Cepheids are pulsating variable stars with a periodic chromospheric response at UV wavelengths close to their minimum radius phase .
Recently , an X-ray variable signature was captured in observations during the maximum radius phase .
This X-ray emission came as a surprise and is not understood .
In this work , we use the modern astrophysical code , PLUTO , to investigate the effects of pulsations on Cepheid X-ray emission .
We run a number of hydrodynamic numerical simulations with a variety of initial and boundary conditions in order to explore the capability of shocks to produce the observed phase-dependent X-ray behavior .
Finally we use the Simulated Observations of X-ray Sources ( SOXS ) package to create synthetic spectra for each simulation case and link our simulations to observables .
We show that , for certain conditions , we can reproduce observed X-ray fluxes at phases 0.4–0.8 when the Cepheid is at maximum radius .
Our results span a wide range of mass-loss rates , 2 \times 10 ^ { -13 } – 3 \times 10 ^ { -8 } M _ { \odot } yr ^ { -1 } , and peak X-ray luminosities , 5 \times 10 ^ { -17 } – 1.4 \times 10 ^ { -12 } erg cm ^ { -2 } s ^ { -1 } .
We conclude that Cepheids exhibit two component emission with ( a ) shock waves being responsible for the phase dependent variable emission ( phases 0.2 - 0.6 ) , and ( b ) a separate quiescent mechanism being the dominant emission mechanism for the remaining phases .