The sparkling scene depicted in this week’s Hubble Picture of the Week is of the spiral galaxy NGC 5248, located 42 million light-years from Earth in the constellation Boötes. It is also known as Caldwell 45, having been included in a catalogue of visually interesting celestial objects that were known, but weren’t as commonly observed by amateur astronomers as the more famous Messier objects.

NGC 5248 is one of the so-called ‘grand design’ spirals, with prominent spiral arms that reach from near the core out through the disc. It also has a faint bar structure in the centre, between the inner ends of the spiral arms, which is not quite so obvious in this visible-light portrait from Hubble. Features like these which break the rotational symmetry of a galaxy have a huge influence on how matter moves through it, and eventually its evolution through time. They feed gas from a galaxy’s outer reaches to inner star-forming regions, and even to a galaxy’s central black hole where it can kick-start an active galactic nucleus.

These flows of gas have shaped NGC 5248 in a big way; it has many bright ‘starburst regions’ of intense star formation spread across its disc, and it is dominated by a population of young stars. The galaxy even has two very active, ring-shaped starburst regions around its nucleus, filled with young clusters of stars. These ‘nuclear rings’ are remarkable enough, but normally a nuclear ring tends to block gas from getting further into the core of a galaxy. NGC 5248 having a second ring inside the first is a marker of just how forceful its flows of matter and energy are! Its relatively nearby, highly visible starburst regions make the galaxy a target for professional and amateur astronomers alike.