New York: A team of astronomers has discovered a previously unknown component of our home galaxy, the Milky Way — a thin disc of young stars in the central region of the galaxy buried behind thick clouds of dust.
The centre of the Milky Way galaxy, a region previously thought to consist of vast numbers of old stars, actually has young stars, the study showed.
To make the discovery, the researchers used data from VISTA telescope at European Southern Observatory’s Paranal Observatory in Chile, taken between 2010 and 2014.
“The central bulge of the Milky Way is thought to consist of vast numbers of old stars. But the VISTA data has revealed something new — and very young by astronomical standards,” said lead author of the new study Istvan Dekany from Pontifical Catholic University of Chile.
The astronomers found 655 candidate variable stars of a type called Cepheids. These stars expand and contract periodically, taking anything from a few days to months to complete a cycle and changing significantly in brightness as they do so.
The researchers found that Cepheids are not all the same — they come in two main classes, one much younger than the other.
Out of their sample of 655, the team identified 35 stars as belonging to a sub-group called classical Cepheids — young bright stars, very different from the usual, much more elderly, residents of the central 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,” second author of the study Dante Minniti from Universidad Andres Bello, Santiago, Chile, noted.
The ages of these classical Cepheids provide solid evidence that there has been a previously unconfirmed, continuous supply of newly formed stars into the central region of the Milky Way over the last 100 million years.
Mapping the Cepheids, the team also traced an entirely new feature in the Milky Way — a thin disc of young stars across the galactic bulge.
This new component to our home galaxy had remained unknown and invisible to previous surveys as it was buried behind thick clouds of dust, the researchers said.
The findings appeared in Astrophysical Journal Letters.