NGC 4639

Barred spiral galaxy NGC 4639’s spiral arms are sprinkled with bright regions of active star formation. But this galaxy also conceals a dark secret in its core — a massive black hole that is consuming the surrounding gas. This is known as an active galactic nucleus (AGN); NGC 4639 is in fact a very weak example of an AGN, demonstrating that AGNs exist over a large range of activity, from galaxies like this one to distant quasars, where the parent galaxy is almost completely dominated by the emissions from the AGN.