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.

  1. ^ a b Cite error: The named reference hipparcos was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference gcvs was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference gaia was invoked but never defined (see the help page).
  4. ^ a b c d Cite error: The named reference gallenne was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference groenewegen was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference caputo was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference romaniello was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference marsakov was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Laney was invoked but never defined (see the help page).
  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.