Stars range in (surface) temperature from about 3500 K to 50,000 K
Their temperatures correlate with mass and luminosity (massive stars are hot and very bright): a 50,000 K star has a million times the luminosity (power output in Watts) of the Sun (Tsun = 6000 K)
Stars hotter than about 8000 do not have convective outer layers - no convection - no dynamo - no hot corona…
…no x-rays