HD 95109

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
Evolutionary stage Yellow supergiant
Spectral type F6-G7 Iab[2]
Variable type δ Cep[2]
Astrometry
Proper motion (μ) RA: −5.963 mas/yr[3]
Dec.: +2.397 mas/yr[3]
Parallax (π)0.553 ± 0.0226 mas[3]
Distance6,187±218 ly
(1898±67 pc)[4]
Absolute magnitude (MV)−5.27[5]
Details
Mass7.5 - 11.7[6] M☉
Radius187±5[4] R☉
Luminosity26,642±1,584[4] L☉
Surface gravity (log g)1.2[7] cgs
Temperature5,397[4] – 5,980[7] K
Metallicity+0.01[8]
Age29[8] Myr
Other designations
U Car, CD−59°3448, HD 95109, HR 4276, HIP 52589
Database references
SIMBADdata

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)[9]

U Car is a δ Cepheid variable with a period of 38.7681 days. Isaac Roberts discovered that the star's brightness varies in 1891,[10] and 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.[11] 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.[12] The temperature variation causes the spectral type to vary between F6 and G7.

References

  1. ^ a b 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 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.
  4. ^ a b c d Gallenne, A.; Mérand, A.; Kervella, P.; Pietrzyński, G.; Gieren, W.; Hocdé, V.; Breuval, L.; Nardetto, N.; Lagadec, E. (May 25, 2021). "Extended envelopes around Galactic Cepheids. V. Multi-wavelength and time-dependent analysis of IR excess". Astronomy & Astrophysics. 651: A113. arXiv:2105.12197. Bibcode:2021A&A...651A.113G. doi:10.1051/0004-6361/202140350. ISSN 0004-6361.
  5. ^ 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.
  6. ^ 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.
  7. ^ 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.
  8. ^ 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.
  9. ^ 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.
  10. ^ Cannon, Annie J. (1907). "Second catalogue of variable stars". Annals of Harvard College Observatory. 55: 1–94. Bibcode:1907AnHar..55....1C. Retrieved 8 January 2025.
  11. ^ 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.
  12. ^ 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.