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HIP 84720 — Double Star in Ara

Observable Double Star Excellent (63/100)

Sep: 11.1", Companion: mag 8.9

Magnitude 5.5m DoubleStar Ara Visible
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1Physical Properties

Magnitude 5.48
Spectral Type G8-K0V
Star Color Orange (B-V 0.80)
Distance 25 ly

2Position & Identifiers

RA 17h 19m 03.2s
Dec -46° 38' 02.0"
Constellation Ara
HR 6416
HIP 84720
HD 156274
SAO 227816
SIMBAD

3How easy to split?

Primary 5.5 mag Companion 8.9 mag Separation 11.1″
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Telescope Bortle 3 Bortle 4 Bortle 5
80mm refr. Easy Medium+ Medium+
150mm Newt. Easy Easy Easy
C8 203mm Easy Easy Easy
Easy Medium Hard Very hard Impossible

Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs

4Visibility

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Best season May – Jul (peak: Jun)

5Multiple Star System Quadruple

Components 4 (quadruple)
Component IDs AB
Separation 11.1″
Companion Mag 8.9
Position Angle 259°
Star Colors A: Orange B: Red
AB 5.53 G8V, 8.65 M0V, 693.24y, a = 10.415", or 2205y, a = 23.90". Various published orbits range from 242 to 2205y. | Combined mag., colors.

Separation over time

Period: 846.6 y Eccentricity: 0.809 Now: 11.1", PA 260° + 0.32" in 5 years
0.00" 3.5" 7.1" 10.6" 14.2" 2025 2030 2035 2040 2045 11.1"

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

Eyepiece View

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80x Dawes: 1.9″ TFOV: 0.6°
Realistic = true angular size
N E 259°

A: 5.5 · B: 8.9 · Sep: 11.1″ · PA: 259° · N up, E right

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

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6

Size Comparison

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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

0.117".
Comp. B, +21k/s.
15

Light Travel Time Machine

16

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.

NGC 6352
Easy
Globular cluster — dense ball of ancient stars
Globular Cluster mag 8.2 2.1° Ara
IC 4651
Easy
Rich open cluster
Open Cluster mag 6.9 3.4° Ara
Sargas
HIP 86228; Theta Scorpii
Easy
Easy double, sep 6.5″
Double Star mag 1.87 4.9° Scorpius
V861 Sco
Medium
Eclipsing binary, period 7.8d
Variable Star mag 6.15 7.1° Scorpius
V918 Sco
Hard+
Hot blue O-type star
Double Star mag 5.47 8.5° Scorpius
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