Gliese 667
Encyclopedia
Gliese 667 is a triple star system in the constellation of Scorpius
. The star system lies at a distance of about 6.8 pc
(22.1 ly). There is a 12th magnitude star close to the other three, but it is not gravitationally bound to the system. To the naked eye, the system appears to be a single faint star of magnitude 5.89.
The system has a relatively high proper motion, exceeding 1 second of arc per year.
, but have an eccentric orbit, which takes them as close as about 5 AU, or as far as 20 AU. The orbit takes approximately 42.15 years to complete. The orbital distance translates to an average separation of 1.8".
Gl 667 C orbits further out, between about 56 and 215 AU, equating to an angular separation of about 30".
K3V. The star has a lower concentration of heavy elements (metals) than the Sun
. The star has a mass of around 75% of that of the Sun and a visual luminosity of around 12 or 13% of that of the Sun. The apparent magnitude
is 6.29, giving an absolute magnitude
of around 7.07.
of around 8.02.
, Gliese 667 Cb and Gliese 667 Cc, have been found orbiting Gliese 667 C. The planets have masses of at least 6.0 and 3.9 times the mass of Earth
, respectively, (and are thus classified as super-Earths
). Planet Cb has an orbital period of approximately one week at a semimajor axis of 0.05 AU
, while planet Cc orbits the star every four weeks at a distance of 0.28 AU. Planet Cb planet was announced by HARPS on October 19, 2009, together with 29 other planets, while Cc was included in a paper published on November 21, 2011. A discovery paper is in preparation.
Scorpius
Scorpius, sometimes known as Scorpio, is one of the constellations of the zodiac. Its name is Latin for scorpion, and its symbol is . It lies between Libra to the west and Sagittarius to the east...
. The star system lies at a distance of about 6.8 pc
Parsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
(22.1 ly). There is a 12th magnitude star close to the other three, but it is not gravitationally bound to the system. To the naked eye, the system appears to be a single faint star of magnitude 5.89.
The system has a relatively high proper motion, exceeding 1 second of arc per year.
Star system
The two brightest components, Gl 667 A and Gl 667 B, are separated by an average distance of about 12.6 AUAstronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
, but have an eccentric orbit, which takes them as close as about 5 AU, or as far as 20 AU. The orbit takes approximately 42.15 years to complete. The orbital distance translates to an average separation of 1.8".
Gl 667 C orbits further out, between about 56 and 215 AU, equating to an angular separation of about 30".
Gliese 667 A
Gliese 667 A is an orange dwarf star of spectral classStellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...
K3V. The star has a lower concentration of heavy elements (metals) than 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...
. The star has a mass of around 75% of that of the Sun and a visual luminosity of around 12 or 13% of that of the Sun. The 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...
is 6.29, giving an absolute magnitude
Absolute magnitude
Absolute magnitude is the measure of a celestial object's intrinsic brightness. it is also the apparent magnitude a star would have if it were 32.6 light years away from Earth...
of around 7.07.
Gliese 667 B
Gliese 667 B is an orange dwarf star of spectral class K5V, with a mass of about 65% of that of the Sun, and only about 5% of the Sun's visual luminosity. The apparent magnitude is 7.24, giving an absolute magnitudeAbsolute magnitude
Absolute magnitude is the measure of a celestial object's intrinsic brightness. it is also the apparent magnitude a star would have if it were 32.6 light years away from Earth...
of around 8.02.
Gliese 667 C
Gliese 667 C is a red dwarf star of spectral class of M2V. It has a mass of around 38% of that of the Sun and only 0.3% of the Sun's visual luminosity. The apparent magnitude is 10.25, giving an absolute magnitude of around 11.03.Planetary system
Two extrasolar planetsExtrasolar 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...
, Gliese 667 Cb and Gliese 667 Cc, have been found orbiting Gliese 667 C. The planets have masses of at least 6.0 and 3.9 times the mass of 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...
, respectively, (and are thus classified as super-Earths
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...
). Planet Cb has an orbital period of approximately one week at a semimajor axis of 0.05 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
, while planet Cc orbits the star every four weeks at a distance of 0.28 AU. Planet Cb planet was announced by HARPS on October 19, 2009, together with 29 other planets, while Cc was included in a paper published on November 21, 2011. A discovery paper is in preparation.