I know this may not apply to SFC3, but in SFC2 the star's graphics are not dependent on the three star entries (CY, CR, CW) in shiplist.txt. You can delete these units from the roster and the sun still appears! Looking at the code with IDA, the game uses a rapid sequence of 4 bitmaps to create that fiery effect. The model of "yellowsun" doesn't appear to be used. There is no yellowsun.mod file. Perhaps the stars in shiplist.txt allow these units to "attack" ships that get too close with its solar weapon (whose chart hasn't been found).
SFC2CE has a serious flaw in the star graphics. Random images from ships are added to the sequence! It seems like an array is being read beyond its intended capacity of 4.