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. 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.[10] 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.[11] 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. ^ 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.
  11. ^ 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.