V640 Cassiopeiae — Double Star in Cassiopeia

Observable Double Star Fair (26/100)

Sep: 1.5", Companion: mag 7.3

Magnitude 6.0^m DoubleStar Cassiopeia (Cas) Visible

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Observe

1Physical Properties

Magnitude 5.96

Range 5.97 - 5.98

Period 48 days

Variable Type R

Spectral Type G5V

Star Color Orange (B-V 0.67)

Distance 69 ly

2Position & Identifiers

RA 00h 06m 16.0s

Dec +58° 26' 12.0"

Constellation Cassiopeia (Cas)

HR 5

HIP 518

HD 123

SAO 21085

Variable ID V640 Cas

Double Cat 61

3How easy to split?

Primary 6.0 mag Companion 7.3 mag Separation 1.5″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Hard	Hard	Hard
150 mm Newton 150mm Newt.	Medium	Medium	Medium
Celestron C8 (203 mm SCT) C8 203mm	Medium+	Medium+	Medium+

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)

5Light Curve

6Multiple Star System

Separation 1.5″

Companion Mag 7.3

Companion Sp G8V

Position Angle 8°

Star Colors A: Orange B: Orange

Discoverer STF3062

Notes

6.43 dG4, 7.19 dG8, 106.83y, a = 1.432". Component B has possible invisible companion, period 6.9y.

Separation over time

Period: 106.7 y Eccentricity: 0.450 Now: 1.5", PA 17° -0.10" in 5 years

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

Eyepiece View

Telescope Eyepiece

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80x Dawes: 1.9″ TFOV: 0.6°

Seeing

Scale Realistic = true angular size

A: 6.0 · B: 7.3 · Sep: 1.5″ · PA: 8° · N up, E right

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

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7

Size Comparison

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8

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9

Spectral Classification

10

Hertzsprung-Russell Diagram

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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

Variable Star

Amp. 0.066V, 1.0819d.

Dynamical

0.051".

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.

HIP 746; Beta Cassiopeiae; 11 Cassiopeiae

Bright naked-eye star, mag 2.3

Star mag 2.27 0.8° Cassiopeia

Variable star, range 5.9–6.3

Variable Star mag 6.00 1.8° Cassiopeia

Galaxy mag 10.3 2.0° Cassiopeia

Semi-regular variable, range 6.8–7.7

Double Star mag 6.90 2.0° Cassiopeia

Caroline's Rose

Rich open cluster

Open Cluster mag 6.7 2.1° Cassiopeia

Easy double, sep 3.1″

Double Star mag 4.88 2.9° Cassiopeia

Tight double — a rewarding split at 1.5″

Double Star mag 5.43 4.3° Cassiopeia

Colorful double, sep 75.0″

Double Star mag 4.91 4.7° Cassiopeia

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