Acamar
HIP 13847; Theta1 Eri
Sep: 8.2", Companion: mag 4.1
Physical Properties
Position & Identifiers
Visibility
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Multiple Star System
Eyepiece View
Sep: 8.2″ · PA: 90° · N up, E left
Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 3.1″
Size Comparison
Stellar Lifecycle
Spectral Classification
Hertzsprung-Russell Diagram
Blackbody Spectrum
Stellar Absorption Spectrum
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Stellar Notes
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About Acamar
Description
Acamar is a binary star system at magnitude 3.24 in Eridanus, consisting of two white stars (A4III and A1V) separated by about 8 arcseconds. Located about 161 light-years from Earth, the pair makes one of the finest double stars in the southern sky.
Observing Tips
Acamar lies in the middle of Eridanus's long winding course. A small telescope reveals a beautiful pair of nearly white stars. Before Achernar was known to European astronomers, Acamar marked the end of the River. Best observed November through February.
History
The name Acamar comes from the Arabic 'akhir al-nahr,' meaning 'the end of the river' — the same root as Achernar. For ancient Greek and Arabic observers at northern latitudes, Acamar was the southernmost visible star of Eridanus, and thus the river's end.
Fun Facts
Acamar once marked the end of Eridanus for classical astronomers who could not see farther south. The discovery of the more southerly Achernar pushed the river's terminus farther toward the south celestial pole.