Alniyat
Double star σ Scorpii |
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AladinLite | |||||||||||||||||||||
Observation dates equinox : J2000.0 , epoch : J2000.0 |
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Constellation | Scorpio | ||||||||||||||||||||
Right ascension | 16 h 21 m 11.32 s | ||||||||||||||||||||
declination | −25 ° 35 ′ 34.1 ″ | ||||||||||||||||||||
Apparent brightness | 2.89 (2.86 to 2.94) mag | ||||||||||||||||||||
Typing | |||||||||||||||||||||
B − V color index | +0.13 | ||||||||||||||||||||
U − B color index | −0.70 | ||||||||||||||||||||
R − I index | +0.11 | ||||||||||||||||||||
Spectral class | B2 III / O9.5 V | ||||||||||||||||||||
Variable star type | BCEP | ||||||||||||||||||||
Astrometry | |||||||||||||||||||||
Radial velocity | (−0.4 ± 0.9) km / s | ||||||||||||||||||||
parallax | (4.68 ± 0.60) mas | ||||||||||||||||||||
distance | 700 ly 210 pc |
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Proper movement | |||||||||||||||||||||
Rec. Share: | (−10.60 ± 0.78) mas / a | ||||||||||||||||||||
Dec. portion: | (−16.28 ± 0.43) mas / a | ||||||||||||||||||||
Physical Properties | |||||||||||||||||||||
Other names and catalog entries |
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Alniyat ( Arabic النياط, DMG an-niyāṭ ) is the main component of the Sigma Scorpii star system ( σ Sco for short ) in the constellation Scorpio , which is around 700 light years away . The apparent brightness fluctuates barely perceptibly between 2.86 and 2.94 mag. This name was officially confirmed by the IAU on February 1, 2017 . In historical Arabic astronomy, this name was also used for the star Tau Scorpii .
Alniyat is a classic representative of the β-Cephei variables and belongs to the spectral class B2 III. Its accompanying component is a main sequence star with the spectral class O9.5 V. Both stars orbit each other at a distance comparable to Venus - Sun every 33 days. Two other stars also belong to this system, which means that the system consists of 4 components.