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Theta Cassiopeiae — Star in Cassiopeia

Magnitude 4.3m Star Cassiopeia (Cas) Visible
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1Physical Properties

Magnitude 4.33
Variable Type Delta Scuti (Pulsating)
Spectral Type A7V
Star Color Yellow-white (B-V 0.17)
Distance 233 ly

2Position & Identifiers

RA 01h 11m 06.2s
Dec +55° 08' 59.0"
Constellation Cassiopeia (Cas)
HR 343
HIP 5542
HD 6961
SAO 22070
Bayer Theta
Flamsteed 33 Cas
SIMBAD

3How easy to spot?

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Equipment Bortle 3 Bortle 4 Bortle 5
Naked eye Medium+ Medium+ Medium
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 Sep – Nov (peak: Oct)

5Survey Image

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7

Size Comparison

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8

Compare Stars

9

Spectral Classification

10

Hertzsprung-Russell Diagram

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Read: The Hertzsprung-Russell Diagram — Reading Stars Like a Map
11

Stellar Lifecycle

12

Blackbody Spectrum

13

Stellar Absorption Spectrum

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

14

Stellar Fusion

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15Stellar Notes

Delta Sct?
Unresolved by speckle interferometry.
Hyades moving group.
Marfak. Name shared with HR 321.
16

Light Travel Time Machine

17

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 281
Medium+
Emission nebula — try an OIII filter
Emission Nebula mag 7.0 2.9° Cassiopeia
Phi Cas
Easy
Easy double, sep 134.1″
Double Star mag 4.98 3.3° Cassiopeia
NGC 457
Easy
Rich open cluster
Open Cluster mag 6.4 3.3° Cassiopeia
Shedir
HIP 3179; Alpha Cassiopeiae; 18 Cassiopeiae
Easy
Bright naked-eye star, mag 2.2
Star mag 2.23 4.5° Cassiopeia
1 Per
Hard+
Eclipsing binary, period 25.9d
Variable Star mag 5.52 5.8° Perseus
Show on Map

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