HD 74180
Supergiant star in the constellation Vela
From Wikipedia, the free encyclopedia
HD 74180 (b Velorum) is a single[12] 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.
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Vela[1] |
| Right ascension | 08h 40m 37.57121s[2] |
| Declination | −46° 38′ 55.4644″[2] |
| Apparent magnitude (V) | 3.81[3] |
| Characteristics | |
| Evolutionary stage | Yellow supergiant or yellow hypergiant |
| Spectral type | F0Ia[4] or F0Ia+[5] |
| U−B color index | +0.34[3] |
| B−V color index | +0.67[6] |
| Variable type | suspected α Cyg[5] |
| Astrometry | |
| Radial velocity (Rv) | −25.3[7] km/s |
| Proper motion (μ) | RA: −6.124[2] mas/yr Dec.: +4.473[2] mas/yr |
| Parallax (π) | 0.431±0.101 mas[2] |
| Distance | 5,400+110 −140 ly (1,657+33 −44 pc)[8] |
| Absolute magnitude (MV) | −6.50[9] |
| Details | |
| Mass | 21.4±2.3[10] M☉ |
| Radius | 325±28[8] R☉ |
| Luminosity | 316,000+73,000 −65,000[8] L☉ |
| Surface gravity (log g) | 1.38[9] cgs |
| Temperature | 7,839[11] K |
| Metallicity [Fe/H] | +0.56[11] dex |
| Rotational velocity (v sin i) | 21.7±6[6] km/s |
| Age | 7.4±0.8[10] Myr |
| Other designations | |
| b Velorum, HR 3445, HD 74180, CD−46°4438, FK5 1226, HIP 42570, SAO 220265 | |
| Database references | |
| SIMBAD | data |
Properties
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.[5] It lies less than a degree from the small open cluster NGC 2645, but is not a member.[9]
Several studies have considered b Velorum to be a highly luminous supergiant or hypergiant with an early F spectral type, for example F2 Ia+,[5] F0 Ia,[4] and F4 I.[13] There were corresponding luminosity estimates of several hundred thousand L☉. Aidelman et al. (2015) used the Barbier-Chalonge-Divan (BCD) system to derive a luminosity of 34,000 L☉ and a cooler less luminous F8 Ib spectral type.[9] Kasikov et al. (2026) arrived with a luminosity of 316,000 L☉ based on an stellar radius of 325±28 R☉ and an effective temperature of 7,540 K from the average of earlier spectroscopic measurements.[8]
Parallax measurements by the Hipparcos and Gaia spacecrafts imply distances of 1490±360 pc (4,860 ly)[14] and 2,530+600
−397 pc (8,250 ly), respectively.[15] Aidelman et al. (2015) give a distance of 990 pc (3,200 ly).[9] Kasikov et al. (2026) estimated the distance using stars with similar proper motion and reliable Gaia parallaxes, giving a value of 1,657 parsecs (5,400 ly). This is consistent with the distance to NGC 2645, despite the star being not a member.[8]
In chinese astronomy
In Chinese, 天社 (Tiān Shè), meaning Celestial Earth God's Temple, refers to an asterism consisting of Kappa Velorum, Gamma2 Velorum, b Velorum and Delta Velorum.[16] Consequently, Kappa Velorum itself is known as 天社五 (Tiān Shè wǔ), "the Fifth Star of Celestial Earth God's Temple".[17]