Two cosmic discoveries made in part by UCSB researchers are teaching scientists more about the formation of stars and galaxies.
Matteo Cantiello of the Kavli Institute for Theoretical Physics was part of an international team studying a newly observed massive star with unique behavior and record-breaking characteristics. The star was discovered during the researchers’ observation of roughly a thousand stars in the Large Magellanic Cloud, a satellite of the Milky Way galaxy in which new stars are formed.
The discovery comes just a few years after Cantiello published a paper in 2007 speculating about the existence of such astronomical bodies.
The star — large enough to fit a thousand stars the size of our sun inside it — is rotating at about six hundred kilometers per second, faster than any other star ever discovered. By comparison, our sun rotates no faster than two kilometers per second, according to Cantiello.
“This velocity is so high that basically every object is moving so fast that it’s loosely bound to the star,” Cantiello said.
The rotational speed is enough for materials on the star’s surface to reach escape velocity, meaning the star likely has a halo of materials surrounding it that have been flung from its surface. In addition to the rotational speed, the star is unique in that it seems to be moving away from the stars around it.
“The two things are suspiciously peculiar and we think they’re correlated,” Canitello said.
Canitello said the team was able to deduce this by measuring the wavelength of light given off by the star.
Another UCSB researcher, Tommaso Treu, was involved in the discovery of the most distant protocluster of newly forming galaxies ever seen, 13.1 billion light years away and composed of five protogalaxies.
The protocluster was found using the Hubble telescope and is helping scientists understand the formation of structures in the early history of the universe. Treu said the discovery reveals a wealth of information about the formation of galaxies.
“It tells us that groups of galaxies are already in place a mere 600 million years after the Big Bang and that the universe is already almost completely ionized by this time,” Treu said in an email. “At the time when the light that left these galaxies was emitted, galaxies were much smaller, more irregular in shape and more actively star-forming than present day galaxies.”
The discovery represents the oldest galactic structures observable and thus the furthest look back into the history of galaxies in the universe. It was made possible by recent modifications to the Hubble telescope, Treu said.
“We used the infrared camera Wide Field Camera 3 on board the Hubble Space Telescope,” Treu said. “This camera was installed in 2009 and revolutionized the way we can study the very distant [and] early universe.”