Saturday, March 17, 2018

'Red and dead' NGC 1277 offers insights on the early universe

New analysis of a "relic galaxy" promises insights into the nature of the early universe. Formed some 12 billion years ago, the NGC 1277 galaxy birthed all of its stars within a span of 100 million years -- a star formation rate 1,000 times greater than that of the Milky Way. But nearly as quickly as the galaxy sprang to life, it died out. For the last 10 billion years, NGC 1277 has remained unchanged -- a relic of an earlier time in galactic evolution. To better understand the dynamics of the early universe, scientists used the Hubble Space Telescope to study NGC 1277. The lenticular galaxy is what's known as a "red and dead" galaxy. Most dead and red galaxies are found in the distant universe, too far away to be imaged in great detail. But at 240 million light-years away from Earth, NGC 1277 is close enough to offer insights. Most galaxies feature both red globular clusters, full of metal-rich stars, and blue clusters, globs of metal-poor stars. Models of galactic evolution suggest red clusters form during the earliest stages of a galaxy's formation, with blue clusters acquired later as new star forming material is pulled from the galaxy's surroundings. The lack of blue globular clusters is a sign that a galaxy stopped evolving -- that it is in a "state of arrested development."

Red and dead galaxies host mostly red clusters. NGC 1277 has only red clusters.

"I've been studying globular clusters in galaxies for a long time, and this is the first time I've ever seen this," Michael Beasley, a researcher with the Astrophysics Institute of the Canary Islands, said in a news release.

Scientists believe the massive black hole at the center of NGC 1277 grew quickly, pulling in stellar materials at a prodigious rate, inspiring the formation of the galaxy. But it's development stopped suddenly when it ran out of stellar material. As a result, the galaxy hosts a massive stellar popular but is extremely compact.

NGC 1277 is surrounded by other galaxies from which it could steal new material, but the latest Hubble findings show it is moving too fast to merge with other galaxies or acquire significant amounts of debris.

Described this week in the journal Nature, NGC 1277 is just one of 50 dense, compact relic galaxies identified by the Sloan Digital Sky Survey. Scientists hope future surveys of similar candidates will help astronomers better understand the nuances of galactic evolution in the early universe.

Scientists also hope newer, more powerful telescopes will help them study the role of dark matter in the formation and evolution of oddball galaxies like NGC 1277.

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