31 Cyg
HIP 99675; 31 Cyg
DoubleStar
Cyg
Visible
Level 3
Medium telescope (6-8") - Requires steady seeing
Physical Properties
Magnitude
3.79
Variable Type
Eclipsing Binary (Algol-type)
Spectral Type
K2II+...
Star Color
Red
(B-V 1.28)
Distance
871.0 ly
Position & Identifiers
RA
20h 13m 37.9s
Dec
+46° 44' 29.0"
Constellation
Cyg
HR
7735
HIP
99675
Flamsteed
31 Cyg
Variable ID
V695 Cyg
Double Cat
13554
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Visibility
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Multiple Star System
Components
6
Component IDs
AD
Separation
36.2″
Companion Mag
13.4
Companion Sp
B3V
Position Angle
327°
Star Colors
A: Red
B: Blue
Discoverer
HJ 1495
Eyepiece View
80x
Dawes: 1.9″
TFOV: 0.6°
Realistic = true angular size
Sep: 36.2″ · PA: 327° · 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
ADS 13554A, EA 3.77 - 3.88V, 3784.3d. Amp. varies strongly with wavelength. C = NSV 12931, 6.98V.
Component C, 6.99V, -0.14(B-V), -0.58(U-B) B5V, vsini : 25k/s, at 107" fixed. AP probably single star.
ADS 13554A, 3784.3d, K 14.0k/s, V0 -7.7k/s, msin3i 9.19, asini 711. Unresolved by speckle interferometry. SKYLAB | indicates cool star with hot companion. vsini of secondary 80k/s.
Also classified K4Iab + B4IV-V.
See HR 7730.
Survey Image
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