ν Octantis, Latinised as Nu Octantis, is a spectroscopic binary star in the constellation

Octans Octans () is a faint constellation located in the deep Southern Sky. Its name is Latin for the eighth part of a circle, but it is named after the octant, a navigational instrument. Devised by French astronomer Nicolas Louis de Lacaille in 1752 ...

with a period around 2.9 years. Its apparent magnitude is 3.73. Located around distant, the primary is an

orange giant A giant star is a star with substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature.Giant star, entry in ''Astronomy Encyclopedia'', ed. Patrick Moore, New York: Oxford University Press ...

of spectral type K1III, a star that has used up its core

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...

and has expanded. The secondary star is likely either a red dwarf or a

white dwarf A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes ...

, from its relatively low mass.

Planetary system

In 2009, the system was hypothesised to contain a superjovian exoplanet based on perturbations in the orbital period. A prograde solution was quickly ruled out but a retrograde solution remains a possibility, although the variations may instead be due to the secondary star being itself a close binary, since the formation of a planet in such a system would difficult due to dynamic perturbations. Further evidence ruling out a stellar variability and favouring the existence of the planet was gathered by 2021.

References

{{DEFAULTSORT:Nu Octantis Octans K-type giants Spectroscopic binaries Octantis, Nu CD-77 1079 107089 8254 205478 Gliese and GJ objects Hypothetical planetary systems