Magnitude 5.02 Apparent magnitude (V) 5.02 | Constellation Columba | |
Similar Mu Columbae, Alpha Columbae, Iota Boötis | ||
Theta Columbae is a solitary star in the southern constellation of Columba. It is faintly visible to the naked eye, having an apparent visual magnitude of 5.02. Based upon an annual parallax shift of just 4.52 mas, it lies roughly 720 light years from the Sun. At that distance, the visual magnitude of the star is reduced by an interstellar extinction factor of 0.11. It is currently moving away from the Sun with a radial velocity of 45.3 km/s. The star made its closest approach about 4.7 million years ago when it underwent perihelion passage at a distance of 10.9 ly (3.33 pc).
For ancient Arabian astronomers, this star, along with ζ CMa, λ CMa, γ Col, δ Col, κ Col, λ Col, μ Col and ξ Col, formed Al Ḳurūd (ألقرد - al-qird), the Apes. In Chinese, 孫 (Sūn), meaning Grandson, refers to an asterism consisting of θ Columbae and κ Columbae. Consequently, θ Columbae itself is known as 孫二 (Sūn èr, English: the Second Star of Grandson.).
This is an evolving B-type subgiant star with a stellar classification of B8 IV, having recently left the main sequence. It is spinning rapidly with a projected rotational velocity of 249 km/s. The star has an estimated four times the mass of the Sun. It radiates 472 times the solar luminosity from its outer atmosphere at an effective temperature of 9,916 K.