21 Per
Observable Variable Star
Good (54/100)
Range: 5.03 - 5.14, Period: 2.9d, Type: ACV
HIP 13775; 21 Per
VariableStar
Per
Visible
Level 3
Medium telescope (6-8") - Monitor brightness changes
Physical Properties
Magnitude
5.11
Range
5.03 - 5.14
Period
2.884 days
Variable Type
Alpha2 CVn (Magnetic Rotating)
Spectral Type
B9pSi
Star Color
Blue-white
(B-V -0.01)
Distance
1087.2 ly
Position & Identifiers
RA
02h 57m 17.3s
Dec
+31° 56' 03.0"
Constellation
Per
HR
873
HIP
13775
Flamsteed
21 Per
Variable ID
LT Per
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Visibility
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Light Curve
Comparison Stars for 21 Per (5.0–5.1)
Nearby stable stars for estimating brightness (AAVSO)
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Multiple Star System
Separation
1.1″
Companion Mag
9.8
Position Angle
46°
Star Colors
A: Blue-white
B: Orange
Discoverer
DCH 116
Eyepiece View
80x
Dawes: 1.9″
TFOV: 0.6°
Realistic = true angular size
Sep: 1.1″ · PA: 46° · 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
Alpha CV 5.03 - 5.14V, 2.88422d, same for RV and line-intensities. Also var. magnetic field and H-lines. Rotating | spotted star.
2.88d.
Member moving cluster in Perseus.
Underabundance of magnesium and oxygen.
Survey Image
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