Planetary nebulae are some of the most beautiful objects in the universe.
They are formed when an intermediate mass star no longer has enough hydrogen to sustain nuclear fusion. The energy from nuclear fusion cannot counter gravitational forces and the star collapses. This causes the core of the star to heat up, and the outer shell of the star is ejected. The exposed core emits extraordinarily intense ultraviolet radiation which ionises the expelled shell, causing it to emit light - primarily at the wavelengths of hydrogen alpha and oxygen III.
Click on each image for more details.
They are formed when an intermediate mass star no longer has enough hydrogen to sustain nuclear fusion. The energy from nuclear fusion cannot counter gravitational forces and the star collapses. This causes the core of the star to heat up, and the outer shell of the star is ejected. The exposed core emits extraordinarily intense ultraviolet radiation which ionises the expelled shell, causing it to emit light - primarily at the wavelengths of hydrogen alpha and oxygen III.
Click on each image for more details.
Abell 5
Abell 13
Abell 22
Abell 29
Abell 34
Abell 59
Abell 71
Abell 80
Abell 82
Abell 6
Abell 24
Abell 30
Abell 36
Abell 61
Abell 74
Abell 7
Abell 16
Abell 28
Abell 31
Abell 39
Abell 50
Abell 62
Abell 78
Abell 12
Abell 20
Abell 33
Abell 45
Abell 56
Abell 66
Abell 79
Abell 84