objects of interest, and was given the designation KOI-18.
After the stellar parameters were established, the Kepler science team ran models and fits to ensure that Kepler-5's transit event was not a false positive, such as an eclipsing binary star. Once the planetary nature of Kepler-5b was established, the Kepler team searched for the planet's occultation
behind its star, hoping to find the temperature on its day side. They found both, and were able to set the equilibrium temperature of the planet. The use of speckle imaging
using adaptive optics
at the WIYN Observatory
in Arizona and the Palomar Observatory
in California isolated the starlight of Kepler-5 from background stars.
Use of the Fibre-fed Echelle Spectrograph (FIES) at the Nordic Optical Telescope
on the Canary Islands on June 4, 2009 provided data that was used to determine the star's stellar classification
. The W.M. Keck Observatory's High Resolution Echelle Spectrometer (HIRES), which was used on June 3–6, 2009, and July 2–4, 2009, determined radial velocity measurements for the star, which helped to further define stellar parameters.
Kepler-5 has, as considered by the Kepler team, the potential for use in the study of planets in extreme conditions; its high temperature, large size, and short orbital period
contribute to the aforementioned conditions. The findings of the Kepler team, which also included planets Kepler-4b
, Kepler-6b
, Kepler-7b
, and Kepler-8b
, were announced at the 215th meeting of the American Astronomical Society
of January 4, 2010.
constellation that is expected to soon deplete its hydrogen stores in the core and begin fusing hydrogen in the shell region surrounding the core. The star is 1.374 times the mass
of the Sun (another model suggests that Kepler-5 as a mass of 1.21 times that of the Sun), although it is more diffuse at 1.793 times the Sun's radius. The star's metallicity
is measured to be at [Fe/H] = 0.04, which means that Kepler-5 has 1.10 times the levels of iron
as the Sun does.
The star's apparent magnitude
is 13.4, meaning that it cannot be seen with the unaided eye.
with a mass that is 2.114 times that of Jupiter
and a radius of 1.431 times Jupiter's radius. This also means that Kepler-5b is not very dense. The planet's measured density is 0.894 grams/cm3, less than that of pure water and comparable only to the density of Saturn, which is approximately 0.69 grams/cm3. The planet has an equilibrium temperature of 1868 K, making it fifteen times hotter than Jupiter.
Kepler-5b orbits its host star every 3.5485 days at a mean distance of 0.05064 AU
. In addition, with an orbital inclination of 86.3º, Kepler-5b orbits Kepler-5 almost edge-on with respect to Earth. In comparison, planet Mercury
orbits the Sun at a distance of .387 AU every 87.97 days.
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...
's Kepler spacecraft. It is a Hot Jupiter
Hot Jupiter
Hot Jupiters are a class of extrasolar planet whose mass is close to or exceeds that of 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 location of a possibly transiting planet, and was reclassified as a Kepler Object of Interest
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...
until follow-up observations confirmed the planet's existence and many of its characteristics. The planet's discovery 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. The planet has approximately twice 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 is about 1.5 times larger. It is also fifteen times hotter than Jupiter. Kepler-5b orbits Kepler-5 every 3.5 days at a distance of approximately 0.051 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
(7.6 Gm).
Observational history
The Kepler spacecraft's first days of science activity revealed a series of transit events, in which some body (such as a planet) crosses in front of, and therefore dims, its host star. Such objects were taken from the Kepler Input CatalogKepler Input Catalog
The Kepler Input Catalog is a publicly searchable database of roughly 13.2 million targets used for the Kepler Spectral Classification Program and Kepler....
and reclassified as Kepler Objects of Interest
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...
. Kepler-5 was one of these objects of interest, and was given the designation KOI-18.
After the stellar parameters were established, the Kepler science team ran models and fits to ensure that Kepler-5's transit event was not a false positive, such as an eclipsing binary star. Once the planetary nature of Kepler-5b was established, the Kepler team searched for the planet's 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...
behind its star, hoping to find the temperature on its day side. They found both, and were able to set the equilibrium temperature of the planet. The use of 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...
using adaptive optics
Adaptive optics
Adaptive optics is a technology used to improve the performance of optical systems by reducing the effect of wavefront distortions. It is used in astronomical telescopes and laser communication systems to remove the effects of atmospheric distortion, and in retinal imaging systems to reduce the...
at the WIYN Observatory
WIYN Observatory
The WIYN Observatory is owned and operated by the WIYN Consortium. Its telescope, a 3.5-meter instrument, is the newest and second largest telescope on Kitt Peak in Arizona...
in Arizona and the Palomar Observatory
Palomar Observatory
Palomar Observatory is a privately owned observatory located in San Diego County, California, southeast of Pasadena's Mount Wilson Observatory, in the Palomar Mountain Range. At approximately elevation, it is owned and operated by the California Institute of Technology...
in California isolated the starlight of Kepler-5 from background stars.
Use of the Fibre-fed Echelle Spectrograph (FIES) at the Nordic Optical Telescope
Nordic Optical Telescope
The Nordic Optical Telescope is an astronomical telescope located at Roque de los Muchachos Observatory, La Palma in the Canary Islands. First light came in 1988, with regular observing beginning in 1989. It is funded by Denmark, Sweden, Iceland, Norway and Finland...
on the Canary Islands on June 4, 2009 provided data that was used to determine the star's stellar classification
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...
. The W.M. Keck Observatory's High Resolution Echelle Spectrometer (HIRES), which was used on June 3–6, 2009, and July 2–4, 2009, determined radial velocity measurements for the star, which helped to further define stellar parameters.
Kepler-5 has, as considered by the Kepler team, the potential for use in the study of planets in extreme conditions; its high temperature, large size, and short 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...
contribute to the aforementioned conditions. The findings of the Kepler team, which also included 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-6b
Kepler-6b
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-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...
, were 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...
of January 4, 2010.
Host star
Kepler-5 is a subgiant in the CygnusCygnus (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...
constellation that is expected to soon deplete its hydrogen stores in the core and begin fusing hydrogen in the shell region surrounding the core. The star is 1.374 times the mass
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
of the Sun (another model suggests that Kepler-5 as a mass of 1.21 times that of the Sun), although it is more diffuse at 1.793 times the Sun's radius. The star's 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...
is measured to be at [Fe/H] = 0.04, which means that Kepler-5 has 1.10 times the levels of iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
as the Sun does.
The star's 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...
is 13.4, meaning that it cannot be seen with the unaided eye.
Characteristics
Kepler-5b is a Hot JupiterHot Jupiter
Hot Jupiters are a class of extrasolar planet whose mass is close to or exceeds that of Jupiter...
with a mass that is 2.114 times that of Jupiter
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....
and a radius of 1.431 times Jupiter's radius. This also means that Kepler-5b is not very dense. The planet's measured density is 0.894 grams/cm3, less than that of pure water and comparable only to the density of Saturn, which is approximately 0.69 grams/cm3. The planet has an equilibrium temperature of 1868 K, making it fifteen times hotter than Jupiter.
Kepler-5b orbits its host star every 3.5485 days at a mean distance of 0.05064 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
. In addition, with an orbital inclination of 86.3º, Kepler-5b orbits Kepler-5 almost edge-on with respect to Earth. In comparison, 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...
orbits the Sun at a distance of .387 AU every 87.97 days.