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 [1]
Right ascension	08h 40m 37.57017s [2]
Declination	−46° 38′ 55.4770″ [2]
Apparent magnitude  (V)	3.81 [3]
Characteristics
Evolutionary stage	Yellow supergiant or yellow hypergiant
Spectral type	F8 Ib, [4] F0Ia+ [5] or F0Ia [6]
U−B color index	+0.34 [3]
B−V color index	+0.67 [7]
Variable type	suspected α Cyg [5]
Astrometry
Radial velocity (Rv)	−25.3 [8] km/s
Proper motion (μ)	RA: −6.124 [9] mas/yr Dec.: +4.473 [9] mas/yr
Parallax (π)	0.431±0.101  mas [10]
Distance	3,230 –8,250 [a]   ly (990 [4] [b]  –2,532 [10] [c]   pc)
Absolute magnitude  (MV)	−6.50 [4]
Details
Mass	12.63 [4] –21.4±2.3 [11]   M☉
Radius	186 [4] [d]   R☉
Luminosity	34,040 [4] [e]   L☉
Surface gravity (log g)	1.38 [4]   cgs
Temperature	5,750 [4]  –7,839 [12]   K
Metallicity [Fe/H]	0.56 [12]   dex
Rotational velocity (v sin i)	21.7±6 [7]  km/s
Age	7.4±0.8 [11] [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 ^[13] 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.

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. ^[5] It lies less than a degree from the small open cluster NGC 2645, but is not a member. ^[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⁺, ^[5] F0 Ia, ^[6] and F4 I. ^[14] 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. ^[4]

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 ). ^[10] The Hipparcos spacecraft give a parallax of 0.67±0.16  mas , translating into a distance of 1,492.5 pc (4,868 ly). ^[2] Aidelman et al. (2015) give a distance of 990 pc (3,200 ly). ^[4] At the Hipparcos distance, b Velorum has its apparent brightness diminished by 1.11  magnitudes due to interstellar extinction. ^[12]

b Velorum has an angular diameter estimated at 1.824  mas . ^[15] 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. ^[16]

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. ^[17] Consequently, Kappa Velorum itself is known as 天社五 (Tiān Shè wǔ), "the Fifth Star of Celestial Earth God's Temple". ^[18]

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−(M_bol))}, where L is the luminosity and M_bol the bolometric magnitude
6. Assuming 21.4 M_☉ as the mass

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. 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.
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.
4. 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 .
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. 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.
7. 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.
8. Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
9. 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.
10. 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.
11. 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.
12. 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.
13. 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.
14. 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.
15. 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.
16. 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:

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

17. (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.
18. (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.