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Delta Equulei — Star in Equuleus

Star Equuleus (Equ) Visible
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1Physical Properties

Magnitude 4.49
Spectral Type F5V+G0V
Star Color Yellow (B-V 0.50)
Distance 56 ly

2Position & Identifiers

RA 21h 14m 28.9s
Dec +10° 00' 25.0"
Constellation Equuleus (Equ)
HR 8123
HIP 104858
HD 202275
Bayer Delta
Flamsteed 7 Equ
Double Cat 14773
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 Jul – Sep (peak: Aug)

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6

Size Comparison

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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

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14Stellar Notes

AB 5.2 F7V, 5.3 F7V, 5.70y, a = 0.26". Combined mag., colors. Component C, 9.5v at 48" optical.
5.70y D, K 24.9k/s, V0 -15.2k/s, asini 633. Resolved by speckle interferometry 1983.93, sep. 0.41".
0.062".
15

Light Travel Time Machine

16

Relativistic Travel

Survey Image

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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.

Gamma Equ
Easy
Easy double, sep 335.0″
Double Star mag 4.69 1.0° Equuleus
M15
Great Pegasus Cluster
Easy
Large bright globular cluster
Globular Cluster mag 6.2 4.4° Pegasus
AG Peg
Easy
Mira-type variable, range 6.0–9.4
Variable Star mag 6.00 9.3° Pegasus
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Equuleus
Mythology, bright stars, and deep-sky highlights.
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The Hertzsprung-Russell Diagram — Reading Stars Like a Map
The HR diagram turns the night sky into a physics map: every named star has a spot, every spot tells you mass, age, and fate. A guide for amateur observers.
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