Theta
2 Crucis,
Latinized from θ
2 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