HD 259440 is a B0pe star that was proposed as the optical counterpart to the \gamma -ray source HESS J0632+057 .
Here we present optical spectra of HD 259440 acquired to investigate the stellar parameters , the properties of the Be star disk , and evidence of binarity in this system .
Emission from the H \alpha line shows evidence of a spiral density wave in the nearly edge-on disk .
We find a best fit stellar effective temperature of 27500 - 30000 K and a log surface gravity of 3.75 - 4.0 , although our fits are somewhat ambiguous due to scattered light from the circumstellar disk .
We derive a mass of 13.2 - 19.0 M _ { \odot } and a radius of 6.0 - 9.6 R _ { \odot } .
By fitting the spectral energy distribution , we find a distance between 1.1 - 1.7 kpc .
We do not detect any significant radial velocity shifts in our data , ruling out orbital periods shorter than one month .
If HD 259440 is a binary , it is likely a long period ( > 100 d ) system .