U Carinae

From Wikipedia, the free encyclopedia
Jump to: navigation, search
For u Carinae, see HD 94510.
U Carinae
Carina constellation map.svg
Red circle.svg

Location of U Carinae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Carina
Right ascension 10h 57m 48.18690s[1]
Declination −59° 43′ 55.8872″[1]
Apparent magnitude (V) 5.72 - 6.90[2]
Spectral type F6-G7 Iab[2]
Variable type δ Cep[2]
Proper motion (μ) RA: −5.73[1] mas/yr
Dec.: 1.89[1] mas/yr
Parallax (π) 0.21 ± 0.56[1] mas
Distance 1,401[3] pc
Absolute magnitude (MV) −5.27[3]
Mass 7.5 - 11.7[4] M
Radius 140.7[3] R
Luminosity 15,000[5] L
Surface gravity (log g) 1.2[6] cgs
Temperature 5,980[6] K
Metallicity +0.01[7]
Age 29[7] Myr
Other designations
U Car, CD−59°3448, HD 95109, HR 4276, HIP 52589
Database references

U Carinae (U Car) is a Classical Cepheid variable, a type of variable star, in the constellation Carina. Its apparent magnitude is 6.86.

U Car is a δ Cepheid variable with a period of 38.7681 days. It was one of the earliest Cepheids to be discovered. It has also one of the longest periods, and hence is one of the most luminous in the class.[8] There are still only a few Cepheids with longer periods, including RS Puppis, SV Vulpeculae, and the unusual S Vulpeculae.[2]

The brightness variation in U Car is caused by fundamental mode pulsations. The radius and temperature both vary, with the radius changing by 42 R during each cycle.[9] The temperature variation causes the spectral type to vary between F6 and G7.


  1. ^ a b c d e Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  2. ^ 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. 
  3. ^ a b c Groenewegen, M. A. T. (2013). "Baade-Wesselink distances to Galactic and Magellanic Cloud Cepheids and the effect of metallicity". Astronomy & Astrophysics. 550: A70. Bibcode:2013A&A...550A..70G. doi:10.1051/0004-6361/201220446. 
  4. ^ Caputo, F.; Bono, G.; Fiorentino, G.; Marconi, M.; Musella, I. (2005). "Pulsation and Evolutionary Masses of Classical Cepheids. I. Milky Way Variables". The Astrophysical Journal. 629 (2): 1021. Bibcode:2005ApJ...629.1021C. doi:10.1086/431641. 
  5. ^ Tsvetkov, Ts. G. (1985). "Population I pulsating stars. I - Period-luminosity (-colour) relations". Astrophysics and Space Science (ISSN 0004-640X). 117 (2): 227. Bibcode:1985Ap&SS.117..227T. doi:10.1007/BF00650149. 
  6. ^ a b Romaniello, M.; Primas, F.; Mottini, M.; Pedicelli, S.; Lemasle, B.; Bono, G.; François, P.; Groenewegen, M. A. T.; Laney, C. D. (2008). "The influence of chemical composition on the properties of Cepheid stars. II. The iron content". Astronomy and Astrophysics. 488 (2): 731. arXiv:0807.1196free to read. Bibcode:2008A&A...488..731R. doi:10.1051/0004-6361:20065661. 
  7. ^ a b Marsakov, V. A.; Koval', V. V.; Kovtyukh, V. V.; Mishenina, T. V. (2013). "Properties of the population of classical Cepheids in the Galaxy". Astronomy Letters. 39 (12): 851. Bibcode:2013AstL...39..851M. doi:10.1134/S1063773713120050. 
  8. ^ Shapley, H. (1918). "Studies based on the colors and magnitudes in stellar clusters. VIII. The luminosities and distances of 139 Cepheid variables". Astrophysical Journal. 48: 279. Bibcode:1918ApJ....48..279S. doi:10.1086/142435. 
  9. ^ Laney, C. D.; Stobie, R. S. (1995). "The radii of Galactic Cepheids". Monthly Notices of the Royal Astronomical Society. 274 (2): 337. Bibcode:1995MNRAS.274..337L. doi:10.1093/mnras/274.2.337.