Alpha Octantis (Alpha Oct, α Octantis, α Oct) is a star

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....

 of Octans. It has an overall apparent visual magnitude of approximately 5.15 and is a spectroscopic binary star which consists of two giant star

Giant star

A giant star is a star with substantially larger radius and luminosity than a main sequence star of the same surface temperature. Typically, giant stars have radii between 10 and 100 solar radii and luminosities between 10 and 1,000 times that of the Sun. Stars still more luminous than giants are...

s, each with spectral type F, orbiting each other with a period of just over 9 days. The pair has also been classified as a Beta Lyrae-type

Beta Lyrae variable

Beta Lyrae variables are a class of close binary stars. Their total brightness is variable because the two component stars orbit each other, and in this orbit one component periodically passes in front of the other one, thereby blocking its light. The two component stars of Beta Lyrae systems are...

 eclipsing binary system.

External links

• Alpha Octantis, Jim Kaler, Stars.