That’s no ordinary bathtub ring. Those tiny blue sparkles are young star clusters and bursts of new star formation popping off like slow-mo firecrackers inside the galaxy NGC 3081. Although classified as a spiral galaxy it appears unusual compared to classic spirals because it lacks obvious multiple arms.
NGC 3081 is located more than 86 million light years away in Hydra, a serpentine constellation that snakes beneath Leo and Virgo. You’re seeing the galaxy’s brilliant nuclear region, the center of which harbors a supermassive black hole, encircled by a bright nuclear ring and embedded in a diffuse, yellow-toned ‘bar’ that nearly fills the inside of the outer ring.
The star-studded outer loop is called a resonance ring, a feature that forms in particular locations known as resonances, where gravitational effects within a galaxy cause gas to pile up and accumulate.
In NGC 3081’s case, the big, fat bar of stars is very effective at gathering gas into these resonance regions, causing pile-ups which lead to active and very well-organized star formation. Stars are easily herded and rarely collide, but much larger gas clouds are forced to pile up, collide and collapse, forming brand new star clusters. Gravity may be the most creative force in the universe.
We looked at resonances yesterday where the gravity of a potential ‘Planet X’ shepherds a group of distant asteroids to follow similar orbits. Torques from NGC 8031’s bar as it rotates counterclockwise creates and sustains this beautiful, star-studded ring around the galaxy’s center.