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UU Aurigae
	Location of UU Aurgae (circled)
Observation data; Epoch J2000 Equinox J2000
Constellation	Auriga
Right ascension	06h 36m 32.83710s
Declination	+38° 26′ 43.8190″
Apparent magnitude (V)	4.9–7.0
Characteristics
Spectral type	C5,3-C7,4(N3)
B−V color index	2.61
R−I color index	1.43
Variable type	SRb
Astrometry
Radial velocity (Rv)	13.40 km/s
Proper motion (μ)	RA: 0.500 mas/yr ; Dec.: −19.758 mas/yr
Parallax (π)	2.0387 ± 0.1661 mas
Distance	341 pc
Absolute magnitude (MV)	−3.65
Details
Radius	370 R☉
Luminosity	16,443 L☉
Temperature	2,760 K
Other designations
	GC 8581, SAO 59280, BD+38° 1539, HD 46687, HIP 31579, HR 2405
Database references
SIMBAD	data

UU Aurigae is a carbon star in the constellation Auriga. It is approximately 341 parsecs (1,110 light-years) from Earth. It is a variable star that is occasionally bright enough to be seen by the naked eye under excellent observing conditions.

Description

John Birmingham observed the star from 1871 to 1875, and detected its variability. It was confirmed as a variable star by Thomas William Backhouse in 1905, based on observations from 1894 to 1904. It was given its variable star designation in 1912.^[9]^[10]

UU Aurigae is a carbon-rich asymptotic giant branch star. The spectral type listed in the General Catalogue of Variable Stars (GCVS) is C5,3-C7,4(N3). The N3 refers back to an older type of classification where carbon stars were given spectral types of N or R, although the numeric index was correlated more with the strength of the carbon chemistry rather than temperature. The C5 to C7 indicates various classifications using the newer Morgan-Keenan system where the numeric index corresponds better to the temperature of the star. C5 to C7 types are approximately equivalent to early-M stars. The second numeric index, 3 or 4 for UU Aurigae indicates the strength of the Swan bands in the spectrum, on a scale of 1 to 5.^[11] Using the more modern revised Morgan-Keenan scheme, a spectral type of C-N5- C2 6- has been published, with the C-N5 indicating an N-type carbon star with a temperature index of 5-, and a Swan band strength of 6- on a scale of 1 to 8.^[12]

A 28 year long visual band light curve for UU Aurigae, adapted from Howarth (2001)^[13]

UU Aurigae is classified as a semiregular variable of type SRb, indicating it is a giant star with poorly defined variations. Its brightness varies from magnitude +4.9 to +7.0 in visual apparent magnitude.^[2] The period is given in the GCVS as 441 days, but there is also a strong variation with a period of 235 days.^[14] Using British Astronomical Association observations from 1971 to 1998, the periods are calculated as 439.4 and 233.1 days.^[13]

The angular diameter of UU Aurigae has been measured at 12.07 ± 0.22 mas using very-long-baseline interferometry (VLBI).^[15] Around the star is a shell of dust made up largely of amorphous carbon and silicon carbide (SiC), with the SiC appearing at three times the star's radius and the amorphous carbon at nine times its radius. Further out is a carbon-rich shell at 300 stellar radii and two oxygen-rich shells even further away.^[16] UU Aurigae also has a bow shock 0.14 parsec wide, created by its motion through the interstellar medium.^[4]

References

^ ^a ^b ^c ^d ^e Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
^ ^a ^b ^c ^d 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.
^ Gontcharov, G. A (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
^ ^a ^b Cox, N. L. J; Kerschbaum, F; Van Marle, A.-J; Decin, L; Ladjal, D; Mayer, A; Groenewegen, M. A. T; Van Eck, S; Royer, P; Ottensamer, R; Ueta, T; Jorissen, A; Mecina, M; Meliani, Z; Luntzer, A; Blommaert, J. A. D. L; Posch, Th; Vandenbussche, B; Waelkens, C (2012). "A far-infrared survey of bow shocks and detached shells around AGB stars and red supergiants". Astronomy & Astrophysics. 537: A35. arXiv:1110.5486. Bibcode:2012A&A...537A..35C. doi:10.1051/0004-6361/201117910. S2CID 56041336.
^ Alksnis, A; Balklavs, A; Dzervitis, U; Eglitis, I (1998). "Absolute magnitudes of carbon stars from HIPPARCOS parallaxes". Astronomy and Astrophysics. 338: 209. Bibcode:1998A&A...338..209A.
^ Luttermoser, Donald G.; Brown, Alexander (1992). "A VLA 3.6 centimeter survey of N-type carbon stars". Astrophysical Journal. 384: 634. Bibcode:1992ApJ...384..634L. doi:10.1086/170905.
^ ^a ^b Bergeat, J; Knapik, A; Rutily, B (2002). "Carbon-rich giants in the HR diagram and their luminosity function". Astronomy and Astrophysics. 390 (3): 967. Bibcode:2002A&A...390..967B. doi:10.1051/0004-6361:20020525.
^ "V* UU Aur". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 6 February 2018.
^ Dunér; Hartwig; Müller (June 1912). "Benennung von neu entdeckten veränderlichen Sternen". Astronomische Nachrichten. 191 (19): 341. Bibcode:1912AN....191..341.. doi:10.1002/asna.19121911902. Retrieved 30 November 2024.
^ Backhouse, Thomas William (1905). Observations of variable stars. Sunderland: Hills & co. p. 48. Bibcode:1905ovs..book.....B. Retrieved 30 November 2024.
^ Keenan, P. C. (1993). "Revised MK Spectral Classification of the Red Carbon Stars". Publications of the Astronomical Society of the Pacific. 105: 905. Bibcode:1993PASP..105..905K. doi:10.1086/133252.
^ Barnbaum, Cecilia; Stone, Remington P. S; Keenan, Philip C (1996). "A Moderate-Resolution Spectral Atlas of Carbon Stars: R, J, N, CH, and Barium Stars". Astrophysical Journal Supplement. 105: 419. Bibcode:1996ApJS..105..419B. doi:10.1086/192323.
^ ^a ^b Howarth, J. J. (June 2001). "The semiregular variable UU Aurigae - analysis in adversity?". Journal of the British Astronomical Association. 111: 150–152. Bibcode:2001JBAA..111..150H. Retrieved 1 November 2021.
^ Kiss, L. L; Szatmáry, K; Cadmus, R. R; Mattei, J. A (1999). "Multiperiodicity in semiregular variables. I. General properties". Astronomy and Astrophysics. 346: 542. arXiv:astro-ph/9904128. Bibcode:1999A&A...346..542K.
^ Quirrenbach, A; Mozurkewich, D; Hummel, C. A; Buscher, D. F; Armstrong, J. T (1994). "Angular diameters of the carbon stars UU Aurigae, Y Canum Venaticorum, and TX PISCIUM from optical long-baseline interferometry". Astronomy and Astrophysics. 285: 541. Bibcode:1994A&A...285..541Q.
^ Bagnulo, S; Skinner, C. J; Doyle, J. G; Camphens, M (1997). "Carbon stars with detached dust shells: The circumstellar envelope of UU Aurigae". Astronomy and Astrophysics. 321: 605. Bibcode:1997A&A...321..605B.