GJ 3634 b
Encyclopedia
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 the first to be discovered by a group of astronomers searching for exoplanets in the orbit of very-low-mass stars after the team reorganized their strategy, choosing to search for targets that they could also confirm using the transit method. However, a transit event associated with GJ 3634 b was not detected. The planet's discovery was published in Astronomy and Astrophysics
on February 8, 2011.
(HARPS) at La Silla Observatory
in Chile, six years of radial velocity data led the astronomers in the discovery of eleven other planets. After these discoveries, the astronomers chose to refocus their search on short-period planets, hoping to follow up after discoveries using the radial velocity method with a search for planets that also transited, or crossed in front of, their host stars as seen from Earth.
The search for GJ 3634 b started with a single exposure taken with HARPS on March 25, 2009. The results helped verify that GJ 3634 was an ideal target for a planet search using the radial velocity method (in which the gravitational pull of a planet on its star is measured by observing the resulting Doppler shift), as stellar activity would not overly mask or mimic Doppler spectroscopy
measurements. It was also confirmed that GJ 3634 neither a binary star nor a quickly rotating star, common false positives when searching for transiting planets. GJ 3634 was observed two weeks later for ten consecutive nights. Analysis of the resulting data found that the radial velocity variations most likely indicated the existence of a planet.
Having discovered the planet, the astronomers worked to discover a transit event using the Infrared Array Camera
of the Spitzer Space Telescope
, as ground-based observations could prove difficult if GJ 3634 b was a rocky planet. While the observations did not suggest that GJ 3634 b transited its star, a few orbital parameters were discovered, yielding the planet's true mass, which cannot be collected solely by radial velocity measurements.
The discovery of GJ 3634 b was reported in the journal Astronomy and Astrophysics
on February 8, 2011. GJ 3634 b was the first planet discovered by the astronomers after adopting their new strategy, despite their failure to find a transit event for the planet.
, meaning that it is small, emits reddish light, and has a relatively low temperature for a star. The star is 0.45 times the mass
of and 0.43 times the radius of the Sun. GJ 3634 is 0.020 times as luminous as the Sun, meaning that it radiates about 2% of the amount of energy that the Sun does. It was described as an intermediately active star in its discovery paper. GJ 3634 lies 19.8 parsec
s (approximately 64.6 light years) away from Earth, a relatively close star. GJ 3634 b is the only planet to have been confirmed in the star's orbit, although initial analysis of the data suggests that a secondary body of an unknown nature also exists, with an orbit of more than 200 days and a mass approximately twice that of Neptune's.
The star was first catalogued in 1987, and was referenced on no more than five other occasions between its discovery and that of GJ 3634 b. The prefix "GJ" comes from the Gliese-Jahreiß catalogue
, which documents stars within twenty parsecs of Earth.
GJ 3634 has an apparent magnitude
of 11.95. It cannot be seen with the naked eye
.
GJ 3634 b is estimated to be 8.4 times the mass of Earth, or 0.02 times the mass of Jupiter. It has a very short orbital period
, and circles its host star every 2.64561 days at a distance of 0.0287 AU
. GJ 3634 b has an eccentricity
of 0.08, giving it a mostly circular orbit. In comparison, planet Mercury
lies 0.387 AU from the Sun, orbits every 87.97 days, and has an orbital eccentricity of 0.2056.
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...
in the orbit of the nearby red dwarf GJ 3634
GJ 3634
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 parsecs . It was targeted by...
. 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 the first to be discovered by a group of astronomers searching for exoplanets in the orbit of very-low-mass stars after the team reorganized their strategy, choosing to search for targets that they could also confirm using the transit method. However, a transit event associated with GJ 3634 b was not detected. The planet's discovery was published in 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.
Discovery
GJ 3634 was one of a sample of over 300 very-low-mass stars targeted by astronomers in search of planets that may orbit such stars. Using the High Accuracy Radial Velocity Planet SearcherHigh 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 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, six years of radial velocity data led the astronomers in the discovery of eleven other planets. After these discoveries, the astronomers chose to refocus their search on short-period planets, hoping to follow up after discoveries using the radial velocity method with a search for planets that also transited, or crossed in front of, their host stars as seen from Earth.
The search for GJ 3634 b started with a single exposure taken with HARPS on March 25, 2009. The results helped verify that GJ 3634 was an ideal target for a planet search using the radial velocity method (in which the gravitational pull of a planet on its star is measured by observing the resulting Doppler shift), as stellar activity would not overly mask or mimic 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....
measurements. It was also confirmed that GJ 3634 neither a binary star nor a quickly rotating star, common false positives when searching for transiting planets. GJ 3634 was observed two weeks later for ten consecutive nights. Analysis of the resulting data found that the radial velocity variations most likely indicated the existence of a planet.
Having discovered the planet, the astronomers worked to discover a transit event using the Infrared Array Camera
Spitzer Space Telescope
The Spitzer Space Telescope , formerly the Space Infrared Telescope Facility is an infrared space observatory launched in 2003...
of 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...
, as ground-based observations could prove difficult if GJ 3634 b was a rocky planet. While the observations did not suggest that GJ 3634 b transited its star, a few orbital parameters were discovered, yielding the planet's true mass, which cannot be collected solely by radial velocity measurements.
The discovery of GJ 3634 b was reported 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 February 8, 2011. GJ 3634 b was the first planet discovered by the astronomers after adopting their new strategy, despite their failure to find a transit event for the planet.
Host star
GJ 3634 is a M-class dwarf starDwarf star
The term dwarf star refers to a variety of distinct classes of stars.* Dwarf star alone generally refers to any main sequence star, a star of luminosity class V.** Red dwarfs are low-mass main sequence stars....
, meaning that it is small, emits reddish light, and has a relatively low temperature for a star. The star is 0.45 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 and 0.43 times the radius of the Sun. GJ 3634 is 0.020 times as luminous as the Sun, meaning that it radiates about 2% of the amount of energy that the Sun does. It was described as an intermediately active star in its discovery paper. GJ 3634 lies 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 (approximately 64.6 light years) away from Earth, a relatively close star. GJ 3634 b is the only planet to have been confirmed in the star's orbit, although initial analysis of the data suggests that a secondary body of an unknown nature also exists, with an orbit of more than 200 days and a mass approximately twice that of Neptune's.
The star was first catalogued in 1987, and was referenced on no more than five other occasions between its discovery and that of GJ 3634 b. The prefix "GJ" comes from the Gliese-Jahreiß catalogue
Gliese 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:...
, which documents stars within twenty parsecs of Earth.
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. It 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"...
.
Characteristics
Super-EarthSuper-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 is estimated to be 8.4 times the mass of Earth, or 0.02 times the mass of Jupiter. It has a very 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...
, and circles its host star every 2.64561 days at a distance of 0.0287 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
. GJ 3634 b 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 0.08, giving it a mostly circular orbit. 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...
lies 0.387 AU from the Sun, orbits every 87.97 days, and has an orbital eccentricity of 0.2056.