b Velorum
Location of b Vel (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Vela
Right ascension 08h 40m 37.57017s[1]
Declination −46° 38′ 55.4770″[1]
Apparent magnitude (V) 3.81[2]
Characteristics
Spectral type F0Ia[3]
U−B color index +0.34[2]
B−V color index +0.71[2]
Variable type suspected α Cyg[4]
Astrometry
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 mas[1]
Distance990[6] pc
Absolute magnitude (MV)−6.50[6]
Details
Mass12.63[6] M☉
Radius196[6][lower-alpha 1] R☉
Luminosity38,000[6] L☉
Surface gravity (log g)1.38[6] cgs
Temperature5,750[6] K
Metallicity [Fe/H]0.56[7] dex
Rotational velocity (v sin i)21.7[8] km/s
Other designations
b Velorum, HR 3445, HD 74180, CD−46°4438, FK5 1226, HIP 42570, SAO 220265
Database references
SIMBADdata

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.[9]

A light curve for HD 74180, adapted from van Leeuwen et al. (1998)[4]

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] It lies less than a degree from the small open cluster NGC 2645, but is not a member.[6]

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,[10] and F4 I.[11] 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.[6]

Nomenclature

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.[12] Consequently, Kappa Velorum itself is known as 天社五 (Tiān Shè wǔ), "the Fifth Star of Celestial Earth God's Temple".[13]

References

  1. 1 2 3 4 5 van Leeuwen, Floor (13 August 2007). "Validation of the new Hipparcos reduction". Astronomy & Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. eISSN 1432-0746. ISSN 0004-6361.
  2. 1 2 3 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. ↑ Houk, Nancy (1978). "Michigan catalogue of two-dimensional spectral types for the HD stars". Ann Arbor: Dept. Of Astronomy, University of Michigan. 2. Bibcode:1978mcts.book.....H.
  4. 1 2 3 4 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.
  5. ↑ Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
  6. 1 2 3 4 5 6 7 8 9 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.
  7. ↑ 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.
  8. ↑ 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
  9. ↑ Mason, B. D.; et al. (2014). "The Washington Visual Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
  10. ↑ 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.
  11. ↑ 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.
  12. ↑ (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.
  13. ↑ (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.
  1. ↑ Radius calculated with temperature and luminosity
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