Kepler-10b
Encyclopedia
Kepler-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 planet's discovery was announced on January 10, 2011. Kepler-10b has a mass between 3.3 and 5.7 Earth mass
es and a radius of 1.4 Earth radii
. However, it lies extremely close to its star, Kepler-10
, and as a result is too hot to support life. Its existence was confirmed using measurements from the W.M. Keck Observatory in Hawaii.
, the star that hosts Kepler-10b, is located 560 light-year
s from our solar system in the Draco constellation
. It is approximately the same size as the Sun
, with an estimated age of 12 billion years. Planet Kepler-10b was the first planet to be discovered in the orbit of its star. For this, it was designated the star's b planet. The star, in turn, was named for the Kepler Mission, a NASA-led operation aimed at discovering terrestrial planets that transit, or cross in front of, their host stars with respect to Earth. The planet's discovery was announced to the public on January 10, 2011.
The transit method of discovering exoplanet
s relies upon carefully monitoring the brightness of a star. If a planet is present and crosses the line of sight between Earth and the star, the star will dim at a regular interval by an amount that depends upon the radius of the transiting planet. In order to measure the mass of a planet, and rule out other phenomena that can mimic the presence of a planet transiting a star, candidate transiting planets are followed up with the radial velocity method of detecting extrasolar planets.
Kepler-10b's discovery was based on eight months of data collected with the Kepler telescope from May 2009 to January 2010. The planet's first transits were observed in July 2009. According to the collected data, Kepler-10 dimmed by one part in ten thousand every 0.83 days. Kepler-10 was the first star in the field of view
of the Kepler telescope identified as capable of harboring a small transiting planet, and was considered a high priority target for ground based radial velocity observations intended to confirm the mass of Kepler-10b. Radial velocity measurements with the Keck I telescope taken intermittently between August 2009 and August 2010 revealed a periodic Doppler shift in the spectrum of Kepler-10 consistent with a planet of the nature observed by Kepler, confirming the planet's existence and allowing its mass to be determined. The planet's discovery was announced to the public on January 10, 2011.
On January 13, 2011, 3 days after the planet's discovery was announced, The Economist
published an article suggesting “Vulcan” as an unofficial name for the planet, after both the hypothetical planet
, and the Roman god of the same name
.
at Berkeley
said that the discovery was ranked “as among the most profound scientific discoveries in human history,” and that the planet “will go into every textbook worldwide.” Marcy also described Kepler-10b as "a bridge between the gas giant planets we’ve been finding and the Earth itself." Diana Valencia at the University of Côte d'Azur in Nice, France considered the planet more of a "super-Mercury" than a super-Earth, granted its physical characteristics.
, and a mass estimated at 4.6 times that of Earth. The large range of uncertainty in mass (and subsequently density) is due to the difficulty in obtaining sufficiently precise radial velocity measurements for such a, relatively speaking, small object. The density of Kepler-10b is 8.8 g
cm−3, substantially higher than that of Earth, and is comparable to that of iron
. In the least-dense case for the density estimate, Kepler-10b would still be as dense as the Earth. It orbits its star, Kepler-10
, in less than a day, at less than a twentieth of the distance from Mercury
to the Sun
. Its surface temperature on the star lit side is approximately 1833 K
, which is as hot as a blast furnace
and hot enough to melt iron.
Though CoRoT-7b was discovered before Kepler-10b and has been claimed to be rocky, there is more room for other interpretations in the case of CoRoT-7b's composition than there is for Kepler-10b. This is due to the much larger uncertainty in CoRoT-7b's mass (and, to a lesser extent, its radius) which is illustrated in the plot to the left. Consequently, CoRoT-7b may be revealed to be an ocean planet
, whereas Kepler-10b must be predominantly made of rock or iron. In addition to showing the range of masses and radii consistent with the observations of each planet, the plot includes curves of compositions implied by certain masses and radii.
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...
to have been discovered outside the Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
. Discovered after several months of data collection during the course 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...
-directed 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...
, which aims to discover 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...
-like planets crossing in front of their host stars, the planet's discovery was announced on January 10, 2011. Kepler-10b has a mass between 3.3 and 5.7 Earth mass
Earth mass
Earth mass is the unit of mass equal to that of the Earth. 1 M⊕ = 5.9722 × 1024 kg. Earth mass is often used to describe masses of rocky terrestrial planets....
es and a radius of 1.4 Earth radii
Earth radius
Because the Earth is not perfectly spherical, no single value serves as its natural radius. Distances from points on the surface to the center range from 6,353 km to 6,384 km...
. However, it lies extremely close to its star, Kepler-10
Kepler-10
Kepler-10, formerly known as KOI-72, is a sunlike star in constellation Draco that lies 173 parsecs away from the Earth. Kepler-10 was targeted by NASA's Kepler spacecraft, as it was seen the first star identified by the Kepler mission as a possible host to a small, transiting exoplanet...
, and as a result is too hot to support life. Its existence was confirmed using measurements from the W.M. Keck Observatory in Hawaii.
Nomenclature and history
Kepler-10Kepler-10
Kepler-10, formerly known as KOI-72, is a sunlike star in constellation Draco that lies 173 parsecs away from the Earth. Kepler-10 was targeted by NASA's Kepler spacecraft, as it was seen the first star identified by the Kepler mission as a possible host to a small, transiting exoplanet...
, the star that hosts Kepler-10b, is located 560 light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s from our solar system in the Draco constellation
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 approximately the same size as the Sun
Sun
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...
