GJ 3634
Encyclopedia
GJ 3634 is a red dwarf
star in the Hydra
constellation. One planet has been discovered in its orbit, GJ 3634 b
. GJ 3634 is under half the mass and size of the Sun, and is estimated to be at least a billion years younger, and lies near to Earth, with a distance of 19.8 parsec
s (64.6 light years). It was targeted by astronomers during an over six-year survey of red dwarfs. The astronomers had recently changed their strategy to search for planets with extremely short orbits so they could narrow down candidates that transited, or crossed in front of, their host stars as seen from the Earth. The Super-Earth
GJ 3634 b was the first planet discovered using this new strategy. The planet was confirmed using Doppler spectroscopy
, or the observation and extrapolation of data from a recorded Doppler effect
in the star's light, but later observations found no transiting pattern. The planet was published by its discoverers on February 8, 2011.
; a later expansion of the original catalogue was compiled jointly by Gliese and Hartmut Jahreiß
. The Third Catalogue, the most recent catalogue, was formed to tag all then-known stars within 25 parsecs of Earth (81.54 light years). GJ 3634 was first catalogued in 1987. The discoverers of GJ 3634 b worked through the High Accuracy Radial Velocity Planet Searcher
(HARPS) at the European Southern Observatory
's La Silla Observatory
in Chile for over six years in search of planets that orbited low-mass red dwarfs. After the discoveries of eleven prior planets, the researchers changed their strategy to search for planets with extremely short orbits. They would first discover the system using the radial velocity method, in which an observed Doppler shift in the star's light would be measured and interpreted; and would then follow up with a search for transits, in which the planet crosses in front of and dims its star as seen from Earth. Radial velocity measurements would help determine the most efficient and time-effective means of observing potential planetary transits.
Radial velocity measurements revealed the existence of a planet with a mass of at least 7 Earths. This planet, GJ 3634 b
, became the first planet to be discovered under the new strategy. The team of astronomers then followed up with transit measurements using instruments on the Spitzer Space Telescope
; they found that there was most likely no transit event present at the star, but they were able to discover its true mass. GJ 3634 b was published to the journal Astronomy and Astrophysics
on February 8, 2011.
, a cool, small and dim star that shines with reddish light. It lies in the Hydra
constellation. The star is 45% the mass
of the Sun, and is 43% the Sun's size. GJ 3634, described by its discoverers as an "intermediately active star," has a luminosity
of 0.02, meaning that it releases about 2% of the energy that the Sun radiates. The star is relatively metal-poor; with a metallicity
of [Fe/H] -0.10, GJ 3634 has 79% the amount of iron that has been measured in the Sun. The star is younger than the Sun, with an estimated age of at most three billion years.
GJ 3634 has an apparent magnitude
of 11.95. Thus, despite its proximity at 19.8 parsec
s (64.6 light years) away from the Earth, it cannot be seen with the unaided eye. The star is of a similar distance from Earth as planet-bearing 51 Pegasi
, which lies at a distance of 14.7 parsecs (47.95 light years).
. The planet was called a Super-Earth
by its discoverers because of its mass, which was deduced to be 8.4 times that of Earth's and 0.02 times that of Jupiter's. GJ 3634 b has an extremely short orbital period
, orbiting GJ 3634 every 2.64561 days. The planet orbits near to its star, and is at an average distance of .0287 AU
away. It has an orbital eccentricity
of 0.08, meaning that its orbit is very circular.
The initial study into the system suggests that a second planet in the inner system is unlikely. The discoverers of GJ 3634 b, however, noted the signal of a secondary body of an unknown nature that most likely orbits GJ 3634 every 200 days with a mass that is at most double that of Neptune
.
Red dwarf
According to the Hertzsprung-Russell diagram, a red dwarf star is a small and relatively cool star, of the main sequence, either late K or M spectral type....
star in the Hydra
Hydra (constellation)
Hydra is the largest of the 88 modern constellations, measuring 1303 square degrees. It has a long history, having been included among the 48 constellations listed by the 2nd century astronomer Ptolemy. It is commonly represented as a water snake...
constellation. One planet has been discovered in its orbit, GJ 3634 b
GJ 3634 b
GJ 3634 b is a Super-Earth in the orbit of the nearby red dwarf GJ 3634. The planet is approximately eight times the mass of Earth, and orbits its star every two and a half days at a distance of .0287 AU...
. GJ 3634 is under half the mass and size of the Sun, and is estimated to be at least a billion years younger, and lies near to Earth, with a distance of 19.8 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 (64.6 light years). It was targeted by astronomers during an over six-year survey of red dwarfs. The astronomers had recently changed their strategy to search for planets with extremely short orbits so they could narrow down candidates that transited, or crossed in front of, their host stars as seen from the Earth. The Super-Earth
Super-Earth
A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below the mass of the Solar System's gas giants. The term super-Earth refers only to the mass of the planet, and does not imply anything about the surface conditions or habitability...
GJ 3634 b was the first planet discovered using this new strategy. The planet was confirmed using Doppler spectroscopy
Doppler spectroscopy
Doppler spectroscopy, also known as radial velocity measurement, is a spectroscopic method for finding extrasolar planets. It involves the observation of Doppler shifts in the spectrum of the star around which the planet orbits....
, or the observation and extrapolation of data from a recorded Doppler effect
Doppler effect
The Doppler effect , named after Austrian physicist Christian Doppler who proposed it in 1842 in Prague, is the change in frequency of a wave for an observer moving relative to the source of the wave. It is commonly heard when a vehicle sounding a siren or horn approaches, passes, and recedes from...
in the star's light, but later observations found no transiting pattern. The planet was published by its discoverers on February 8, 2011.
