HD 95109

HD 95109

Template:Location mark Location of U Carinae (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Carina
Right ascension	Template:RA
Declination	Template:DEC
Apparent magnitude (V)	5.72 - 6.90
Characteristics
Evolutionary stage	Yellow supergiant
Spectral type	F6-G7 Iab
Variable type	δ Cep
Astrometry
Proper motion (μ)	RA:  mas/yr Dec.: +2.397 mas/yr
Parallax (π)	0.553±0.0226 mas
Distance	ly ( pc)
Absolute magnitude (MV)	−5.27
Details
Mass	7.5 - 11.7 Template:Solar mass
Radius	Template:Solar radius
Luminosity	Template:Solar luminosity
Surface gravity (log g)	1.2 cgs
Temperature	5,397Template:Snd5,980 K
Metallicity	+0.01
Age	29 Myr
Metallicity [Fe/H]	{{{metal_fe2}}} dex
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.

File:UCarLightCurve.png

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

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, 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. There are still only a few Cepheids with longer periods, including RS Puppis, SV Vulpeculae, and the unusual S Vulpeculae.

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