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34 Cephei — Double Star in Cepheus

Observable Double Star Excellent (60/100)

Sep: 3.5", Companion: mag 7.3

Magnitude 4.8m DoubleStar Cepheus (Cep) Visible
Star Map
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Observe

1Physical Properties

Magnitude 4.75
Spectral Type K0III giant
Star Color Orange (B-V 0.84)
Distance 136 ly

2Position & Identifiers

RA 23h 18m 37.5s
Dec +68° 06' 42.0"
Constellation Cepheus (Cep)
HR 8872
HIP 115088
HD 219916
SAO 20554
Flamsteed 34 Cep
Double Cat 16666
SIMBAD

3How easy to split?

Primary 4.8 mag Companion 7.3 mag Separation 3.5″
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Telescope Bortle 3 Bortle 4 Bortle 5
80mm refr. Medium Medium Medium
150mm Newt. Easy Easy Easy
C8 203mm Easy Easy Easy
Easy Medium Hard Very hard Impossible

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

4Visibility

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Best season Aug – Oct (peak: Sep)

5Multiple Star System Triple

Components 3 (triple)
Component IDs AB
Separation 3.5″
Companion Mag 7.3
Position Angle 223°
Star Colors A: Orange
Discoverer STF3001
AB 4.86 K0III, 7.13 F6V, 796.16y, a = 2.991".

Separation over time

Period: 2198.7 y Eccentricity: 0.914 Now: 3.5", PA 224° + 0.03" in 5 years
0.00" 1.0" 2.1" 3.1" 4.2" 2025 2030 2035 2040 2045 3.5"

Apparent separation over time, computed from ORB6 orbital elements. Steep curves indicate fast-changing pairs — catch them while they're splittable.

Eyepiece View

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80x Dawes: 1.9″ TFOV: 0.6°
Realistic = true angular size
N E 223°

A: 4.8 · B: 7.3 · Sep: 3.5″ · PA: 223° · N up, E right

Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 2.3″

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6

Size Comparison

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7

Compare Stars

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

Discover

14Stellar Notes

0.018".
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 7762
Easy
Open cluster
Open Cluster mag 10.0 2.9° Cepheus
Sh2-155
C9
Medium
Emission nebula — try an OIII filter
Emission Nebula mag 7.7 5.9° Cepheus
6 Cas
Hard+
Tight double — a rewarding split at 1.5″
Double Star mag 5.43 6.7° Cassiopeia
21 Cas
Hard+
Eclipsing binary, period 4.5d
Variable Star mag 5.66 9.6° Cassiopeia
Show on Map

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