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Lambda Cephei — Star in Cepheus

Magnitude 5.0m Star Cepheus (Cep) Visible
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1Physical Properties

Magnitude 5.04
Range 5.00 - 5.08
Variable Type Variable (Unclassified)
Spectral Type O6I(n)fp supergiant
Star Color Yellow-white (B-V 0.25)
Distance 544 ly

2Position & Identifiers

RA 22h 11m 30.7s
Dec +59° 24' 52.0"
Constellation Cepheus (Cep)
HR 8469
HIP 109556
HD 210839
SAO 34149
Bayer Lambda
Flamsteed 22 Cep
SIMBAD

3How easy to spot?

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Equipment Bortle 3 Bortle 4 Bortle 5
Naked eye Medium Medium Hard+
50mm finder Easy Easy Easy
150mm scope Easy Easy Easy
Easy Medium Hard Very hard Impossible

Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs

4Visibility

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Best season Jul – Sep (peak: Aug)

5Survey Image

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6

Size Comparison

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7

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8

Spectral Classification

9

Hertzsprung-Russell Diagram

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Read: The Hertzsprung-Russell Diagram — Reading Stars Like a Map
10

Stellar Lifecycle

11

Blackbody Spectrum

12

Stellar Absorption Spectrum

Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.

13

Stellar Fusion

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14Stellar Notes

Polarization variable in intervals of about a day.
Runaway star from Cep OB2; in broken HII region within a reflection nebula.
Also classified O6f, O6ef and O6.5If; uv 1394 absorption very strong, 1548 absorption strong, emission very strong.
15

Light Travel Time Machine

16

Relativistic Travel

Nearby in the Sky

Other targets within a few degrees — pan your scope a little and keep exploring.

Visibility scores assume a 150 mm Newton at Bortle 4.

NGC 7261
Easy
Open cluster
Open Cluster mag 8.4 1.8° Cepheus
14 Cep
Easy
Hot blue O-type star
Star mag 5.56 1.9° Cepheus
Delta Cep
Medium+
Pulsating variable, period 5.4d
Variable Star mag 3.75 2.5° Cepheus
19 Cep
Easy
Hot blue O-type star
Star mag 5.11 3.0° Cepheus
Sh2-155
C9
Medium
Emission nebula — try an OIII filter
Emission Nebula mag 7.7 6.4° Cepheus
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