Acamar, also known as Theta Eridani, is a binary star system. To be specific, you'll need to know which star you're asking about:

* Theta Eridani A: This is the primary star in the system. It's a blue-white main-sequence star with a surface temperature of approximately 10,500 Kelvin.

* Theta Eridani B: This is the secondary star, a red dwarf with a surface temperature of approximately 3,000 Kelvin.

So, depending on which star you're interested in, the surface temperature is either 10,500 Kelvin or 3,000 Kelvin.