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] |
Distance | 6,187±218 ly (1898±67 pc) [4] |
Absolute magnitude (MV) | −5.27 [5] |
Details | |
Mass | 7.5 - 11.7 [6] M☉ |
Radius | 187±5 [4] R☉ |
Luminosity | 26,642±1,584 [4] L☉ |
Surface gravity (log g) | 1.2 [7] cgs |
Temperature | 5,397 [4] –5,980 [7] K |
Metallicity | +0.01 [8] |
Age | 29 [8] 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.
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.