The X-ray spectra of intermediate polars can be modelled to give a direct measurement of white dwarf mass. Here we fit accretion column models to NuSTAR spectra of three intermediate polars; V709 Cas, NY Lup and V1223 Sgr in order to determine their masses. From fits to 3-78 keV spectra, we find masses of $M_{ \rm WD}=0.88^{ +0.05}_{ -0.04}M_{ \odot}$, $1.16^{ +0.04}_{ -0.02}M_{ \odot}$ and $0.75\pm0.02M_{ \odot}$ for V709 Cas, NY Lup and V1223 Sgr, respectively. Our measurements are generally in agreement with those determined by previous surveys of intermediate polars, but with typically a factor $\sim2$ smaller uncertainties. This work paves the way for an approved NuSTAR Legacy Survey of white dwarf masses in intermediate polars.
Categories: astro-ph.HE