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6 Geminorum

Location of 6 Geminorum (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Gemini
Right ascension	06 12 19.09884
Declination	+22° 54′ 30.6531″
Apparent magnitude (V)	5.74 – 8.10
Characteristics
Spectral type	M1-2 Ia-Iab
U−B color index	+1.93
B−V color index	+1.63
Variable type	LC
Astrometry
Radial velocity (Rv)	+27.16±0.42 km/s
Proper motion (μ)	RA: +0.144 mas/yr Dec.: −2.085 mas/yr
Parallax (π)	0.5642 ± 0.0957 mas
Distance	approx. 5,800 ly (approx. 1,800 pc)
Absolute magnitude (MV)	−6.32
Details
Mass	~20 M☉
Radius	821+60 −27 R☉
Luminosity	86,000 L☉
Surface gravity (log g)	0.0 cgs
Temperature	3,789 K
Other designations
6 Gem, BU Gem, BD+22°1220, GC 7896, HD 42543, HIP 29450, HR 2197, SAO 78098, TYC 1877-1719-1, 2MASS J06121911+2254305
Database references
SIMBAD	data

6 Geminorum is a variable star in the zodiac constellation of Gemini, located roughly 5,800 light years away from the Sun. It has the variable star designation BU Geminorum; 6 Geminorum is the Flamsteed designation. At its brightest this reddish hued star is barely visible to the naked eye but is readily visible with binoculars, found southeast of M 35, just to the south of WY Geminorum. It is moving further from the Earth with a heliocentric radial velocity of +27 km/s. The star is a member of the Gemini OB1 association.

This is an evolved red supergiant with a stellar classification of M1-2 Ia-Iab. It is a semiregular variable star, ranging from visual magnitude +5.7 down to +7.5 over a period of 325 days. It has been given the sub-classification of Lc, which means "Irregular variable supergiants of late spectral types having amplitudes of about 1 mag. in V.O". The star has expanded to 821 times the Sun's radius and is radiating 86,000 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 3,789 K.

• A light curve for BU Geminorum, plotted from TESS data
• Messier 35, with 6 Gem visible right at the bottom edge of the image

References

1. ^ 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.
2. ^ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
3. ^ Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373.
4. ^ Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
5. ^ Famaey, B.; et al. (January 2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters". Astronomy and Astrophysics. 430 (1): 165–186. arXiv:astro-ph/0409579. Bibcode:2005A&A...430..165F. doi:10.1051/0004-6361:20041272. S2CID 17804304.
6. ^ Levesque, Emily M. (2005). "The Effective Temperature Scale of Galactic Red Supergiants: Cool, but Not As Cool As We Thought". The Astrophysical Journal. 628 (2): 973–985. arXiv:astro-ph/0504337. Bibcode:2005ApJ...628..973L. doi:10.1086/430901. S2CID 15109583.
7. "6 GEM". 2012. Retrieved 15 December 2016.
8. ^ Norris, Ryan P. (2019). Seeing Stars Like Never Before: A Long-term Interferometric Imaging Survey of Red Supergiants (PDF) (PhD). Georgia State University.
9. ^ Mauron, N; Josselin, E (2011). "The mass-loss rates of red supergiants and the de Jager prescription". Astronomy and Astrophysics. 526: A156. arXiv:1010.5369. Bibcode:2011A&A...526A.156M. doi:10.1051/0004-6361/201013993. S2CID 119276502.
10. ^ Mármol-Queraltó, E; Cardiel, N; Cenarro, A. J; Vazdekis, A; Gorgas, J; Pedraz, S; Peletier, R. F; Sánchez-Blázquez, P (2008). "A new stellar library in the region of the CO index at 2.3 μm. New index definition and empirical fitting functions". Astronomy and Astrophysics. 489 (2): 885–909. arXiv:0806.0581. Bibcode:2008A&A...489..885M. doi:10.1051/0004-6361:200810044. S2CID 15411613.
11. "6 Gem". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-04-24.
12. Laur, Jaan; et al. (February 2017). "Variability survey of brightest stars in selected OB associations". Astronomy & Astrophysics. 598: 27. arXiv:1611.02452. Bibcode:2017A&A...598A.108L. doi:10.1051/0004-6361/201629395. S2CID 119076598. A108.
13. "Variable Star Type Designations in VSX]". Retrieved 2016-11-06.
14. "ASAS All Star Catalogue". The All Sky Automated Survey. Retrieved 8 December 2021.

v t e Constellation of Gemini
List of stars in Gemini Gemini in Chinese astronomy
Stars	Bayer α (Castor) β (Pollux) γ (Alhena) δ (Wasat) ε (Mebsuta) ζ (Mekbuda) η (Propus) θ ι κ λ μ (Tejat) ν ξ (Alzirr) ο (Jishui) π ρ σ τ υ φ χ ω Flamsteed 1 3 6 25 30 37 38 (e) 57 (A) 64 (b) 65 (b) 74 (f) 81 (g) Variable R U TV BG DM DN OU WY V429 HR 2877 HD 44780 50554 63433 260655 Other 2MASS 0727+1710 CXOU J061705.3+222127 Geminga Gliese 251 HAT-P-20 HAT-P-24 HAT-P-33 LB-1 PSR J0659+1414 WD J0651+2844 WISEP J060738.65+242953.4
Exoplanets HAT-P-24b HAT-P-50b HD 50554 b HD 59686 Ab Pollux b τ Geminorum b
Star clusters	NGC 2129 2158 2266 2277 2355 2420 Other Koposov 2 Messier 35
Nebulae IC 443 IC 444 Medusa Nebula NGC 2371-2 NGC 2392
Galaxies	NGC 2291 2294 2357 Other 2MASX J07322028+3138009 IC 485 PKS 0735+178
Astronomical events GRB 070125
Category

• M-type supergiants
• Slow irregular variables
• Gemini (constellation)
• 2MASS objects
• Durchmusterung objects
• Flamsteed objects
• Henry Draper Catalogue objects
• Hipparcos objects
• Bright Star Catalogue objects
• IRAS catalogue objects
• Objects with variable star designations