HD 74180

b Velorum
Location of b Vel (circled)
Observation data
Epoch J2000      Equinox ICRS
Constellation Vela
Right ascension 08h 40m 37.57121s
Declination −46° 38′ 55.4644″
Apparent magnitude (V) 3.81
Characteristics
Evolutionary stage Yellow supergiant or yellow hypergiant
Spectral type F0Ia or F0Ia+
U−B color index +0.34
B−V color index +0.67
Variable type suspected α Cyg
Astrometry
Radial velocity (Rv)−25.3 km/s
Proper motion (μ) RA: −6.124 mas/yr
Dec.: +4.473 mas/yr
Parallax (π)0.431±0.101 mas
Distance5,400+110
−140 ly
(1,657+33
−44 pc)
Absolute magnitude (MV)−6.50
Details
Mass21.4±2.3 M☉
Radius325±28 R☉
Luminosity316,000+73,000
−65,000 L☉
Surface gravity (log g)1.38 cgs
Temperature7,839 K
Metallicity [Fe/H]+0.56 dex
Rotational velocity (v sin i)21.7±6 km/s
Age7.4±0.8 Myr
Other designations
b Velorum, HR 3445, HD 74180, CD−46°4438, FK5 1226, HIP 42570, SAO 220265
Database references
SIMBADdata

HD 74180 (b Velorum) 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.

Properties

A light curve for HD 74180, adapted from van Leeuwen et al. (1998)

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☉. 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. 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.

Parallax measurements by the Hipparcos and Gaia spacecraft imply distances of 1490±360 pc (4,860 ly) and 2,530+600
−397 pc (8,250 ly), respectively. Aidelman et al. (2015) give a distance of 990 pc (3,200 ly). 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.

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. Consequently, Kappa Velorum itself is known as 天社五 (Tiān Shè wǔ), "the Fifth Star of Celestial Earth God's Temple".

References

  1. ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.
  2. 1 2 3 4 5 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  3. 1 2 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  4. 1 2 Humphreys, R. M. (1978). "Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way". Astrophysical Journal. 38: 309. Bibcode:1978ApJS...38..309H. doi:10.1086/190559.
  5. 1 2 3 4 5 Van Leeuwen, F.; Van Genderen, A. M.; Zegelaar, I. (1998). "Hipparcos photometry of 24 variable massive stars (α Cygni variables)". Astronomy and Astrophysics Supplement Series. 128: 117–129. Bibcode:1998A&AS..128..117V. doi:10.1051/aas:1998129.
  6. 1 2 Ammler-von Eiff, Matthias; Reiners, Ansgar (June 2012), "New measurements of rotation and differential rotation in A-F stars: are there two populations of differentially rotating stars?", Astronomy & Astrophysics, 542: A116, arXiv:1204.2459, Bibcode:2012A&A...542A.116A, doi:10.1051/0004-6361/201118724, S2CID 53666672 b Velorum's database entry at VizieR.
  7. ↑ Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
  8. 1 2 3 4 5 Kasikov, A.; Mehner, A.; Kolka, I.; Aret, A. (2026-02-02). "Painting a Family Portrait of the Yellow Super- and Hypergiants in the Milky Way I. Constraining the Distances and Luminosities". Astronomy and Astrophysics. arXiv:2602.02449.
  9. 1 2 3 4 5 Aidelman, Y.; Cidale, L. S.; Zorec, J.; Panei, J. A. (2015). "Open clusters. II. Fundamental parameters of B stars in Collinder 223, Hogg 16, NGC 2645, NGC 3114, and NGC 6025". Astronomy & Astrophysics. 577: A45. Bibcode:2015A&A...577A..45A. doi:10.1051/0004-6361/201425085. hdl:11336/14076.
  10. 1 2 Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (2011-01-01). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410 (1): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x. ISSN 0035-8711. b Velorum's database entry at VizieR.
  11. 1 2 Luck, R. Earle (2014). "Parameters and Abundances in Luminous Stars". The Astronomical Journal. 147 (6): 137. Bibcode:2014AJ....147..137L. doi:10.1088/0004-6256/147/6/137. b Velorum's database entry at VizieR.
  12. ↑ Eggleton, P. P.; Tokovinin, A. A. (2008-09-01). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. ISSN 0035-8711. b Velorum's database entry at VizieR.
  13. ↑ Mersch, G.; Heck, A. (1980). "Prediction of spectral classification from photometric observations - Application of the UVBY beta photometry and the MK spectra classification. II - General case". Astronomy and Astrophysics. 85: 93. Bibcode:1980A&A....85...93M.
  14. ↑ van Leeuwen, F. (2007-11-01). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. ISSN 0004-6361. b Velorum's database entry at VizieR.
  15. ↑ Bailer-Jones, C. A. L.; Rybizki, J.; Fouesneau, M.; Demleitner, M.; Andrae, R. (2021-03-01). "Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3". The Astronomical Journal. 161 (3): 147. arXiv:2012.05220. Bibcode:2021AJ....161..147B. doi:10.3847/1538-3881/abd806. ISSN 0004-6256. Data about this star can be seen here.
  16. ↑ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  17. ↑ (in Chinese) 香港太空館 – 研究資源 – 亮星中英對照表 Archived 2008-10-25 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.