larger outflow speeds, and become more ionized. In the highest activity cases, the temperature at the upper boundary of the simulation stops increasing with increasing activity and instead decreases due to adiabatic cooling, which can cause a negative temperature gradient in hydrodynamic outflows (@Tian08; see also Fig. 1 of @Johnstone15letter). This can be best seen in the upper panel of Fig. \[fig:hydrogridFx\], where the maximum temperature of $\sim$20,000 K is reached at an input X-ray flux of $\sim$250 erg s$^{-1}$ cm$^{-2}$. The sonic point altitude, shown in the lower panel of Fig. \[fig:hydrogridFx\], gets closer to the planet as the input XUV flux increases due to the more rapid acceleration of the wind, but at very high activity cases appears to become approximately independent of activity with a value of $\sim$500 km. The ionization fraction at the upper boundary continues to increase with increasing activity, even at very high activity level, and in the most active case considered is 93% meaning that as it flows away from the planet, the gas is almost entirely ionized.

In Fig. \[fig:MdotgridFx\], I show the outward hydrodynamic mass flux as a function of input stellar X-ray flux. As expected, higher stellar activity cases have 