1 Centauri
{{Short description|Yellow-white-hued star in the constellation Centaurus}}
{{redirect-distinguish|i centauri|HD 102776{{!}}j centauri|HD 110073{{!}}l Centauri|Iota Centauri{{!}}ι Centauri}}
{{Starbox begin
| name = 1 Centauri
}}
{{Starbox observe
| epoch= J2000.0
| constell = Centaurus
| dec = {{DEC|−33|02|37.3997}}
}}
{{Starbox character
| variable =
}}
{{Starbox astrometry
| radial_v = {{Val|−21.5|0.6}}
| prop_mo_ra = {{val|−462.49|0.18}}
| prop_mo_dec = {{val|−146.49|0.16}}
| parallax = 51.54
| p_error = 0.19
}}
{{Starbox orbit
| period_unitless = {{Val|9.94480|0.00441|fmt=none|u=d}}
| eccentricity = {{Val|0.247|0.105}}
| periastron = {{nowrap|2,422,737.382 ± 3.35 JD}}
| periarg = {{Val|137.7|25.4}}
| k1 = {{Val|6.00|0.75}}
}}
{{Starbox detail
| radius =
| luminosity_bolometric = 5.857
| temperature = {{Val|6898|235|fmt=commas}}
| rotation = {{Val|2.42|0.22}}
}}
{{Starbox catalog
| names = {{odlist | B=i Centauri | F=1 Centauri | CD=−32°9603 | FK5=506 | GJ=525.1 | HD=119756 | HIP=67153 | HR=5168 | SAO=204812 | GC=18593 }}{{cite simbad | title=1 Cen | access-date=2018-02-09 }}
}}
{{Starbox reference
| Simbad=1+Cen
}}
{{Starbox end}}
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 63.3 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.
References
{{reflist|refs=
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| publisher=Dept. of Astronomy, University of Michigan
| date=1979 | bibcode=1982mcts.book.....H }}
| title=Radial velocity determinations : including a spectroscopic determination of the constant of aberration, the orbits of 13 spectroscopic binary stars, and the radial velocities of 434 stars
| last1=Spencer Jones | first1=Harold
| journal=Annals of the Cape Observatory
| volume=10 | year=1928 | pages=246
| bibcode=1928AnCap..10....8S | postscript=. }}
| title=Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc--The Southern Sample
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| journal=International Astronomical Union, Colloquium on Spectral Classification of the Future, Vatican City, July 11–15, 1978. Ricerche Astronomiche (IAU Colloquium 47)
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| doi=10.1051/0004-6361:20078357 | s2cid=18759600 }} [http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/311/hip2&recno=66925 Vizier catalog entry ]
}}
{{Stars of Centaurus}}
{{DEFAULTSORT:1 Centauri}}
Category:F-type main-sequence stars