"Al Niyat" redirects here. For the other star that traditionally bore this name, see Tau Scorpii.
Multiple star system in the constellation of Scorpius
Sigma Scorpii
Location of σ Scorpii (circled)
Observation data Epoch J2000.0 Equinox J2000.0
Constellation
Scorpius
Right ascension
16h 21m 11.31571s[1]
Declination
−25° 35′ 34.0515″[1]
Apparent magnitude (V)
+2.88[2]
Characteristics
Spectral type
B1 III[3] + B1 V[4]
U−B color index
−0.70[2]
B−V color index
+0.13[2]
Astrometry
Radial velocity (Rv)
−0.4[5] km/s
Proper motion (μ)
RA: −10.60[1] mas/yr Dec.: −16.28[1] mas/yr
Distance
568+75 −59 ly (174+23 −18[4] pc)
Absolute magnitude (MV)
−4.12±0.34 / −3.32±0.34[4]
Orbit[4]
Primary
σ Sco Aa1
Companion
σ Sco Aa2
Period (P)
33.010±0.002 days
Semi-major axis (a)
3.62±0.06 mas
Eccentricity (e)
0.3220±0.0012
Inclination (i)
158.2±2.3°
Longitude of the node (Ω)
104±5°
Periastron epoch (T)
34889.0±1.0 MJD
Argument of periastron (ω) (secondary)
283±5°
Details
σ Sco Aa1
Mass
18.4±5.4,[4]17.2-18.0[6]M☉
Radius
12.7±1.8[4]R☉
Luminosity
29,000±8,000,[4] 95,500[6]L☉
Surface gravity (log g)
3.85[4] cgs
Temperature
26,150±1,070,[4] 27,700[6] K
Metallicity [Fe/H]
−0.20±0.20[7] dex
Rotational velocity (v sin i)
25[8] km/s
Age
8.0±0.2,[9]8-10[6] Myr
σ Sco Aa2
Mass
11.9±3.1[4]M☉
Radius
11[4]R☉
Luminosity
16000±4000[4]L☉
Other designations
Alniyat, Al Niyat, Pekehāwani, 20 Scorpii, ADS 10009, CD-25 11485, FK5 607, HD 147165, HIP 80112, HR 6084, SAO 184336, WDS 16212-2536.[10]
Database references
SIMBAD
data
Sigma Scorpii (or σ Scorpii, abbreviated Sigma Sco or σ Sco), is a multiple star system in the constellation of Scorpius, located near the red supergiant Antares, which outshines it. This system has a combined apparent visual magnitude of +2.88,[2] making it one of the brighter members of the constellation. Based upon parallax measurements made during the Hipparcos mission, the distance to Sigma Scorpii is roughly 696 light-years (214 parsecs).[1] North et al. (2007) computed a more accurate estimate of 568+75 −59 light years (174+23 −18 parsecs).[4]
The system consists of a spectroscopic binary with components designated Sigma Scorpii Aa1 (officially named Alniyat/ælˈnaɪjæt/, the traditional name for the entire star system)[11][12] and a Beta Cephei variable) and Aa2; a third component (designated Sigma Scorpii Ab) at 0.4 arcseconds from the spectroscopic pair, and a fourth component (Sigma Scorpii B) at about 20 arcseconds.[13]
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SigmaScorpii (or σ Scorpii, abbreviated Sigma Sco or σ Sco), is a multiple star system in the constellation of Scorpius, located near the red supergiant...
the large blue area (IC 4604), Antares in the large yellow area and SigmaScorpii in the redish Sh2-9 area, with Messier 4 inbetween the latter two stars...
14.5–14.7 solar masses. τ Scorpii (Latinised to Tau Scorpii) is the star's Bayer designation. Tau Scorpii and SigmaScorpii together bore the traditional...
particular name corresponded to (e.g., Alniyat could refer to SigmaScorpii or Tau Scorpii). Some stars in entirely different constellations had the same...
Eridani Binary star system 2.89 2.84 Beta Canis Minoris Star 2.89 2.86 SigmaScorpii Quadruple star system 2.89 2.88 Epsilon Persei Binary star system 2...
Beta Canis Majoris and SigmaScorpii were found to be variable not long afterwards, Vesto Slipher noted in 1904 that SigmaScorpii's radial velocity was...
Brazilian territory in the northern hemisphere (and the State of Pará). The Sigma Octantis (south pole star) is small, but all the other stars turn around...
Bayer's Gamma and Omicron Scorpii, for example, were later reassigned from Scorpius to Libra and given the new names Sigma and Upsilon Librae.: p. 196 ...
state in Brazil called this star and λ Scorpii, through ι Scorpii, θ Scorpii, ν Scorpii, υ Scorpii and ρ Scorpii Taugi kusugu, "Taugi's fishing basket"...
handful of stars called recurrent novae, which include T Pyxidis and U Scorpii. An outburst of T Coronae Borealis was first recorded in 1866; its second...
atmospheric structure and fundamental parameters of the red supergiants AH Scorpii, UY Scuti, and KW Sagittarii". Astronomy & Astrophysics. 554: A76. arXiv:1305...
Gem), an A-type subgiant; Eta Bootis (η Boo), a G-type subgiant. Delta Scorpii (δ Sco), a B-type subgiant. Bright giants are stars of luminosity class...
of a New Data Set,” Astronomy & Astrophysics 363, November 2000, 947 18 Scorpii at SIMBAD - Ids - Bibliography - Image. Meléndez, Jorge; Ramírez, Iván...
Southern Cross, Epsilon Carinae (ε Car) in Carina, Lambda Scorpii (λ Sco) in Scorpius and Sigma Sagittarii (σ Sgr) in Sagittarius. After all twenty-four...
39m 18.11950s, declination −05° 13′ 29.9552″. It would be as bright as β Scorpii is in our sky. Canis Minor would obviously be missing its brightest star...
is located in the constellation of Scorpius, near the bright star Theta Scorpii. The star is in a crowded region of sky near the Galactic Center, and so...
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