Based on the info you posted, it's hard to say what model it is.
If it looks like a slightly scaled-down 1911, it is a B-series pistol. The Model B, BS, and B Super look like a Government Model; the BM, BKM, and BKS look like a Commander. The model designation is usually- albeit not always!- stamped on the butt. It may be a small letter above the serial number.
If it's a smallish single-action pistol that looks kinda like a cross between a CZ 75 and a SIG P229, it's probably a Model 43 Firestar (single-stack) or Model 243 Firestar Plus (double-stack).
Mags for these Star pistols are made by Triple K, but I've been warned that production is intermittent, so availability can be spotty. Also, if the pistol is full-size B series, there are two types of mags depending on whether or not the pistol has a notch in the butt at the front of the mag well.
Star also made a series of large DA/SA double-stack pistols- the Models 28, 30, and 31- that look roughly like squared-off CZ 75's, but most of these are marked on the frame rather than the slide, so I'm guessing it's not one of these.
More here: http://star-firearms.com/firearms/index.shtml