Beta Pictoris Moving Group
Encyclopedia
The Beta Pictoris Moving Group is a young moving group of star
s located relatively near Earth
. A moving group, in astronomy
, is a group of stars that share a common motion through space as well as a common origin. This moving group is named for Beta Pictoris
.
The Beta Pictoris Moving Group is an important object for astronomical study as it is the closest youthful group of stars to the Earth. The star Beta Pictoris
is known to have a large disk of gas and dust, possibly a protoplanetary disk
. There is also evidence of a young gas giant
planet around the star. The age and distance of the group makes it a candidate for directly imaging
extrasolar planet
s.
s. The core of the group is located some 115 light-year
s from Earth, and has an average estimated age of between 10 and 30 million years.
The majority of the group is made up of cool, dim K and M class
stars. Most are not visible to the naked eye. The members that are visible to the naked eye are:
The group covers a region of space for the most part visible only in the Southern Hemisphere
, and lies in the constellations Eridanus
, Lepus
, Pictor
, Scorpius
, Fornax
, Triangulum Australe
and Telescopium
.
, extremely young stars of this age should be located near other young stars that formed from the same region in space. It is not until significantly later that gravitational interactions with other stars causes stellar 'siblings' to disperse.
In 1999 the situation was resolved by the discovery of a pair of dim red dwarf
stars were discovered to have a similar velocity and age to β Pictoris, lending credence to the estimated age of the star.
Further work published in 2001 identified a total of 17 stellar systems with a similar motion and age as the Beta Pictoris moving group, named for the primary member of the association.
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
s located relatively near 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...
. A moving group, in astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
, is a group of stars that share a common motion through space as well as a common origin. This moving group is named for Beta Pictoris
Beta Pictoris
Beta Pictoris is the second brightest star in the constellation Pictor. It is located 63.4 light years from our solar system, and is 1.75 times as massive and 8.7 times as luminous as the Sun. The Beta Pictoris system is very young, only 8–20 million years old, although it is already in the main...
.
The Beta Pictoris Moving Group is an important object for astronomical study as it is the closest youthful group of stars to the Earth. The star Beta Pictoris
Beta Pictoris
Beta Pictoris is the second brightest star in the constellation Pictor. It is located 63.4 light years from our solar system, and is 1.75 times as massive and 8.7 times as luminous as the Sun. The Beta Pictoris system is very young, only 8–20 million years old, although it is already in the main...
is known to have a large disk of gas and dust, possibly a protoplanetary disk
Protoplanetary disk
A protoplanetary disk is a rotating circumstellar disk of dense gas surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star...
. There is also evidence of a young gas giant
Gas giant
A gas giant is a large planet that is not primarily composed of rock or other solid matter. There are four gas giants in the Solar System: Jupiter, Saturn, Uranus, and Neptune...
planet around the star. The age and distance of the group makes it a candidate for directly imaging
Methods of detecting extrasolar planets
Any planet is an extremely faint light source compared to its parent star. In addition to the intrinsic difficulty of detecting such a faint light source, the light from the parent star causes a glare that washes it out...
extrasolar planet
Extrasolar 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...
s.
Constituents
The Beta Pictoris Moving Group consists of 17 stellar systems, comprising a total of 28 individual component stars, including identified brown dwarfBrown 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...
s. The core of the group is located some 115 light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s from Earth, and has an average estimated age of between 10 and 30 million years.
The majority of the group is made up of cool, dim K and M class
Stellar 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...
stars. Most are not visible to the naked eye. The members that are visible to the naked eye are:
- Beta PictorisBeta PictorisBeta Pictoris is the second brightest star in the constellation Pictor. It is located 63.4 light years from our solar system, and is 1.75 times as massive and 8.7 times as luminous as the Sun. The Beta Pictoris system is very young, only 8–20 million years old, although it is already in the main...
- Eta TelescopiiEta TelescopiiEta Telescopii is a star in the constellation Telescopium.Eta Telescopii is a white A-type main sequence dwarf with an apparent magnitude of +5.03. It is approximately 155 light years from Earth and is a member of the Beta Pictoris Moving Group....
- 51 Eridani
- HD 203
- HD 146624
- HD 165189
- HD 172555HD 172555HD 172555 is a white-hot A5V star located relatively close by, 95 light years from Earth in the direction of the constellation Pavo. Spectrographic evidence indicates a relatively recent collision between two planet-sized bodies that destroyed the smaller of the two, which was about the size of...
- Beta Trianguli AustralisBeta Trianguli AustralisBeta Trianguli Australis is a binary star in the constellation Triangulum Australe. It is approximately 40.1 light years from Earth....
- Kappa Fornacis
The group covers a region of space for the most part visible only in the Southern Hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...
, and lies in the constellations Eridanus
Eridanus (constellation)
Eridanus is a constellation. It is represented as a river; its name is the Ancient Greek name for the Po River. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations. It is the sixth largest of the modern...
, Lepus
Lepus (constellation)
Lepus is a constellation lying just south of the celestial equator, immediately south of Orion. Its name is Latin for hare. Although the hare does not represent any particular figure in Greek mythology, Lepus was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it...
, Pictor
Pictor
Pictor is a small and faint constellation in the southern sky , located between the brilliant star Canopus and the Large Magellanic Cloud. Its name is Latin for painter, but it is in fact an abbreviation of its original name Equuleus Pictoris, the 'painter's easel', and it is normally represented...
, Scorpius
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...
, Fornax
Fornax
Fornax is a constellation in the southern sky. Its name is Latin for furnace. It was created in the 18th century and is now one of the 88 modern constellations.-History:Fornax was formed by Nicolas Louis de Lacaille in 1756...
, Triangulum Australe
Triangulum Australe
Triangulum Australe is a small constellation in the southern sky, created in the sixteenth century. Its name is Latin for 'the southern triangle', which distinguishes it from Triangulum in the northern sky...
and Telescopium
Telescopium
Telescopium is a minor southern constellation created in the 18th century by Nicolas Louis de Lacaille, a French astronomer and student of the southern skies. Its name is a Latinized form of the Greek word for telescope....
.
Discovery
An early estimated age for the star Beta Pictoris at about 10 million years proved problematic due to the star's apparent isolation in space. According to current theory regarding stellar evolutionStellar evolution
Stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime. Depending on the mass of the star, this lifetime ranges from only a few million years to trillions of years .Stellar evolution is not studied by observing the life of a single...
, extremely young stars of this age should be located near other young stars that formed from the same region in space. It is not until significantly later that gravitational interactions with other stars causes stellar 'siblings' to disperse.
In 1999 the situation was resolved by the discovery of a pair of 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 were discovered to have a similar velocity and age to β Pictoris, lending credence to the estimated age of the star.
Further work published in 2001 identified a total of 17 stellar systems with a similar motion and age as the Beta Pictoris moving group, named for the primary member of the association.