Rich_121

Historical note: we use the phrase "space-time" because in Einstein's relativity theories, both space (3 dimensions) and time (1 dimension) get treated in an analogous way, mathematically. Therefore, it was convenient to have a phrase with which to refer to both space and time dimensions at once. Hence, Space-Time.

Yep, agree with the others. Alpha Centauri is a closely-orbiting binary system, with a third star (proxima) which is thought to also be gravitaitonally bound to the same system (hence, trinary overall). And either way, proxima is closest.