HD 74180

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b Velorum
Vela constellation map.svg
Red circle.svg
Location of b Vel (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ara
Right ascension 08h 40m 37.57017s[1]
Declination −46° 38′ 55.4770″[1]
Apparent magnitude (V) 3.81[2]
Spectral type F8Ib[3]
U−B color index +0.34[2]
B−V color index +0.71[2]
Variable type suspected α Cyg[4]
Radial velocity (Rv) −25.3[5] km/s
Proper motion (μ) RA: −6.055[1] mas/yr
Dec.: 4.66[1] mas/yr
Parallax (π) 0.68 ± 0.16[1] mas
Distance 990[3] pc
Absolute magnitude (MV) −6.50[3]
Mass 12.63[3] M
Luminosity 38,000[3] L
Surface gravity (log g) 1.38[3] cgs
Temperature 5,750[3] K
Metallicity [Fe/H] 0.56[6] dex
Rotational velocity (v sin i) 21.7[7] km/s
Other designations
b Velorum, HR 6513, HD 74180, CD−46°4438, FK5 1226, HIP 42570, SAO 220265
Database references

HD 74180 is a binary star in the constellation Vela. It is approximately 3,200 light years from Earth. The primary component is a yellow-white F-type supergiant with a mean apparent magnitude of +3.81, with a 10th magnitude companion 37.5 arcseconds distant.

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.[4]

Several studies have considered b Velorum to be a highly luminous supergiant or hypergiant with an early F spectral type, for example F2 Ia+,[4] F0 Ia,[8] and F4 I.[9] 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 38,000 L and a cooler less luminous F8 Ib spectral type.[3]


  1. ^ a b c d e Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  2. ^ a b c 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. 
  3. ^ a b c d e f g h 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. 
  4. ^ a b c 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. Bibcode:1998A&AS..128..117V. doi:10.1051/aas:1998129. 
  5. ^ Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W. 
  6. ^ 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. 
  7. ^ Ammler-von Eiff, M.; Reiners, A. (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:1204.2459Freely accessible. Bibcode:2012A&A...542A.116A. doi:10.1051/0004-6361/201118724. 
  8. ^ 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. 
  9. ^ 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.