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This article is about the variable star: U carinae. For u Carinae, see HD 94510.
HD 95109
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]
Characteristics
Spectral type F6-G7 Iab [2]
Variable type δ Cep [2]
Astrometry
Proper motion (μ) RA: −5.73 [1]  mas/ yr
Dec.: 1.89 [1]  mas/ yr
Parallax (π)0.21 ± 0.56  mas [1]
Distance1,401 [3]  pc
Absolute magnitude (MV)−5.27 [3]
Details
Mass7.5 - 11.7 [4]  M☉
Radius140.7 [3]  R☉
Luminosity15,000 [5]  L☉
Surface gravity (log g)1.2 [6]  cgs
Temperature5,980 [6]  K
Metallicity+0.01 [7]
Age29 [7]  Myr
Other designations
U Car, CD−59°3448, HD 95109, HR 4276, HIP 52589
Database references
SIMBAD data

HD 95109 (U Carinae) is a Classical Cepheid variable, a type of variable star, in the constellation Carina. Its apparent magnitude is 6.86.

A near-infrared ( J band) light curve for U Carinae, adpated from Laney and Stobie (1992) [8]

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. [9] 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. [10] The temperature variation causes the spectral type to vary between F6 and G7.

References

  1. ^ a b c d e Van Leeuwen, F. (2007). "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. S2CID  18759600.
  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. arXiv: 1212.5478. Bibcode: 2013A&A...550A..70G. doi: 10.1051/0004-6361/201220446. S2CID  118665355.
  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): 1021–1033. arXiv: astro-ph/0505149. Bibcode: 2005ApJ...629.1021C. doi: 10.1086/431641. S2CID  17359646.
  5. ^ Tsvetkov, Ts. G. (1985). "Population I pulsating stars. I - Period-luminosity (-colour) relations". Astrophysics and Space Science. 117 (2): 227. Bibcode: 1985Ap&SS.117..227T. doi: 10.1007/BF00650149. S2CID  119667397.
  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: 0807.1196. Bibcode: 2008A&A...488..731R. doi: 10.1051/0004-6361:20065661. S2CID  16955805.
  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. S2CID  119788977.
  8. ^ Laney, C. D.; Stobie, R. S. (April 1992). "JHKL Observations of Galactic Cepheids". Astronomy & Astrophysics Supplement Series. 93: 93–120. Bibcode: 1992A&AS...93...93L. Retrieved 20 November 2021.
  9. ^ 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.
  10. ^ 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.
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