Hubble Sights Galaxy in Transition
3 min read
Hubble Sights Galaxy in Transition
This NASA Hubble Space Telescope image reveals an enigmatic galaxy with a bright center and a face that hints at spiral structure, yet it holds no obvious spiral arms. Reddish-brown clumps and filaments of dust partially obscure the galaxy’s full face, while red, blue, and orange light from distant galaxies shines through its diffuse outer regions and dots the inky-black background.
NGC 1266 is a lenticular galaxy located some 100 million light-years away in the constellation Eridanus (the Celestial River). Astronomers classify lenticulars as transitional galaxies that represent an evolutionary bridge between spirals and ellipticals. Lenticulars are “lens-shaped” and have a bright central bulge and flattened disk like spirals, but they have no spiral arms and little to no star formation like ellipticals.
As interesting as this galaxy’s structure and lenticular classification are, those traits aren’t its most intriguing features. NGC 1266 is a rare post-starburst galaxy that is in transition between a galaxy that experienced a major burst of star formation and a quieter elliptical galaxy. Post-starburst galaxies have a young population of stars but few star-forming regions. Roughly one percent of the local galaxy population is a post-starburst galaxy.
Astronomers think that NGC 1266 had a minor merger with another galaxy some 500 million years ago. The merger spurred the formation of new stars and increased the mass of the galaxy’s central bulge while funneling gas into its supermassive black hole. The additional matter made the black hole much more active, creating an active galactic nucleus or AGN. The black hole’s increased activity would have generated powerful winds and jets of gas along its axis of rotation. Over time, the burst of new stars and the black hole’s powerful jets would deplete the galaxy’s reservoir of star-forming gas, while the turbulence generated in these processes suppressed new stars from forming in the gas that remained.
Observations by Hubble and other observatories reveal a strong outflow of gas from the galaxy and that the space between its stars is shocked or highly disturbed. Researchers found that any remaining stellar nurseries are in the core of the galaxy, and that very little to no star formation happens beyond that core. These observations suggest the supermassive black hole in the galaxy’s heart may be suppressing star birth by stripping or ejecting star-forming gas from the galaxy. The shockwaves from this process would create turbulence that disturbs the gas and dust between stars enough to stop any remaining matter from gravitationally condensing into infant stars.
Post-starburst galaxies like NGC 1266 are ideal subjects for astronomers to study the complex physical processes that suppress star formation. They help us better understand the evolution of galaxies and how supermassive black holes interact with their hosts.
Media Contact:
Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, MD
claire.andreoli@nasa.gov
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