Acamar, also known as Theta Eridani, is a double star, consisting of a +3.2 magnitude bright main star of the spectral class A4 and a companion of the spectral class A1 of magnitude +4.3.  It is located 120 light years from Earth, at the southern end of the constellation Eridanus ('the River'), just before its southernmost tip at Achenar.

In the Star Trek The Next Generation episode "The Vengeance Factor" , Acamar  III was the third planet in the Acamar system and homeworld of the Acamarian species. The Acamarians suffered through one hundred years of war between rival clans and the Enterprise-D was involved in efforts to reconcile the Acamarians with the Gatherers, the last renegade clans.

The constellation Eridanus