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Theta1,2 Eridani

Proper NameAcamar (properly the name of the Theta1 component of this binary system)
Bayer DesignationTheta1,2 Eridani
Flamsteed NumberNone
HR (BSC)897 (Theta1 Eridani)
898 (Theta2 Eridani)
HD18622 (Theta1 Eridani)
18623 (Theta2 Eridani)
Right Ascension2h 59m 4s
Declination-40° 13' 20"
Distance160 light years
49 parsecs
MagnitudeApparent: +3.2 (Theta1 Eridani), +4.3 (Theta2 Eridani)
Absolute: -0.3 (Theta1 Eridani), +0.8 (Theta2 Eridani)
Spectral ClassA5IV White Subgiant (Theta1 Eridani)
A1V White Main Sequence Star (Theta2 Eridani)
Optimum VisibilityNovember
NotesTheta Eridani is a widely-spaced binary star, of which the traditional name Acamar is formally applied to the Theta1 subgiant component. There is reason to think that this subgiant - which is beginning its transition to the red giant phase of its existence - has another star in a much closer orbit, making Acamar a multiple system.

A binary star in the River Eridanus. Both components are hot white, A-type stars, but one is a subgiant while its companion is a smaller dwarf star. The entire system lies nearly 170 light years from Earth.


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