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Sigma Herculis — Star in Hercules

Star Hercules (Her) Visible
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1Physical Properties

Magnitude 4.20
Spectral Type B9V
Star Color Blue-white (B-V -0.01)
Distance 326 ly

2Position & Identifiers

RA 16h 34m 06.2s
Dec +42° 26' 13.0"
Constellation Hercules (Her)
HR 6168
HIP 81126
HD 149630
Bayer Sigma
Flamsteed 35 Her
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 Apr – Jun (peak: May)

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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

Sep. 0.067". Noted as double by speckle interferometry in 1971-2, unresolved at Mayall 4-meter in 1976. Spectrum | double-lined. Resolved by speckle observations 1986.45 (Blazit et al. 1987, A&AS, 71, 57).
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.

30 Her
Easy
Mira-type variable, range 4.3–6.3
Variable Star mag 5.04 1.2° Hercules
NGC 6239
Hard+
Barred spiral galaxy
Galaxy mag 12.3 3.0° Hercules
NGC 6229
Easy
Globular cluster — dense ball of ancient stars
Globular Cluster mag 9.4 5.6° Hercules
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