Beta Tucanae, Latinized from β Tucanae, is a group of six

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

s which appear to be at least loosely bound into a

system A system is a group of Interaction, interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment (systems), environment, is described by its boundaries, ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Tucana Tucana (The Toucan) is a constellation of stars in the southern sky, named after the toucan, a South American bird. It is one of twelve constellations conceived in the late sixteenth century by Petrus Plancius from the observations of Pieter D ...

. Three of the stars are luminous and distinct enough to have been given their own

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars. ...

s, β¹ Tucanae through β³ Tucanae. The system is approximately 140

light years A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

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

arcsecond A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...

s, or at least 1100

astronomical unit The astronomical unit (symbol: au, or or AU) is a unit of length, roughly the distance from Earth to the Sun and approximately equal to or 8.3 light-minutes. The actual distance from Earth to the Sun varies by about 3% as Earth orbits t ...

s (AU) apart. They are both main sequence dwarfs, Beta-1 a blue-white B-type star with an

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

of +4.36, and Beta-2 a white A-type star with an

of +4.53. Both of these bright stars have at least one closer main sequence companion. Beta Tucanae B is a magnitude +13.5 M3-type star which is a close companion to Beta-1, being 2.4

s, 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

s (16 AU) from Beta-2.

β³ Tucanae

Beta-3 Tucanae is a

binary star A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...

which is separated from Beta-1 and Beta-2 Tucanae by 9

arcminute A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...

s on the sky, which puts the two systems at least 23 000

s (AU) or 0.37

light year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s apart. It is 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 is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more dista ...

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 star Main may refer to: Geography * Main River (disambiguation) **Most commonly the Main (river) in Germany *Main, Iran, a village in Fars Province *"Spanish Main", the Caribbean coasts of mainland Spanish territories in the 16th and 17th centuries * ...

s and they have

s of +5.8 and +6.0. They are separated by 0.1

s, or at least 4

s. Beta-3 Tucanae has an

infrared excess An infrared excess is a measurement of an astronomical source, typically a star, that in their spectral energy distribution has a greater measured infrared flux than expected by assuming the star is a blackbody radiator. Infrared excesses are o ...

, suggesting the presence a

debris disk A debris disk (American English), or debris disc (Commonwealth English), is a circumstellar disk of dust and debris in orbit around a star. Sometimes these disks contain prominent rings, as seen in the image of Fomalhaut on the right. Debris dis ...

around the primary star. The distance of the other star to the debris disk is not known.

β Tucanae system

Beta-1a's 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 is a small, low-mass star located away from the Sun in the southern constellation of Centaurus. Its Latin name means the 'nearest tarof Centaurus'. It was discovered in 1915 by Robert Innes and is the nearest-kno ...

from the main

Alpha Centauri Alpha Centauri ( Latinized from α Centauri and often abbreviated Alpha Cen or α Cen) is a triple star system in the constellation of Centaurus. It consists of 3 stars: Alpha Centauri A (officially Rigil Kentaurus), Alpha Centaur ...

pair. The Beta-3 pair are separated by less distance than the Sun and Jupiter.

References

{{DEFAULTSORT:Beta Tucanae B-type main-sequence stars A-type main-sequence stars Binary stars 6 Tucana (constellation) Tucanae, Beta Durchmusterung objects 002884 2885 3003 002484 487 578 0126 36

β¹,² Tucanae

β³ Tucanae

β Tucanae system

References

β¹^,² Tucanae