Naming and discovery
GJ 3634 is named for its location in the Gliese Catalogue of Nearby StarsGliese Catalogue of Nearby Stars
The Gliese Catalogue of Nearby Stars is a frequently referenced, modern star catalogue of stars located within 25 parsecs of the Earth.-First edition and supplements:...
; a later expansion of the original catalogue was compiled jointly by Gliese and Hartmut Jahreiß
Hartmut Jahreiß
Hartmut Jahreiß is a German astronomer associated with Astronomisches Rechen-Institut specializing in the study of nearby stars.-Work:Hartmut Jahreiß obtained his Ph.D from the University of Heidelberg. His thesis was on the spatial distribution, kinetics and age of stars near the Sun...
. The Third Catalogue, the most recent catalogue, was formed to tag all then-known stars within 25 parsecs of Earth (81.54 light years). GJ 3634 was first catalogued in 1987. The discoverers of GJ 3634 b worked through the High Accuracy Radial Velocity Planet Searcher
High Accuracy Radial Velocity Planet Searcher
The High Accuracy Radial velocity Planet Searcher is a high-precision echelle spectrograph installed in 2002 on ESO's 3.6m telescope at La Silla Observatory in Chile. The first light was achieved in February 2003...
(HARPS) at the European Southern Observatory
European Southern Observatory
The European Southern Observatory is an intergovernmental research organisation for astronomy, supported by fifteen countries...
's La Silla Observatory
La Silla Observatory
La Silla Observatory is an astronomical observatory in Chile with three telescopes built and operated by the European Southern Observatory organisation, and several others are partly maintained by ESO...
in Chile for over six years in search of planets that orbited low-mass red dwarfs. After the discoveries of eleven prior planets, the researchers changed their strategy to search for planets with extremely short orbits. They would first discover the system using the radial velocity method, in which an observed Doppler shift in the star's light would be measured and interpreted; and would then follow up with a search for transits, in which the planet crosses in front of and dims its star as seen from Earth. Radial velocity measurements would help determine the most efficient and time-effective means of observing potential planetary transits.
Radial velocity measurements revealed the existence of a planet with a mass of at least 7 Earths. This planet, GJ 3634 b
GJ 3634 b
GJ 3634 b is a Super-Earth in the orbit of the nearby red dwarf GJ 3634. The planet is approximately eight times the mass of Earth, and orbits its star every two and a half days at a distance of .0287 AU...
, became the first planet to be discovered under the new strategy. The team of astronomers then followed up with transit measurements using instruments on 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...
; they found that there was most likely no transit event present at the star, but they were able to discover its true mass. GJ 3634 b was published to 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 February 8, 2011.
Characteristics
GJ 3634 is an M-type red dwarfRed dwarf
According to the Hertzsprung-Russell diagram, a red dwarf star is a small and relatively cool star, of the main sequence, either late K or M spectral type....
, a cool, small and dim star that shines with reddish light. It lies in the Hydra
Hydra (constellation)
Hydra is the largest of the 88 modern constellations, measuring 1303 square degrees. It has a long history, having been included among the 48 constellations listed by the 2nd century astronomer Ptolemy. It is commonly represented as a water snake...
constellation. The star is 45% 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, and is 43% the Sun's size. GJ 3634, described by its discoverers as an "intermediately active star," has a luminosity
Luminosity
Luminosity is a measurement of brightness.-In photometry and color imaging:In photometry, luminosity is sometimes incorrectly used to refer to luminance, which is the density of luminous intensity in a given direction. The SI unit for luminance is candela per square metre.The luminosity function...
of 0.02, meaning that it releases about 2% of the energy that the Sun radiates. The star is relatively metal-poor; with a 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, GJ 3634 has 79% the amount of iron that has been measured in the Sun. The star is younger than the Sun, with an estimated age of at most three billion years.
GJ 3634 has 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 11.95. Thus, despite its proximity at 19.8 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 (64.6 light years) away from the Earth, it cannot be seen with the unaided eye. The star is of a similar distance from Earth as planet-bearing 51 Pegasi
51 Pegasi
51 Pegasi is a Sun-like star located 15.6 parsecs from Earth in the constellation Pegasus...
, which lies at a distance of 14.7 parsecs (47.95 light years).
Planetary system
GJ 3634 has one confirmed planet in orbit: GJ 3634 bGJ 3634 b
GJ 3634 b is a Super-Earth in the orbit of the nearby red dwarf GJ 3634. The planet is approximately eight times the mass of Earth, and orbits its star every two and a half days at a distance of .0287 AU...
. The planet was called a Super-Earth
Super-Earth
A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below the mass of the Solar System's gas giants. The term super-Earth refers only to the mass of the planet, and does not imply anything about the surface conditions or habitability...
by its discoverers because of its mass, which was deduced to be 8.4 times that of Earth's and 0.02 times that of Jupiter's. GJ 3634 b has an extremely 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...
, orbiting GJ 3634 every 2.64561 days. The planet orbits near to its star, and is at an average distance of .0287 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
away. It has an orbital 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 0.08, meaning that its orbit is very circular.
The initial study into the system suggests that a second planet in the inner system is unlikely. The discoverers of GJ 3634 b, however, noted the signal of a secondary body of an unknown nature that most likely orbits GJ 3634 every 200 days with a mass that is at most double that of Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...
.