The researchers found this by studying variable stars called Cepheids. They're useful to study, because they brighten and dim periodically, and one can infer their distance based on the length of this cycle. That allows them to be used as distance markers for other objects. A survey using the European Southern Observatory's VISTA telescope — which can cut through the thick dust of the galaxy using infrared — collected images meant to capture these and other variable stars, and the authors of the new study found their bright young things by analyzing several years of the data.
Of the 655 Cepheids they found, they were surprised to note that 35 of them were so-called classical Cepheids — a subtype of young stars.
They were even more surprised when they mapped the young stars and realized that they were forming a disk feature across the center bulge of the Milky Way.
"All of the 35 classical Cepheids discovered are less than 100 million years old. 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," Dante Minniti of the Universidad Andres Bello, the study's second author, said in a statement.
The researchers will continue to study these mysterious young stars to determine their origin.