21 Oph

HIP 82480; 21 Oph DoubleStar Ophiuchus (Oph) Visible Level 5 Expert level - Requires steady seeing

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Physical Properties

Magnitude 5.51

Spectral Type A2V s

Star Color White (B-V 0.05)

Distance 155 ly

Position & Identifiers

RA 16h 51m 24.9s

Dec +01° 12' 58.0"

Constellation Ophiuchus (Oph)

HR 6255

HIP 82480

Flamsteed 21 Oph

Double Cat 10230

Visibility

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Multiple Star System

Separation 0.7″

Companion Mag 7.3

Position Angle 309°

Star Colors A: White B: Yellow-white

Discoverer STT 315

Eyepiece View

Telescope Eyepiece

80x Dawes: 1.9″ TFOV: 0.6°

Seeing

Scale Realistic = true angular size

Sep: 0.7″ · PA: 309° · N up, E left

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

Size Comparison

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Stellar Lifecycle

Spectral Classification

Hertzsprung-Russell Diagram

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Blackbody Spectrum

Stellar Absorption Spectrum

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Stellar Fusion

Stellar Notes

Group/Cluster

Sirius group?

Dynamical

0.005".

Light Travel Time Machine

Relativistic Travel

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