Alniyat

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Double star
σ Scorpii
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
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
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
Bayer name σ Scorpii
Flamsteed name 20 Scorpii
Cordoba Survey CD −25 ° 11485
Bright Star Catalog HR 6084 [1]
Henry Draper Catalog HD 147165 [2]
Hipparcos catalog HIP 80112 [3]
SAO catalog SAO 184336 [4]
Tycho catalog TYC 6798-540-1 [5]
2MASS catalog 2MASS J16211131-2535342 [6]
Other names Al Niyat, FK5 607

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.

Sigma Scorpii is in the center of the red cloud in the lower right

Web links

Individual evidence

  1. ↑ a b c d e f g h sig Sco. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed December 8, 2018 .
  2. ↑ a b c sig Sco. In: VSX. AAVSO, accessed December 8, 2018 .