KOI-428
Encyclopedia
KOI-428 is an F-type star with one known planet, KOI-428b
, in orbit. The star is approximately 1.5 times more massive than the Sun, and is over two times its size; it was, at upon its discovery, the largest and the most evolved star yet discovered with a transiting planet in its orbit. KOI-428 was first noted as home to a possible transiting object by the Kepler spacecraft; the data on the system was released to the public. A team of French and Swiss scientists used follow-up data to determine the existence of the Hot Jupiter
planet KOI-428b
, and later had their results published in a scientific journal on January 4, 2011.
operation that searches for planets that transit, or cross in front of, their host stars. It was labeled a Kepler Object of Interest
(KOI) during the satellite's first 33.5 days of operations, which stretched from mid-May to mid-June 2009, because of the detection of a potential transit event. The data collected by Kepler's photometer
was publicly released, including data on KOI-428 and its possible transiting companion.
Data on KOI-428 was analyzed by a team of French and Swiss astronomers, who first tested for false positives. When all obvious false positives were cleared, the science team used the SOPHIE échelle spectrograph
at the Haute-Provence Observatory
in southern France to gather radial velocity measurements on the star. Collected data was then checked to see if it corresponded with that of a closely orbiting binary star
or that of a planet; it was found to be that of a planet, leading to the confirmation of KOI-428b
.
After KOI-428b was confirmed, the French and Swiss science team worked to clarify the stellar parameters of KOI-428 by analyzing the star's spectrum as collected by SOPHIE. KOI-428 is the sixth known planetary host star with a radius of more than 1.8 times that of the Sun. At the time of its discovery, KOI-428 was the most evolved star known to have a transiting planet.
KOI-428 and its exoplanet were published in the journal Astronomy and Astrophysics
on January 4, 2011, after being submitted on September 15, 2010.
of the Sun and 2.13 times its radius. The star has an effective temperature
of 6510 K, making it hotter than the Sun. Its metallicity
of [Fe/H] = 0.10 means that KOI-428 has 1.26 times as much iron as the Sun does.
KOI-428 was, at the time of its discovery, the largest and most evolved star known to host a transiting planet. It is the sixth known host star with a radius over 1.8 times that of the Sun and a transiting planet, after stars that include Kepler-5
and Kepler-7
.
KOI-428 lies 2700 parsec
s (8,806.4 light years) away from Earth, further than any star (with a known distance) with an exoplanet previously discovered by Kepler. With an apparent magnitude
of 14.58, it was also dimmer than any star previously recognized by Kepler. Because of its low apparent magnitude, KOI-428 cannot be seen with the naked eye
.
is the first (and only) planet discovered in the orbit of KOI-428. It has a mass
that is 2.2 times that of Jupiter's, the rough equivalent of 700 Earths. The planet also has a radius that is 1.17 times that of Jupiter and a density of 1.68 grams/cm3. KOI-428b has an equilibrium temperature of 1620 K, over six times hotter than the equilibrium temperature of Earth. It orbits its star every 6.87 days at a distance of 0.081 AU
.
KOI-428b
KOI-428b is a Hot Jupiter-type planet discovered in the orbit of the star KOI-428, which is about to become a red giant. The planet was first noted as a transit event by NASA's Kepler spacecraft...
, in orbit. The star is approximately 1.5 times more massive than the Sun, and is over two times its size; it was, at upon its discovery, the largest and the most evolved star yet discovered with a transiting planet in its orbit. KOI-428 was first noted as home to a possible transiting object by the Kepler spacecraft; the data on the system was released to the public. A team of French and Swiss scientists used follow-up data to determine the existence of the Hot Jupiter
Hot Jupiter
Hot Jupiters are a class of extrasolar planet whose mass is close to or exceeds that of Jupiter...
planet KOI-428b
KOI-428b
KOI-428b is a Hot Jupiter-type planet discovered in the orbit of the star KOI-428, which is about to become a red giant. The planet was first noted as a transit event by NASA's Kepler spacecraft...
, and later had their results published in a scientific journal on January 4, 2011.
