Hubble Spots NGC 1266 Exactly as Its Stars Stop Forming

Sharp detail from NASA’s Hubble Space Telescope brings every feature of NGC 1266 into clear view. Dust lanes in shades of reddish brown stretch across the galaxy’s flattened disk and weave around a bright central bulge. Hints of spiral structure linger in the disk even though no obvious arms stand out. Tiny clumps and filaments of dust partly hide the core while distant background galaxies shine through the outer haze in red, blue, and orange tones against the black of space.

This intriguing galaxy, situated in the constellation Eridanus, is classed as a Lenticular type, a subset of graceful spirals and rounded ellipticals. This is a one-percent unusual post-starburst galaxy because, some 500 million years ago, something extraordinary occurred that activated the galaxy’s star formation switch for a brief period of time before turning it off.

A minor collision with another galaxy set the entire event into action. Fresh gas began to rush into the center, causing rapid star formation and bulge growth, while the supermassive black hole at the galaxy’s heart re-emerged as an active galactic nucleus. As a result, a strong energy jet shot out of the black hole, sending winds and jets flying out. These eruptions then swept up gas and churned up all of the space between the stars, stopping fresh star formation in the process.

Hubble and other instruments have allowed us to confirm this. These days, you can still see streams of gas rushing out from the core, and star-forming nurseries are only found in the very center, while the remainder of the galaxy sleeps soundly. The star formation rate is a mere 0.87 solar masses per year, which is a fraction of what one would anticipate from a galaxy of this size, and as a result, the molecular clouds never have a chance to settle long enough to collapse.

The visible black hole activity is responsible for the outflow of gas. The same jets that caused the initial starburst a few hundred million years ago are now keeping new stars from forming. Gas departs the galaxy at a pace of approximately 110 solar masses every year, albeit the majority of it remains trapped rather than departing. This cause-and-effect cycle exemplifies how enormous core black holes can influence the evolution of their host galaxy.