Zeta Octantis
# Zeta Octantis

Zeta Octantis, Latinized from ζ Octantis, is a solitary, yellowish-white hued star located in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.42, making it faintly visible to the naked eye under ideal conditions. The star is located relatively close at a distance of only 156 light-years based on Gaia DR3 parallax measurements, but is drifting closer with a radial velocity of −3.6 km/s. At its current distance, Zeta Octantis' brightness is diminished by 0.25 magnitudes due to interstellar dust.

This s an evolved A-type star with a stellar classification of A8/9 IV. David S. Evans and colleagues, however, give it a classification of F0 III, which suggests it is already an evolved giant star. It has double the Sun's mass, and 2.25 times the Sun's radius. It radiates around 13 times the luminosity of the Sun from its photosphere at an effective temperature of 7,063 K. Zeta Octantis is estimated to be 1.25 billion years olds based on stellar evolution models by Trevor J. David and Lynne A. Hillenbrand. It has a low metallicity, having only 44% the abundance of heavy metals compared to the Sun. Despite its advanced age, the object spins rapidly with a projected rotational velocity of 115 km/s, resulting in an oblate shape with a equatorial bulge 11% larger than the polar radius.

