Theta2 Crucis
Encyclopedia
θ2 Crucis is a spectroscopic binary star
in the constellation
Crux
. This pair of stars complete an orbit
every 3.4280 days and they have a low orbital eccentricity
that is close to 0.0. θ2 Crucis is located at about 750 light-year
s from the Sun
.
The system has a combined mean apparent magnitude
of +4.72m. Since a member of the system is a β Cephei-type
variable star
, the magnitude is not fixed but varies slightly between +4.70m and +4.74m. The period of this variability is 0.0889 days. The system is categorized as is a blue-white subgiant with a stellar classification
of B2 IV.
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...
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....
Crux
Crux
Crux is the smallest of the 88 modern constellations, but is one of the most distinctive. Its name is Latin for cross, and it is dominated by a cross-shaped asterism that is commonly known as the Southern Cross.-Visibility:...
. This pair of stars complete an orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
every 3.4280 days and they have a low orbital eccentricity
Orbital eccentricity
The orbital eccentricity of an astronomical body is the amount by which its orbit deviates from a perfect circle, where 0 is perfectly circular, and 1.0 is a parabola, and no longer a closed orbit...
that is close to 0.0. θ2 Crucis is located at about 750 light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s from the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
.
The system has a combined mean 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 +4.72m. Since a member of the system is a β Cephei-type
Beta Cephei variable
Beta Cephei variables are variable stars which exhibit variations in their brightness due to pulsations of the stars' surfaces. The point of maximum brightness roughly corresponds to the maximum contraction of the star. Typically, Beta Cephei variables change in brightness by 0.01 to 0.3...
variable star
Variable star
A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth...
, the magnitude is not fixed but varies slightly between +4.70m and +4.74m. The period of this variability is 0.0889 days. The system is categorized as is a blue-white subgiant with a stellar classification
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...
of B2 IV.