Once upon a time all of the DBS companies (except for DirecTV/USSB) had the word "star" in the last part of their name - Echostar, Alphastar and Primestar, so people used to abbreviate them E*, A* and P* in the discussion forums to save room and keystrokes. To be fair, DirecTV got labeled D*. I guess we could call Voom "V*" too.
As you know, A* and P* are no more, so we only have D* and E* left (and now we have V*).
A consise chart with dates of various companies launching and dying can be found here (edit: but this chart appears to no longer be maintained - it only goes up to 2001).
Alphastar started in July 1996 and ceased sometime in 1997.