Abstract
We propose a new interpretation for the low radial velocity of He II emission line in the Galactic supersoft X-ray source RX J0019.8+2156 based on a 2-D numerical simulation of dynamical mass transfer in binary systems. A more massive main-sequence (MS) companion of
∼ 2.0 M
sun is derived for a ∼ 0.6 M
sun white dwarf (WD) primary.
