x y is by default interpreted as Star[x, y].
Used to denote convolution and generalized forms of multiplication.
Sometimes used in prefix form to indicate dual.
Not the same as \[SixPointedStar] or \[RawStar].
\[RawStar] is the character entered for superscripts.
See The Mathematica Book: Section 3.10.1 and Section 3.10.4.
See also: \[Times] , \[Cross] .