Theta Carinae

θ Carinae

Location of θ Carinae (circled)
Observation data J2000.0
Constellation	Carina
Right ascension	10h 42m 57.40197s[1]
Declination	−64° 23′ 40.0208″[1]
Apparent magnitude (V)	2.76[2]
Characteristics
Evolutionary stage	Blue straggler[3][4]
Spectral type	B0.5 Vp[5]
U−B color index	−1.00[2]
B−V color index	−0.22[2]
Distance		460 ± 10 ly (140 ± 4 pc)
Absolute magnitude (MV)	−3.10[7]
Semi-amplitude (K1) (primary)		18.93±0.05 km/s
Details
θ Car A
Myr
SAO 251083.[12]
Database references
SIMBAD	data

θ Carinae,

The

Theta Carinae is a single-lined spectroscopic binary with a 2.2 day period; the shortest known orbital period among massive stars, suggesting earlier mass transfer between the two components, possibly explaining the spectral peculiarities.[4] In this spectroscopic system, the primary star is a blue straggler, which is an unusual type of star created by merging or the interaction between two or more stars. The source of the mass transfer is likely to be the less massive secondary companion, and what is now the primary star was probably originally the less massive component.^[4] The estimated age of the pair is 4 million years,^[8] and it appears much younger than the surrounding IC 2602 cluster.^[4]

The primary star is about 15 

In Chinese, 南船 (Nán Chuán), meaning Southern Boat, refers to an asterism consisting of θ Carinae, V337 Carinae, PP Carinae, β Carinae and ω Carinae.^[13] Consequently, θ Carinae itself is known as 南船三 (Nán Chuán sān, English: the Third Star of Southern Boat).^[14]

In most versions of its asterism, the neighbouring bright stars, thus plotted along the imaginary hull forming Carina are Omega Carinae which is approximately 120 light years closer and PP (also known as p) Carinae, of a similar distance to Theta.