The Heart Nebula (IC 1805) lies in Cassiopeia, about 7,500 light years away, and is a vast region of ionised hydrogen more than two hundred light years across. The nickname comes from its overall shape, which only reveals itself when you frame the whole thing.
It is lit by the open cluster Melotte 15 at its centre: a few dozen very young, very hot stars, some fifty times the mass of the Sun. Their ultraviolet radiation strips electrons from the hydrogen and makes it glow red, while their stellar winds hollow out the clouds and squeeze them into pillars and ridges where new stars are born.
The second frame goes right in there, into the heart of the Heart: the dust structures around Melotte 15, dark silhouettes against the burning gas.
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