HD 74180

This article is about b Velorum. For B Velorum, see HD 70930.

b Velorum

Location of b Vel (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Vela
Right ascension	08^h 40^m 37.57017^s[1]
Declination	−46° 38′ 55.4770″[1]
Apparent magnitude (V)	3.81[2]
Characteristics
Evolutionary stage	Yellow supergiant or yellow hypergiant
Spectral type	F8 Ib,[3] F0Ia^+[4] or F0Ia[5]
U−B color index	+0.34[2]
B−V color index	+0.67[6]
Variable type	suspected α Cyg[4]
Astrometry
Radial velocity (Rv)	−25.3[7] km/s
Proper motion (μ)	RA: −6.124[8] mas/yr Dec.: 4.473[8] mas/yr
Parallax (π)	0.431 ± 0.101 mas[9]
Distance	3,230 – 8,250[a] ly (990[3][b] – 2,532[9][c] pc)
Absolute magnitude (MV)	−6.50[3]
Details
Mass	12.63[3]–21.4±2.3[10] M☉
Radius	186[3][d] R☉
Luminosity	34,040[3][e] L☉
Surface gravity (log g)	1.38[3] cgs
Temperature	5,750[3] – 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][f] Myr
Other designations
b Velorum, HR 3445, HD 74180, CD−46°4438, FK5 1226, HIP 42570, SAO 220265
Database references
SIMBAD	data

HD 74180 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. Estimates of its distance to Earth vary between 3,200 and 8,300 light-years.

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.[3]

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,[5] and F4 I.[13] 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.[3]

Distance and size

Multiple papers give different distances for b Velorum. Bailer-Jones et al. (2021) give a distance of about 2,530 pc (8,300 ly).[9] The Hipparcos spacecraft give a parallax of 0.67±0.16 mas, translating into a distance of 1,492.5 pc (4,868 ly).[1] Aidelman et al. (2015) give a distance of 990 pc (3,200 ly).[3] At the Hipparcos distance, b Velorum has its apparent brightness diminished by 1.11 magnitudes due to interstellar extinction.[11]

b Velorum has an angular diameter estimated at 1.824 mas.[14] The physical size depends on the star's distance, and could be 190 R_☉ assuming the distance of Aidelman et al., 290 R_☉ assuming the Hipparcos distance, or even 500 R_☉ assuming the Bailer-Jones et al. distance.[15]

In chinese astronomy

In Chinese, 天社 (Tiān Shè), meaning Celestial Earth God's Temple, refers to an asterism consisting of Kappa Velorum, Gamma^2 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]

Notes

1. Margin of error of ^+1960
   ₋₁₂₉₀ for the second value
2. This distance applies is b Velorum has spectral type F8Ib.
3. Margin of error of ^+600
   ₋₃₉₇ for the second value
4. Applying the Stefan–Boltzmann law with a nominal solar effective temperature of 5,772 K:

   ${\displaystyle {\sqrt {(5772/5750)^{4}*34,040}}=185.91\ R\odot }$

5. From L = 10^(0.4*(4.74−(Mbol)), where L is the luminosity and M_bol the bolometric magnitude
6. Assuming 21.4 M_☉ as the mass

References

1. 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.
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.
3. 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.
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. 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.
6. 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. 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.
9. 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.
10. 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. 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. Cruzalèbes, P.; Petrov, R. G.; Robbe-Dubois, S.; Varga, J.; Burtscher, L.; Allouche, F.; Berio, P.; Hofmann, K. -H.; Hron, J.; Jaffe, W.; Lagarde, S.; Lopez, B.; Matter, A.; Meilland, A.; Meisenheimer, K. (2019-12-01). "A catalogue of stellar diameters and fluxes for mid-infrared interferometry". Monthly Notices of the Royal Astronomical Society. 490 (3): 3158–3176. arXiv:1910.00542. Bibcode:2019MNRAS.490.3158C. doi:10.1093/mnras/stz2803. ISSN 0035-8711.
15. Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R_*) is given by:

    ${\displaystyle {\begin{aligned}2\cdot R_{*}&={\frac {(10^{-3}\cdot 990\cdot 1.824)\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 388\cdot R_{\bigodot }\end{aligned}}}$
    ${\displaystyle {\begin{aligned}2\cdot R_{*}&={\frac {(10^{-3}\cdot 1493\cdot 1.824)\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 586\cdot R_{\bigodot }\end{aligned}}}$
    ${\displaystyle {\begin{aligned}2\cdot R_{*}&={\frac {(10^{-3}\cdot 2530\cdot 1.824)\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 993\cdot R_{\bigodot }\end{aligned}}}$

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.