HD 74180 is a single star in the constellation Vela. It is a yellow-white F-type supergiant with a mean apparent magnitude of +3.81 and a spectral classification F8Ib. Estimates of its distance to Earth vary between 3,200 and 8,300 light-years.
b Velorum has been classified as a suspected α Cygni variable star which varies by only 0.06 magnitude. There are possible periods near 53, 80, and 160 days, but the variation is largely irregular. It lies less than a degree from the small open cluster NGC 2645, but is not a member.
Several studies have considered b Velorum to be a highly luminous supergiant or hypergiant with an early F spectral type, for example F2 Ia+, F0 Ia,[1] and F4 I.[2] There were corresponding luminosity estimates of . A 2015 study used the Barbier-Chalonge-Divan (BCD) system to derive a luminosity of and a cooler less luminous F8 Ib spectral type.
Multiple papers give different distances for b Velorum. Bailer-Jones et al. (2021) give a distance of about 2530abbr=onNaNabbr=on. The Hipparcos spacecraft give a parallax of, translating into a distance of 1492.5pc. Aidelman et al. (2015) give a distance of 990pc. At the Hipparcos distance, bVelorum has its apparent brightness diminished by 1.11magnitudes due to interstellar extinction.
b Velorum has an angular diameter estimated at .[3] The physical size depends on the star's distance, and could be assuming the distance of Aidelman et al., assuming the Hipparcos distance, or even assuming the Bailer-Jones et al. distance.
In Chinese, Chinese: 天社 (Chinese: Tiān Shè), meaning Celestial Earth God's Temple, refers to an asterism consisting of Kappa Velorum, Gamma2 Velorum, b Velorum and Delta Velorum.[4] Consequently, Kappa Velorum itself is known as Chinese: 天社五 (Chinese: Tiān Shè wǔ), "the Fifth Star of Celestial Earth God's Temple".[5]