Iota Geminorum — Double Star in Gemini

Magnitude 3.8^m DoubleStar Gemini (Gem) Visible

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1Physical Properties

Magnitude 3.79

Spectral Type G9IIIb bright giant

Star Color Orange (B-V 1.03)

Distance 120 ly

2Position & Identifiers

RA 07h 25m 43.6s

Dec +27° 47' 53.0"

Constellation Gemini (Gem)

HR 2821

HIP 36046

HD 58207

SAO 79374

Bayer Iota

Flamsteed 60 Gem

3How easy to spot?

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Equipment	Bortle 3	Bortle 4	Bortle 5
Naked eye Naked eye	Easy	Medium+	Medium+
50 mm finder 50mm finder	Easy	Easy	Easy
150 mm telescope 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 Dec – Feb (peak: Jan)

5Multiple Star System

Separation 0.1″

Companion Mag 4.7

Position Angle -1°

Star Colors A: Orange

Discoverer OCC 132

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7

Size Comparison

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8

Compare Stars

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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

Alternative Names

Propus, a name more commonly applied to HR 2216.

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.

Open Cluster mag 9.0 4.2° Gemini

HIP 36850; Alpha Geminorum; 66 Geminorum

Easy double, sep 5.7″

Double Star mag 1.98 4.5° Gemini

HIP 35550; Delta Geminorum; 55 Geminorum

Colorful double, sep 5.5″

Double Star mag 3.53 6.0° Gemini

Small bright planetary nebula

Planetary Nebula mag 9.2 6.9° Gemini

Pulsating variable, period 10.1d

Variable Star mag 3.79 8.7° Gemini

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