NGC 7635 is formed by the intense stellar wind (a stream of charged particles) from a massive (O- or B-type)…

NGC 7635 is formed by the intense stellar wind (a stream of charged particles) from a massive (O- or B-type) star, blowing the gas into a spherical shell. This radiates ultraviolet radiation and ionizes the surrounding hydrogen, producing the emission nebula's light. M97 is a Sun-like star that has evolved into a late red giant, ejecting its outer layers of gas, leaving behind a hot core that ionizes these gases. NGC 2359 is centered on a Wolf–Rayet star (an extremely massive star in its late stage). Wolf–Rayet stars have extremely high stellar wind speeds (2000–3000 km/s) and kinetic energy far greater than that of O-type main-sequence stars. Massive stars are violently stripped of their outer layers before they explode as supernovae.