  The Hagedorn transition in non-commutative open string theory (NCOS) is
relatively simple because gravity decouples. For NCOS theories in no more than
five spacetime dimensions, the Hagedorn transition is second order, and the
high temperature phase involves long, nearly straight fundamental strings
separating from the D-brane on which the NCOS theory is defined. Above five
spacetime dimensions interaction effects become important below the Hagedorn
temperature. Although this complicates studies of the transition, we believe
that the high temperature phase again involves long strings liberated from the
bound state.
