A group of young stars has been detected near the middle of our Milky Way galaxy, hanging out in an "older" neighborhood previously assumed to be dominated by a mature population of stars, researchers say.
The central bulge of our galaxy was always thought to be the home of mostly ancient stars, and the region was believed to have used up all of its star-making resources long ago.
However, the bulge is apparently still creating stars, researchers report in Astrophysical Journal Letters.
They studied several years of data collected by the European Southern Observatory's Vista telescope in Chile, which peered into the dust-obscured center of our galaxy from 2010 to 2014.
They focused on a class of variable stars known as Cepheids, which periodically brighten and then dim. The period of that variability provides a handy "yardstick" to measure how far away they are.
However, out of 655 Cepheids observed in the center of our galaxy, 35 were of a type known as classical Cepheids — a subtype of the class that are young stars, much younger than the older stars making up most of the residents of the central bulge.
Mapping those young stars showed they were arranged in a disk right across the center of the Milky Way, the researchers say.
It had previously gone undetected within the thick clouds of dust there, only revealed by Vista's ability to use high-resolution, wide-field imaging at infrared wavelengths to study structures deep within the Milky Way.
"All of the 35 classical Cepheids discovered are less than 100 million years old," says researcher Dante Minniti of the Universidad Andres Bello in Santiago, Chile. "The youngest Cepheid may even be only around 25 million years old, although we cannot exclude the possible presence of even younger and brighter Cepheids."
The finding is strong evidence of a previously-undetected, ongoing creation of newly-formed stars in the center of our galaxy for the last 100 millions years, the researchers say.
Further research will be needed to determine whether these younger Cepheid stars were born close to where they've been observed or whether they originated somewhere else and have subsequently migrated toward the galactic center, the researchers say.
Vista will be the perfect tool for such work, the scientists say.
"This study is a powerful demonstration of the unmatched capabilities of the Vista telescope for probing extremely obscured galactic regions that cannot be reached by any other current or planned surveys," says Istvan Dékány of the Pontificia Universidad Católica de Chile.
