GJ 412
Encyclopedia
Gliese 412 is a pair of stars that share a common proper motion
through space and are thought to form a binary star
system. The pair have an angular separation of 31.4″ at a position angle
of 126.1°. They are located 15.8 light years distant from the Sun
in the constellation
Ursa Major
. Both components are relatively dim red dwarf
stars.
The two stellar components of this system are currently separated by about 190 AU
. The primary has about 48% of the Sun's mass
, while the secondary is only 10%. The primary has a projected rotation
velocity at the equator
of less than 3 km/s. The secondary has a rotation velocity of .
The primary star was monitored for radial velocity
(RV) variations caused by a Jupiter-mass companion in a short period orbit. It displayed no significant excess of RV variation that could be attributed to a planet. A search of the system using near-infrared speckle interferometry also failed to detect a companion orbiting at distances of 1–10 AU. Nor was a brown dwarf
been detected orbiting within this system.
The space velocity components of this system are U = 141, V = –7 and W = 7. They are members of the halo population of the Milky Way
galaxy.
that is referred to as WX Ursae Majoris. It is characterized as a UV Ceti type variable star that displays infrequent increases in luminosity. This star was observed to flare as early as 1939 by the Dutch astronomer Adriaan van Maanen
.
Component B (WX Ursae Majoris) has been identified as an X-ray source, while no significant X-ray emission was detected from component A. This system had not been studied in X-rays prior to ROSAT
.
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...
through space and are thought to form a binary star
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...
system. The pair have an angular separation of 31.4″ at a position angle
Position angle
Position angle, usually abbreviated PA, is a measurement derived from observing visual binary stars. It is defined as the angular offset in degrees of the secondary star to the primary, relative to the north celestial pole....
of 126.1°. They are located 15.8 light years distant from 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...
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....
Ursa Major
Ursa Major
Ursa Major , also known as the Great Bear, is a constellation visible throughout the year in most of the northern hemisphere. It can best be seen in April...
. Both components are relatively dim 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....
stars.
The two stellar components of this system are currently separated by about 190 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
. The primary has about 48% of the Sun's mass
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
, while the secondary is only 10%. The primary has a projected rotation
Stellar rotation
Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface....
velocity at the equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
of less than 3 km/s. The secondary has a rotation velocity of .
The primary star was monitored for radial velocity
Radial velocity
Radial velocity is the velocity of an object in the direction of the line of sight . In astronomy, radial velocity most commonly refers to the spectroscopic radial velocity...
(RV) variations caused by a Jupiter-mass companion in a short period orbit. It displayed no significant excess of RV variation that could be attributed to a planet. A search of the system using near-infrared speckle interferometry also failed to detect a companion orbiting at distances of 1–10 AU. Nor was a brown dwarf
Brown dwarf
Brown dwarfs are sub-stellar objects which are too low in mass to sustain hydrogen-1 fusion reactions in their cores, which is characteristic of stars on the main sequence. Brown dwarfs have fully convective surfaces and interiors, with no chemical differentiation by depth...
been detected orbiting within this system.
The space velocity components of this system are U = 141, V = –7 and W = 7. They are members of the halo population of the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
galaxy.
X-ray source
The secondary is a flare starFlare 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...
that is referred to as WX Ursae Majoris. It is characterized as a UV Ceti type variable star that displays infrequent increases in luminosity. This star was observed to flare as early as 1939 by the Dutch astronomer Adriaan van Maanen
Adriaan Van Maanen
Adriaan van Maanen was a Dutch–American astronomer.Van Maanen, born into a well-to-do family in Friesland, studied astronomy at the University of Utrecht and worked briefly at the University of Groningen...
.
Component B (WX Ursae Majoris) has been identified as an X-ray source, while no significant X-ray emission was detected from component A. This system had not been studied in X-rays prior to ROSAT
ROSAT
ROSAT was a German Aerospace Center-led satellite X-ray telescope, with instruments built by Germany, the UK and the US...
.
See also
- List of nearest stars
- X-ray astronomyX-ray astronomyX-ray astronomy is an observational branch of astronomy which deals with the study of X-ray observation and detection from astronomical objects. X-radiation is absorbed by the Earth's atmosphere, so instruments to detect X-rays must be taken to high altitude by balloons, sounding rockets, and...