Observed optical excess is ~6-7 (Walter & Lattimer, 2002)
One
component model which requires a surface emissivity in the
X-ray band which is lower than a black body. Solid and dotted
curves represent the absorbed and unabsorbed model spectra,
respectively. Burwitz et al, 2002.
€ Depression factor
in the X-ray » 0.15
€ Optical excess » 6.67