Caldwell 40 is an unbarred lenticular galaxy in Leo. In terms of shape, lenticular galaxies are somewhere between spiral galaxies and elliptical galaxies. They have the disk of a spiral galaxy but they don’t have well defined spiral arms. They also have lost or used up most of their gas and so have very little star formation.

This one is about 75 million light years away. For some reason it has two NGC designations, NGC 3626 and NGC 3632.

This is 43h 25m of HaLRGB data. For all the technical details, see astrobin.