Luyten 726-8
Encyclopedia
Luyten 726-8 is a binary
star system
that is one of Earth's nearest neighbors, at about 8.7 light years from Earth
in the constellation
Cetus
. Luyten 726-8B is also known under the variable star designation UV Ceti, being the archetype for the class of flare star
s.
in the course of compiling a catalog of stars of high proper motion
; he noted its exceptionally high proper motion of 3.37 arc seconds annually and cataloged it as Luyten 726-8.
The two stars are of nearly equal brightness, with visual magnitudes of 12.57 and 11.99 as seen from Earth. They orbit one another every 26.5 years. The distance between the two stars varies from 2.1 AU. The Luyten 726-8 system is approximately 2.63 pc from Earth
's Solar System
, in the constellation
Cetus
, and is thus the sixth-closest star system to Earth. Its own nearest neighbor is Tau Ceti
, 0.88 pc away from it. If
km/s then approximately 28,700 years ago Luyten 726-8 was at its minimal distance of 2.21 pc
(7.2 ly) from the Sun.
and given the variable star designation BL Ceti. It is a red dwarf
of spectral type M5.5e. It is also a flare star, and classified as a UV Ceti variable type, but it is not nearly as remarkable or extreme in its behavior as its companion star UV Ceti. BL Ceti is also known as G 272-061.
of spectral type M6.0e.
at the minimal distance of about 0.93 ly
. Luyten 726-8 can penetrate a conjectured Oort cloud
about Epsilon Eridani, which may gravitationally perturb
some long-period comet
s. The duration of mutual transit of two star systems within 1 ly
from each other is about 4,600 years.
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...
star system
Star system
A star system or stellar system is a small number of stars which orbit each other, bound by gravitational attraction. A large number of stars bound by gravitation is generally called a star cluster or galaxy, although, broadly speaking, they are also star systems.-Binary star systems:A stellar...
that is one of Earth's nearest neighbors, at about 8.7 light years from 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...
in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Cetus
Cetus
Cetus is a constellation. Its name refers to Cetus, a sea monster in Greek mythology, although it is often called 'the whale' today. Cetus is located in the region of the sky that contains other water-related constellations such as Aquarius, Pisces, and Eridanus.-Ecliptic:Although Cetus is not...
. Luyten 726-8B is also known under the variable star designation UV Ceti, being the archetype for the class of flare star
Flare star
A flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare stars are analogous to solar flares in that they are due to magnetic reconnection in the atmospheres of the stars. The brightness increase is...
s.
Binary star system
The star system was discovered in 1948 by Willem Jacob LuytenWillem Jacob Luyten
Willem Jacob Luyten was a Dutch-American astronomer.-Life:Jacob Luyten was born in Semarang, Java, at the time part of the Dutch East Indies. His mother was Cornelia M. Francken and his father Jacob Luyten, a French teacher.At the age of 11 he observed Halley's comet, which started his...
in the course of compiling a catalog of stars of high proper motion
Proper motion
The proper motion of a star is its angular change in position over time as seen from the center of mass of the solar system. It is measured in seconds of arc per year, arcsec/yr, where 3600 arcseconds equal one degree. This contrasts with radial velocity, which is the time rate of change in...
; he noted its exceptionally high proper motion of 3.37 arc seconds annually and cataloged it as Luyten 726-8.
The two stars are of nearly equal brightness, with visual magnitudes of 12.57 and 11.99 as seen from Earth. They orbit one another every 26.5 years. The distance between the two stars varies from 2.1 AU. The Luyten 726-8 system is approximately 2.63 pc from 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...
's 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...
, in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Cetus
Cetus
Cetus is a constellation. Its name refers to Cetus, a sea monster in Greek mythology, although it is often called 'the whale' today. Cetus is located in the region of the sky that contains other water-related constellations such as Aquarius, Pisces, and Eridanus.-Ecliptic:Although Cetus is not...
, and is thus the sixth-closest star system to Earth. Its own nearest neighbor is Tau Ceti
Tau Ceti
Tau Ceti is a star in the constellation Cetus that is spectrally similar to the Sun, although it has only about 78% of the Sun's mass. At a distance of just under 12 light-years from the Solar System, it is a relatively close star. Tau Ceti is metal-deficient and so is thought to be less likely to...
, 0.88 pc away from it. If
km/s then approximately 28,700 years ago Luyten 726-8 was at its minimal distance of 2.21 pcParsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
(7.2 ly) from the Sun.
Luyten 726-8A (BL Ceti)
Luyten-726-8A was found to be a variable starVariable star
A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth...
and given the variable star designation BL Ceti. It is a red dwarf
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....
of spectral type M5.5e. It is also a flare star, and classified as a UV Ceti variable type, but it is not nearly as remarkable or extreme in its behavior as its companion star UV Ceti. BL Ceti is also known as G 272-061.
Luyten 726-8B (UV Ceti)
Soon after the discovery of Luyten 726-8A, the slightly brighter companion star Luyten 726-8B was discovered. Like Luyten 726-8A, this star was also found to be variable and given the variable star designation UV Ceti. Although UV Ceti was not the first flare star discovered, it is the most prominent example of such a star, now similar flare stars are classified as UV Ceti type variable stars. This star goes through fairly extreme changes of brightness: for instance, in 1952, its brightness increased by 75 times in only 20 seconds. UV Ceti is a 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....
of spectral type M6.0e.
Close encounters
In approximately 31,500 years, Luyten 726-8 will have a close encounter with Epsilon EridaniEpsilon Eridani
Epsilon Eridani is a star in the southern constellation Eridanus, along a declination 9.46° south of the celestial equator. This allows the star to be viewed from most of the Earth's surface. At a distance of 10.5 light years , it has an apparent magnitude of 3.73...
at the minimal distance of about 0.93 ly
Ly
Ly may refer to:* Ly the Fairy, a character from Rayman 2: The Great Escape* Lý Dynasty, a dynasty of Vietnam* Ly * Libya, ISO 3166-1 country code** .ly, the Top-level domain for Libya...
. Luyten 726-8 can penetrate a conjectured Oort cloud
Oort cloud
The Oort cloud , or the Öpik–Oort cloud , is a hypothesized spherical cloud of comets which may lie roughly 50,000 AU, or nearly a light-year, from the Sun. This places the cloud at nearly a quarter of the distance to Proxima Centauri, the nearest star to the Sun...
about Epsilon Eridani, which may gravitationally perturb
Perturbation (astronomy)
Perturbation is a term used in astronomy in connection with descriptions of the complex motion of a massive body which is subject to appreciable gravitational effects from more than one other massive body....
some long-period comet
Comet
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
s. The duration of mutual transit of two star systems within 1 ly
Ly
Ly may refer to:* Ly the Fairy, a character from Rayman 2: The Great Escape* Lý Dynasty, a dynasty of Vietnam* Ly * Libya, ISO 3166-1 country code** .ly, the Top-level domain for Libya...
from each other is about 4,600 years.
External links
- http://www.aavso.org/vstar/vsots/fall03.shtml
- http://www.solstation.com/stars/luy726-8.htm