Tau Arietis — Double Star in Aries

HIP 15737; Tau2 Arietis; 63 Arietis

Magnitude 5.1^m DoubleStar Aries (Ari) Visible

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Observe

1Physical Properties

Magnitude 5.09

Spectral Type K3III giant

Star Color Red (B-V 1.24)

Distance 408 ly

2Position & Identifiers

RA 03h 22m 45.2s

Dec +20° 44' 31.0"

Constellation Aries (Ari)

HR 1015

HIP 15737

HD 20893

SAO 75899

Bayer Tau2

Flamsteed 63 Ari

SIMBAD Wikipedia

3How easy to spot?

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Equipment	Bortle 3	Bortle 4	Bortle 5
Naked eye Naked eye	Medium	Hard+	Hard+
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 Oct – Dec (peak: Nov)

5Multiple Star System

Separation 0.2″

Companion Mag 8.1

Position Angle 299°

Star Colors A: Red

Discoverer HDS 423

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Size Comparison

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Spectral Classification

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Hertzsprung-Russell Diagram

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10

Stellar Lifecycle

11

Blackbody Spectrum

12

Stellar Absorption Spectrum

Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.

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Stellar Fusion

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Light Travel Time Machine

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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 13914; Epsilon Arietis; 48 Arietis

Tight double — a rewarding split at 1.3″

Double Star mag 4.63 5.5° Aries

HIP 17579; 21 Tauri

Easy double, sep 149.6″

Double Star mag 5.76 6.6° Taurus

Pleiades, Seven Sisters or Subaru

Open Cluster mag 1.6 6.6° Taurus

HIP 17702; Eta Tauri; 25 Tauri

Easy double, sep 117.6″

Double Star mag 2.87 6.6° Taurus

HIP 13654; Rho2 Arietis; 45 Arietis

Semi-regular variable, range 5.6–6.0

Variable Star mag 5.91 6.8° Aries

Galaxy mag 11.7 6.9° Aries

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