Alniyat
HIP 80112; Sigma Sco; 20 Sco
HIP 80112; Sigma Sco; 20 Sco
DoubleStar
Sco
Visible
Level 3
Medium telescope (6-8") - Requires steady seeing
Physical Properties
Magnitude
2.89
Variable Type
Beta Cephei (Pulsating)
Spectral Type
B1 III
Star Color
White
(B-V 0.13)
Distance
683.4 ly
Position & Identifiers
RA
16h 21m 11.3s
Dec
-25° 35' 34.0"
Constellation
Sco
HR
6084
HIP
80112
Bayer
Sigma
Flamsteed
20 Sco
Variable ID
Sig Sco
Double Cat
10009
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Visibility
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Multiple Star System
Components
4
Component IDs
O
Separation
20.5″
Companion Mag
8.4
Companion Sp
B8V
Position Angle
269°
Star Colors
A: White
B: Blue-white
Discoverer
H 4 121
Eyepiece View
80x
Dawes: 1.9″
TFOV: 0.6°
Realistic = true angular size
Sep: 20.5″ · PA: 269° · N up, E left
Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 3.1″
Size Comparison
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Stellar Lifecycle
Spectral Classification
Hertzsprung-Russell Diagram
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Blackbody Spectrum
Stellar Absorption Spectrum
Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.
Stellar Notes
Beta C 2.94 - 3.06B. Multiple periods, 0.2468429, 0.239671, 8.2, and 33.1d. Surrounded by HII region. Primary | period varies in period of 23.2y with an amp. of 0.7 sec. Occultations indicate the variable has a 2.2 mag. fainter | companion at 0".49. The duplicity had been suspected from occultations as early as 1860. Orbital period probably over | 112 yrs. UV observations indicate temperature varies by 2510K and ratio max. to min. radius by 1.095.
B, 8.26V, +0.25(B-V), -0.23(U-B), B9.5V at 20", optical; vsini : 54k/s. The visual primary is triple: SB, 3.3, 5.3v, | sep. 0.0005" and 5.5v at 0.49", discovered by occultation.
ADS 10009A, 34.23d, K 34.0k/s, V0 +2.5k/s, asini 14.9.
Color excess E(B-V) = +0.40. Reddened star.
Sco OB2; Sco-Cen cluster; upper Sco region; HII region S9; in reflection nebula; assoc. Sco R1.
Stationary Ca lines. Although this star is an MK standard for class B1III, it is a variable, a multiple star, and is | situated in reflection nebulosity. Component A has also been classified as B2III and B2IV; component B as B9V, B9.5V, | and B8Vp. From scanner studies of composite spectra, Beavers (ApJS, 44, 489, 1980) finds ADS 10009A can be | resolved into O9.5 and B7 with a magnitude difference of 1.6V.
ADS 10009B, -6k/s.
Alniyat; Al Niyat. Name applies to pair with HR 6165.
Survey Image
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