21 Sgr
Observable Double Star
Fair (31/100)
Sep: 1.7", Companion: mag 7.4
HIP 90289; 21 Sgr
DoubleStar
Sgr
Visible
Level 5
Expert level - Requires steady seeing
Physical Properties
Magnitude
4.81
Spectral Type
K2II
Star Color
Red
(B-V 1.31)
Distance
250.9 ly
Position & Identifiers
RA
18h 25m 21.0s
Dec
-20° 32' 30.0"
Constellation
Sgr
HR
6896
HIP
90289
Flamsteed
21 Sgr
Double Cat
11325
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Visibility
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Multiple Star System
Separation
1.7″
Companion Mag
7.4
Companion Sp
A1V
Position Angle
280°
Star Colors
A: Red
B: White
Discoverer
JC 6
Eyepiece View
80x
Dawes: 1.9″
TFOV: 0.6°
Realistic = true angular size
Sep: 1.7″ · PA: 280° · N up, E left
Unresolved · 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
Companion is A5:.
Red star Pleiades group.
0.006".
Survey Image
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