Observational history
KOI-428 was first targeted by the Kepler spacecraft, an Earth-trailing 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...
operation that searches for planets that transit, or cross in front of, their host stars. It was labeled 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...
(KOI) during the satellite's first 33.5 days of operations, which stretched from mid-May to mid-June 2009, because of the detection of a potential transit event. The data collected by Kepler's photometer
Photometer
In its widest sense, a photometer is an instrument for measuring light intensity or optical properties of solutions or surfaces. Photometers are used to measure:*Illuminance*Irradiance*Light absorption*Scattering of light*Reflection of light*Fluorescence...
was publicly released, including data on KOI-428 and its possible transiting companion.
Data on KOI-428 was analyzed by a team of French and Swiss astronomers, who first tested for false positives. When all obvious false positives were cleared, the science team used the SOPHIE échelle spectrograph
SOPHIE échelle spectrograph
The SOPHIE échelle spectrograph is a high-resolution echelle spectrograph installed on the 1.93m reflector telescope at the Haute-Provence Observatory located in south-eastern France...
at the Haute-Provence Observatory
Haute-Provence Observatory
The Observatoire de Haute-Provence was established in 1937 as a national facility for French astronomers. Astronomical observations began in 1943 using the 1.20 m telescope, and the first research papers based on observations made at the observatory were published in 1944...
in southern France to gather radial velocity measurements on the star. Collected data was then checked to see if it corresponded with that of a closely orbiting binary star
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
or that of a planet; it was found to be that of a planet, leading to the confirmation of KOI-428b
KOI-428b
KOI-428b is a Hot Jupiter-type planet discovered in the orbit of the star KOI-428, which is about to become a red giant. The planet was first noted as a transit event by NASA's Kepler spacecraft...
.
After KOI-428b was confirmed, the French and Swiss science team worked to clarify the stellar parameters of KOI-428 by analyzing the star's spectrum as collected by SOPHIE. KOI-428 is the sixth known planetary host star with a radius of more than 1.8 times that of the Sun. At the time of its discovery, KOI-428 was the most evolved star known to have a transiting planet.
KOI-428 and its exoplanet were published in the journal Astronomy and Astrophysics
Astronomy and Astrophysics
* Astronomy and Astrophysics has a 2010 impact factor of 4.410.-See also:*The Astronomy and Astrophysics Review*Advanced Satellite for Cosmology and Astrophysics*Astronomy & Geophysics*Astronomical Journal*Astrophysical Journal...
on January 4, 2011, after being submitted on September 15, 2010.
Characteristics
KOI-428 is an F-type star that is 1.48 times the massSolar 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 and 2.13 times its radius. The star has 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 6510 K, making it hotter than the Sun. Its 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 [Fe/H] = 0.10 means that KOI-428 has 1.26 times as much iron as the Sun does.
KOI-428 was, at the time of its discovery, the largest and most evolved star known to host a transiting planet. It is the sixth known host star with a radius over 1.8 times that of the Sun and a transiting planet, after stars that include 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...
and 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...
.
KOI-428 lies 2700 parsec
Parsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
s (8,806.4 light years) away from Earth, further than any star (with a known distance) with an exoplanet previously discovered by Kepler. With 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 14.58, it was also dimmer than any star previously recognized by Kepler. Because of its low apparent magnitude, KOI-428 cannot be seen with the naked eye
Naked eye
The naked eye is a figure of speech referring to human visual perception unaided by a magnifying or light-collecting optical device, such as a telescope or microscope. Vision corrected to normal acuity using corrective lenses is considered "naked"...
.
Planetary system
KOI-428bKOI-428b
KOI-428b is a Hot Jupiter-type planet discovered in the orbit of the star KOI-428, which is about to become a red giant. The planet was first noted as a transit event by NASA's Kepler spacecraft...
is the first (and only) planet discovered in the orbit of KOI-428. It has a mass
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....
that is 2.2 times that of Jupiter's, the rough equivalent of 700 Earths. The planet also has a radius that is 1.17 times that of Jupiter and a density of 1.68 grams/cm3. KOI-428b has an equilibrium temperature of 1620 K, over six times hotter than the equilibrium temperature of Earth. It orbits its star every 6.87 days at a distance of 0.081 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
.