Beta Tucanae
Encyclopedia
Beta Tucanae is a group of six star
s which appear to be at least loosely bound into a system
in the constellation
Tucana
. Three of the stars are luminous enough to have been given their own Bayer designation
s, β¹ Tucanae through β³ Tucanae. The system is approximately 140 light years
from Earth
.
s (AU) apart. They are both main sequence dwarf
s, Beta-1 a blue-white B-type
star with an apparent magnitude
of +4.36, and Beta-2 a white A-type
star with an apparent magnitude
of +4.53.
Both of these bright stars have at least one closer main sequence companion. Beta Tucanae B is a magnitude +13.5 A-type star which is a close companion to Beta-1, being 2.4 arcseconds, or at least 100 AU away. Beta-2's companion, the 6th magnitude Beta Tucanae D, is another A-type star which is separated by approximately 0.38 arcseconds (16 AU) from Beta-2.
which is separated from Beta-1 and Beta-2 Tucanae by 9 arcminutes on the sky, which puts the two systems at least 23 000 astronomical unit
s (AU) or 0.37 light years apart. It's not clear how tightly Beta-3 Tucanae is gravitationally bound to the rest of the β Tucanae system, but all the stars have similar distances from Earth and have the same proper motion
on the sky, indicating they are gravitationally influencing each other to some degree.
Both components of the binary system are white A-type
main sequence dwarf
s and they have apparent magnitude
s of +5.8 and +6.0. They are separated by 0.1 arcseconds, or at least 4 astronomical unit
s.
Considering Beta-1a to be the central star, its binary companion, Beta-1b, orbits at a bit over three times Neptune's distance from the Sun. The Beta-2 pair is located over ten times further away. The pair is separated by less than the distance from the Sun to Uranus. The Beta-3 pair is much further out, at one-and-a-half times the distance of Proxima Centauri
from the main Alpha Centauri
pair. The Beta-3 pair are separated by less distance than the Sun and Jupiter.
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 which appear to be at least loosely bound into a 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...
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....
Tucana
Tucana
Tucana is a constellation in the southern sky, created in the late sixteenth century. Its name is Latin for the toucan, a South American bird.-History:...
. Three of the stars are luminous enough to have been given their own Bayer designation
Bayer designation
A Bayer designation is a stellar designation in which a specific star is identified by a Greek letter, followed by the genitive form of its parent constellation's Latin name...
s, β¹ Tucanae through β³ Tucanae. The system is approximately 140 light years
Light Years
Light Years is the seventh studio album by Australian recording artist Kylie Minogue. It was released on 25 September 2000 by Parlophone and Mushroom Records. The album's style was indicative of her return to "mainstream pop dance tunes"....
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...
.
β¹,² Tucanae
The two brightest stars, Beta-1 Tucanae and Beta-2 Tucanae, also referred to as Beta Tucanae A and Beta Tucanae C, are 27 arcseconds, or at least 1100 astronomical unitAstronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
s (AU) apart. They are both main sequence dwarf
Main sequence
The main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell...
s, Beta-1 a blue-white B-type
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...
star with 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 +4.36, and Beta-2 a white A-type
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...
star with 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 +4.53.
Both of these bright stars have at least one closer main sequence companion. Beta Tucanae B is a magnitude +13.5 A-type star which is a close companion to Beta-1, being 2.4 arcseconds, or at least 100 AU away. Beta-2's companion, the 6th magnitude Beta Tucanae D, is another A-type star which is separated by approximately 0.38 arcseconds (16 AU) from Beta-2.
β³ Tucanae
Beta-3 Tucanae is a binary starBinary 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...
which is separated from Beta-1 and Beta-2 Tucanae by 9 arcminutes on the sky, which puts the two systems at least 23 000 astronomical unit
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
s (AU) or 0.37 light years apart. It's not clear how tightly Beta-3 Tucanae is gravitationally bound to the rest of the β Tucanae system, but all the stars have similar distances from Earth and have the same 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...
on the sky, indicating they are gravitationally influencing each other to some degree.
Both components of the binary system are white A-type
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...
main sequence dwarf
Main sequence
The main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell...
s and they have 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...
s of +5.8 and +6.0. They are separated by 0.1 arcseconds, or at least 4 astronomical unit
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
s.
β Tucanae system
The stars in the system are poorly named, as their designations violate the convention for multiple stars. Beta-2 should be component B, but is C, while Beta-3 should be C, but is B.Considering Beta-1a to be the central star, its binary companion, Beta-1b, orbits at a bit over three times Neptune's distance from the Sun. The Beta-2 pair is located over ten times further away. The pair is separated by less than the distance from the Sun to Uranus. The Beta-3 pair is much further out, at one-and-a-half times the distance of Proxima Centauri
Proxima Centauri
Proxima Centauri is a red dwarf star about 4.2 light-years distant in the constellation of Centaurus. It was discovered in 1915 by Robert Innes, the Director of the Union Observatory in South Africa, and is the nearest known star to the Sun, although it is too faint to be seen with the naked eye...
from the main Alpha Centauri
Alpha Centauri
Alpha Centauri is the brightest star in the southern constellation of Centaurus...
pair. The Beta-3 pair are separated by less distance than the Sun and Jupiter.