, with an estimated age of 12 billion years. Planet Kepler-10b was the first planet to be discovered in the orbit of its star. For this, it was designated the star's b planet. The star, in turn, was named for the Kepler Mission, a NASA-led operation aimed at discovering terrestrial planets that transit, or cross in front of, their host stars with respect to Earth. The planet's discovery was announced to the public on January 10, 2011.
The transit method of discovering exoplanet
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...
s relies upon carefully monitoring the brightness of a star. If a planet is present and crosses the line of sight between Earth and the star, the star will dim at a regular interval by an amount that depends upon the radius of the transiting planet. In order to measure the mass of a planet, and rule out other phenomena that can mimic the presence of a planet transiting a star, candidate transiting planets are followed up with the radial velocity method of detecting extrasolar planets.
Kepler-10b's discovery was based on eight months of data collected with the Kepler telescope from May 2009 to January 2010. The planet's first transits were observed in July 2009. According to the collected data, Kepler-10 dimmed by one part in ten thousand every 0.83 days. Kepler-10 was the first star in the field of view
Field of view
The field of view is the extent of the observable world that is seen at any given moment....
of the Kepler telescope identified as capable of harboring a small transiting planet, and was considered a high priority target for ground based radial velocity observations intended to confirm the mass of Kepler-10b. Radial velocity measurements with the Keck I telescope taken intermittently between August 2009 and August 2010 revealed a periodic Doppler shift in the spectrum of Kepler-10 consistent with a planet of the nature observed by Kepler, confirming the planet's existence and allowing its mass to be determined. The planet's discovery was announced to the public on January 10, 2011.
On January 13, 2011, 3 days after the planet's discovery was announced, The Economist
The Economist
The Economist is an English-language weekly news and international affairs publication owned by The Economist Newspaper Ltd. and edited in offices in the City of Westminster, London, England. Continuous publication began under founder James Wilson in September 1843...
published an article suggesting “Vulcan” as an unofficial name for the planet, after both the hypothetical planet
Vulcan (hypothetical planet)
Vulcan was a small planet proposed to exist in an orbit between Mercury and the Sun. In an attempt to explain peculiarities of Mercury's orbit, in the 19th-century French mathematician Urbain Jean Joseph Le Verrier hypothesized that they were the result of another planet, which he named Vulcan...
, and the Roman god of the same name
Vulcan (mythology)
Vulcan , aka Mulciber, is the god of beneficial and hindering fire, including the fire of volcanoes in ancient Roman religion and Roman Neopaganism. Vulcan is usually depicted with a thunderbolt. He is known as Sethlans in Etruscan mythology...
.
Reaction
Kepler-10b's discovery excited astronomers, who hoped to use data about Kepler-10b to inquire into the formation and structure that terrestrial, Earth-size planets tend to have in common. Geoff Marcy of the University of CaliforniaUniversity of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
at Berkeley
Berkeley, California
Berkeley is a city on the east shore of the San Francisco Bay in Northern California, United States. Its neighbors to the south are the cities of Oakland and Emeryville. To the north is the city of Albany and the unincorporated community of Kensington...
said that the discovery was ranked “as among the most profound scientific discoveries in human history,” and that the planet “will go into every textbook worldwide.” Marcy also described Kepler-10b as "a bridge between the gas giant planets we’ve been finding and the Earth itself." Diana Valencia at the University of Côte d'Azur in Nice, France considered the planet more of a "super-Mercury" than a super-Earth, granted its physical characteristics.
Characteristics
Kepler-10b is most noted for its rocky surface. It has a diameter 1.4 times that of the EarthEarth
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...
, and a mass estimated at 4.6 times that of Earth. The large range of uncertainty in mass (and subsequently density) is due to the difficulty in obtaining sufficiently precise radial velocity measurements for such a, relatively speaking, small object. The density of Kepler-10b is 8.8 g
Gram
The gram is a metric system unit of mass....
cm−3, substantially higher than that of Earth, and is comparable to that 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...
. In the least-dense case for the density estimate, Kepler-10b would still be as dense as the Earth. It orbits its star, Kepler-10
Kepler-10
Kepler-10, formerly known as KOI-72, is a sunlike star in constellation Draco that lies 173 parsecs away from the Earth. Kepler-10 was targeted by NASA's Kepler spacecraft, as it was seen the first star identified by the Kepler mission as a possible host to a small, transiting exoplanet...
, in less than a day, at less than a twentieth of the distance from 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...
to the Sun
Sun
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...
. Its surface temperature on the star lit side is approximately 1833 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...
, which is as hot as a blast furnace
Blast furnace
A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally iron.In a blast furnace, fuel and ore and flux are continuously supplied through the top of the furnace, while air is blown into the bottom of the chamber, so that the chemical reactions...
and hot enough to melt iron.
Though CoRoT-7b was discovered before Kepler-10b and has been claimed to be rocky, there is more room for other interpretations in the case of CoRoT-7b's composition than there is for Kepler-10b. This is due to the much larger uncertainty in CoRoT-7b's mass (and, to a lesser extent, its radius) which is illustrated in the plot to the left. Consequently, CoRoT-7b may be revealed to be an ocean planet
Ocean planet
An ocean planet is a hypothetical type of planet whose surface is completely covered with an ocean of water.Planetary objects that form in the outer solar system begin as a comet-like mixture of roughly half water and half rock by mass...
, whereas Kepler-10b must be predominantly made of rock or iron. In addition to showing the range of masses and radii consistent with the observations of each planet, the plot includes curves of compositions implied by certain masses and radii.
See also
- Kepler MissionKepler MissionThe 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...
- 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...
, 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...
, 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....
, 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...
, 8bKepler-8bKepler-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...
, 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... - List of extrasolar planet extremes