Beta Tucanae

Beta Tucanae, Latinized from β Tucanae, is a group of six stars which appear to be at least loosely bound into a system in the constellation Tucana. Three of the stars are luminous and distinct enough to have been given their own Bayer designations, β¹ Tucanae through β³ Tucanae. The system is approximately 140 light years from Earth.

β^{1, 2} Tucanae

The two brightest stars, Beta¹ Tucanae and Beta² Tucanae, also referred to as Beta Tucanae A (or AB) and Beta Tucanae C (or CD), are 27 arcseconds, or at least 1100 astronomical units (AU) apart. They are both main sequence dwarfs, Beta¹ a blue-white B-type star with an apparent magnitude of +4.36, and Beta² a white A-type star with an apparent magnitude of +4.53.

Both of these bright stars are binaries. Beta Tucanae B is a magnitude +13.5 star which is a close companion to Beta¹, being 2.4 arcseconds, or at least 100 AU away. Beta Tucanae C is a close binary of components Ca and Cb, separated by 0.6 AU. The 6th magnitude Beta Tucanae D, is another A-type star which is separated by approximately 0.38 arcseconds (16 AU) from Beta Tucanae C.

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Hierarchy of orbits in the β Tucanae system </div>

β³ Tucanae

Beta³ Tucanae is a suspected binary star which is separated from Beta¹ and Beta² Tucanae by 9 arcminutes on the sky, which puts the two systems at least 23&nbsp;000 astronomical units (AU) or 0.37 light years apart. It is not clear how tightly Beta³ 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.

In 1926, Beta³ Tucanae was reported to be a binary, with two components of magnitudes 5.7 and 6.1 separated by , although more recent observations could not confirm this. At the separation of they would be separated by at least .

Beta³ Tucanae has an infrared excess, suggesting the presence a debris disk around the primary star.

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