1 Centauri
1 Centauri, or i Centauri, is a yellow-white hued binary star system in the southern constellation Centaurus. It can be seen with the naked eye, having an apparent visual magnitude of +4.23. Based upon an annual parallax shift of 51.54 mas as seen from Earth's orbit, it is located 51.5 light years from the Sun. The system is moving closer to the Sun with a radial velocity of −21.5 km/s.

Spectrographic images taken at the Cape Observatory between 1921 and 1923 showed this star has a variable radial velocity, which indicated this is a single-lined spectroscopic binary star system. The pair have an orbital period of 9.94 days and an eccentricity of about 0.2.

The primary component has received a number of different stellar classifications. For example, Jaschek et al. (1964) lists F0V, F2III, F4III, and F4IV, thus ranging in evolutionary state from an ordinary F-type main-sequence star to a giant star. More recently, Houk (1982) listed a class of F3 V, matching an ordinary main-sequence star that is generating energy through hydrogen fusion at its core. The NStars project gives it a classification of F2 V.
Q50053
binary star
Concept
Q8928
constellation
Concept
Q8844
Centaurus
CEL
Q124313
apparent visual magnitude
Concept
Q906561
parallax shift
Concept
Q12097402
mas
Concept
Q531
light year
Concept
Q240105
radial velocity
Concept
Q227807
Cape Observatory
LOC
Q240105
radial velocity
Concept
Q50053
spectroscopic binary
Concept
Q37640
orbital period
Concept
Q208474
eccentricity
Concept
Q25377588
stellar classification
Concept
Q6472
evolutionary
Concept
Q1353952
F-type main-sequence star
Concept
Q5875
giant star
Concept
Q13082
hydrogen fusion
Concept
Q60790215
core
Concept
Q4595939
1 Centauri
CEL
1921-01-01T00:00:00Z^^http://www.w3.org/2001/XMLSchema#dateTime
1921
DATE
1923-01-01T00:00:00Z^^http://www.w3.org/2001/XMLSchema#dateTime
1923
DATE
+1^^http://www.w3.org/2001/XMLSchema#decimal
1
NUMBER
++4.23^^http://www.w3.org/2001/XMLSchema#decimal
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NUMBER
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51.54
NUMBER
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NUMBER
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9.94
NUMBER
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0.2
NUMBER
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1964
NUMBER
0^^http://www.w3.org/2001/XMLSchema#decimal
0
NUMBER
+2^^http://www.w3.org/2001/XMLSchema#decimal
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NUMBER
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4
NUMBER
+4^^http://www.w3.org/2001/XMLSchema#decimal
4
NUMBER
+1982^^http://www.w3.org/2001/XMLSchema#decimal
1982
NUMBER
+3^^http://www.w3.org/2001/XMLSchema#decimal
3
NUMBER
+2^^http://www.w3.org/2001/XMLSchema#decimal
2
NUMBER
constellation
instance of