Kepler-8b
Encyclopedia
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 (cross in front of) their host stars. The planet is the hottest of the five. Kepler-8b was the first and only planet discovered in Kepler-8
's orbit, and is larger (though more diffuse) than Jupiter
. It orbits its host star every 3.5 days. The planet also demonstrates the Rossiter-McLaughlin effect
, where the planet's orbit affects the redshift
ing of the spectrum of the host star. Kepler-8b was announced to the public on January 4, 2010 at a conference in Washington, D.C. after radial velocity measurements conducted at the W.M. Keck Observatory confirmed its detection by Kepler.
Kepler-8b was the last of the first five planets that Kepler discovered. Its discovery, along with the planets Kepler-4b
, Kepler-5b
, Kepler-6b
, and Kepler-7b
, were announced to the public at the 215th meeting of the American Astronomical Society
in Washington, D.C. This conference took place on January 4, 2010. The discovery of these first five planets helped confirm Kepler's functionality.
s away from Earth. With a mass and radius of, respectively, 1.213 Msun
and 1.486 Rsun, the star is both more massive and wider than the Sun. With an effective temperature
of 6213 K, Kepler-8 is also hotter than the Sun, although it is approximately a three quarters of a billion years younger and is slightly less metal-rich.
, but a radius of 1.419 RJ. This means that although Kepler is approximately 60% the mass of planet Jupiter
, it is more diffuse, as it is 41.9% wider. Based on its size and the distance from its star, Kepler-8b is a Hot Jupiter
planet, orbiting Kepler-8 from a distance of .0483 AU
every 3.52254 days. To compare, planet Mercury
orbits the Sun at an average distance of .3871 AU every 87.97 days. With an equilibrium temperature of 1764 K, Kepler-8b was the hottest of the five planets announced during the conference stating its discovery. Kepler-8b has an eccentricity
of 0, which means that its orbit is very circular. The planet also has a density of .261 grams/cc, approximately 74% less dense than purified water
at 4 °C.
As Kepler-8b orbits its star, it demonstrates the Rossiter-McLaughlin effect
, in which the host star's spectrum becomes red- and, later, blueshifted, as a body transits it. The identification of this effect established Kepler-8b as orbiting in a prograde motion (as opposed to retrograde motion
, in which a planet orbits in a direction opposite of its star's rotation).
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, which aims to discover planets in a region of the sky between the constellations Lyra and 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...
that transit (cross in front of) their host stars. The planet is the hottest of the five. Kepler-8b was the first and only planet discovered in 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...
's orbit, and is larger (though more diffuse) than 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,...
. It orbits its host star every 3.5 days. The planet also demonstrates the Rossiter-McLaughlin effect
Rossiter-McLaughlin effect
The Rossiter–McLaughlin effect is a spectroscopic phenomenon observed when either an eclipsing binary's secondary star or an extrasolar planet is seen to transit across the face of the primary or parent star. As the main star rotates on its axis, one quadrant of its photosphere will be seen to be...
, where the planet's orbit affects the redshift
Redshift
In physics , redshift happens when light seen coming from an object is proportionally increased in wavelength, or shifted to the red end of the spectrum...
ing of the spectrum of the host star. Kepler-8b was announced to the public on January 4, 2010 at a conference in Washington, D.C. after radial velocity measurements conducted at the W.M. Keck Observatory confirmed its detection by Kepler.
Nomenclature and history
Kepler-8b is named because it was the first planet discovered in the orbit of Kepler-8. The star itself (and by extension, its planet) was named after the Kepler spacecraft, a NASA-run satellite that searches for terrestrial planets between constellations Cygnus and Lyra that transit, or cross in front of, their host stars with respect to Earth. This crossing slightly dims the star at a regular interval, which is used to determine if the cause of the fluctuation in brightness is indeed due to a planetary transit. The planet was first noted as a potential transit event by the Kepler telescope, and was originally designated as KOI 10.01. Follow-up observations by the High Resolution Echelle Spectrometer at Hawaii's W.M. Keck Observatory yielded additional information about the planet, including its mass and radius. Kepler-8b was the fifth planet discovered by the Kepler telescope. The first three planets in Kepler's field of view had already been confirmed, and were used to test Kepler's accuracy.Kepler-8b was the last of the first five planets that Kepler discovered. Its discovery, along with the 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-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....
, and 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...
, were announced to the public 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...
in Washington, D.C. This conference took place on January 4, 2010. The discovery of these first five planets helped confirm Kepler's functionality.
Host star
Kepler-8 is an F-type star in the Lyra constellation that lies approximately 1330 (± 180) parsecParsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
s away from Earth. With a mass and radius of, respectively, 1.213 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 1.486 Rsun, the star is both more massive and wider than the Sun. With an effective temperature
Effective 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 6213 K, Kepler-8 is also hotter than the Sun, although it is approximately a three quarters of a billion years younger and is slightly less metal-rich.
Characteristics
Kepler-8b has a mass of .603 MJJupiter 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....
, but a radius of 1.419 RJ. This means that although Kepler is approximately 60% the mass of planet 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,...
, it is more diffuse, as it is 41.9% wider. Based on its size and the distance from its star, Kepler-8b is a Hot Jupiter
Hot Jupiter
Hot Jupiters are a class of extrasolar planet whose mass is close to or exceeds that of Jupiter...
planet, orbiting Kepler-8 from a distance of .0483 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
every 3.52254 days. To compare, 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 an average distance of .3871 AU every 87.97 days. With an equilibrium temperature of 1764 K, Kepler-8b was the hottest of the five planets announced during the conference stating its discovery. Kepler-8b has an 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...
of 0, which means that its orbit is very circular. The planet also has a density of .261 grams/cc, approximately 74% less dense than purified water
Purified water
Purified water is water from any source that is physically processed to remove impurities. Distilled water and deionized water have been the most common forms of purified water, but water can also be purified by other processes including reverse osmosis, carbon filtration, microfiltration,...
at 4 °C.
As Kepler-8b orbits its star, it demonstrates the Rossiter-McLaughlin effect
Rossiter-McLaughlin effect
The Rossiter–McLaughlin effect is a spectroscopic phenomenon observed when either an eclipsing binary's secondary star or an extrasolar planet is seen to transit across the face of the primary or parent star. As the main star rotates on its axis, one quadrant of its photosphere will be seen to be...
, in which the host star's spectrum becomes red- and, later, blueshifted, as a body transits it. The identification of this effect established Kepler-8b as orbiting in a prograde motion (as opposed to retrograde motion
Retrograde motion
Retrograde motion is motion in the direction opposite to the movement of something else, and is the contrary of direct or prograde motion. This motion can be the orbit of one body about another body or about some other point, or the rotation of a single body about its axis, or other phenomena such...
, in which a planet orbits in a direction opposite of its star's rotation).
See also
- Kepler-4bKepler-4bKepler-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-5bKepler-5bKepler-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-6bKepler-6bKepler-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-7bKepler-7bKepler-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...
- Kepler-9bKepler-9bKepler-9b is one of the first planets discovered outside the solar system 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 the Kepler system by transit method; its mass is slightly smaller than the...
- Kepler-10bKepler-10bKepler-10b is the first confirmed terrestrial planet to have been discovered outside the Solar System. Discovered after several months of data collection during the course of the NASA-directed Kepler Mission, which aims to discover Earth-like planets crossing in front of their host stars, the...