Supergiant star in the constellation Vela
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! style="text-align: center; background-color: #FFFFC0;" colspan="2" | Observation dataEpoch J2000      Equinox J2000
! style="text-align:left" | Constellation
! style="text-align:left" | Right ascension
! style="text-align:left" | Declination
! style="text-align:left" | Apparent magnitude (V)
! style="background-color: #FFFFC0; text-align: center;" colspan="2"| Characteristics
! style="text-align:left" | Evolutionary stage
! style="text-align:left" | Spectral type
! style="text-align:left" | U−B 
! style="text-align:left" | B−V 
! style="text-align:left" | Variable type
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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, and F4 I. There were corresponding luminosity estimates of several hundred thousand L☉. A 2015 study used the Barbier-Chalonge-Divan (BCD) system to derive a luminosity of 34,000 L☉ and a cooler less luminous F8 Ib spectral type.
Distance and size.
Multiple papers give different distances for b Velorum. Bailer-Jones "et al." (2021) give a distance of about . The Hipparcos spacecraft give a parallax of , translating into a distance of . Aidelman "et al." (2015) give a distance of . 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 . The physical size depends on the star's distance, and could be R☉ assuming the distance of Aidelman "et al.", R☉ assuming the Hipparcos distance, or even R☉ assuming the Bailer-Jones "et al." distance.
In chinese astronomy.
In Chinese, (), meaning "Celestial Earth God's Temple", refers to an asterism consisting of Kappa Velorum, Gamma2 Velorum, b Velorum and Delta Velorum. Consequently, Kappa Velorum itself is known as (), "the Fifth Star of Celestial Earth God's Temple".
References.
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