Theta² Crucis, Latinized from θ² Crucis, is a spectroscopic binary star in the constellation

Crux Crux () is a constellation of the southern sky that is centred on four bright stars in a cross-shaped asterism commonly known as the Southern Cross. It lies on the southern end of the Milky Way's visible band. The name ''Crux'' is Latin for ...

. This pair of stars complete an

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...

every 3.4280 days and they have a low orbital eccentricity that is close to 0.0. Theta² Crucis is located at about 690 light-years from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

. Since a member of the system is a β Cephei-type

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as e ...

, the magnitude is not fixed but varies slightly between +4.70 and +4.74. The period of this variability is 0.0889 days. The system is categorized as is a blue-white

B-type main sequence star A B-type main-sequence star (B V) is a main-sequence (hydrogen-burning) star of spectral type B and luminosity class V. These stars have from 2 to 16 times the mass of the Sun and surface temperatures between 10,000 and 30,000 K. B-type stars ...

with a stellar classification of B3 V, although it has also been classified as a

subgiant A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution ...

. Evolutionary models show it at a late stage of its main sequence life.

References

{{DEFAULTSORT:Theta2 Crucis Crucis, Theta2 Beta Cephei variables Crux Spectroscopic binaries B-type subgiants 4603 104841 058867 Durchmusterung objects