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Dalim — Double Star in Fornax

HIP 14879; Alpha Fornacis

Observable Double Star Excellent (60/100)

Sep: 5.5", Companion: mag 7.2

Magnitude 3.9m DoubleStar Fornax (For) Visible
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About Dalim

Description

Dalim, Alpha Fornacis, is the brightest star in the faint southern constellation Fornax. It is an F-type subgiant of spectral class F6 V about 46.4 light-years away — a relatively nearby bright star. Dalim is a close visual binary, with a magnitude 7 companion orbiting every 269 years at a current separation of 5 arcseconds. Combined system magnitude is 3.87.

Observing Tips

Dalim lies in southern Fornax, an inconspicuous constellation south of Eridanus. Despite being the constellation's alpha star, Fornax is so faint overall that Dalim is sometimes overlooked. The 5-arcsecond double is a lovely pair in a 3-inch scope at 100x. Best observed October through February.

History

The name Dalim was proposed and adopted by the IAU in 2017. Its etymology is somewhat uncertain but is believed to derive from a medieval Arabic source for this region.

Fun Facts

Fornax is one of several 18th-century "furnace" constellations — along with Antlia (the air pump), Reticulum (the reticle), and Microscopium — created by Nicolas-Louis de Lacaille to fill gaps in the southern sky with scientific-instrument themes. Dalim's modest brightness reflects the general lack of bright stars in these Lacaille constellations.

Observe

1Physical Properties

Magnitude 3.87
Spectral Type F6V
Star Color Yellow (B-V 0.52)
Distance 46 ly

2Position & Identifiers

RA 03h 12m 04.3s
Dec -28° 59' 13.0"
Constellation Fornax (For)
HR 963
HIP 14879
HD 20010
SAO 168373
Bayer Alpha
Double Cat 2402

3How easy to split?

Primary 3.9 mag Companion 7.2 mag Separation 5.5″
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Telescope Bortle 3 Bortle 4 Bortle 5
80mm refr. Medium 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 Oct – Dec (peak: Nov)

5Multiple Star System

Separation 5.5″
Companion Mag 7.2
Position Angle 301°
Star Colors A: Yellow B: Orange
Discoverer HJ 3555
3.9 F8IV, 6.5 G7V, 314y, a = 4.367". Combined mag., colors.

Separation over time

Period: 268.2 y Eccentricity: 0.737 Now: 5.5", PA 301° + 0.05" in 5 years
0.00" 1.6" 3.2" 4.8" 6.4" 2025 2030 2035 2040 2045 5.5"

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 301°

A: 3.9 · B: 7.2 · Sep: 5.5″ · PA: 301° · N up, E right

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

Explore

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Size Comparison

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Compare Stars

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Spectral Classification

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Hertzsprung-Russell Diagram

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Stellar Lifecycle

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Blackbody Spectrum

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Stellar Absorption Spectrum

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

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Stellar Fusion

Discover

15Stellar Notes

ADS 2402B, 7.0 - 9.03v.
0.070".
Fornacis; 12 Eri in For.
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Light Travel Time Machine

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Relativistic Travel

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