When you think of astronomers looking at galaxies, you probably imagine far-flung galaxies millions and billions of light-years away. But astronomers also like to take a look closer to home. And they found a surprise near the heart of our galaxy – the Milky Way. A band of unique and very young (astronomically speaking) stars near the center of our galaxy.
Istvan Dékány, who led the team of astronomers, explains how this is different from earlier assumptions. “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!”
Dekany is the lead author of a new study describing the discovery.
The stars are called Cepheids
These type of stars are known for changing very quickly. They expand and contract over a period ranging from just a few days to several months. As they complete each cycle, each star’s brightness sees dramatic changes.
Discovering Cepheids isn’t all that surprising. But, it’s the kind Dekany and his team discovered that is. Cepheids are broken into two primary classes. One of them is much younger than the other. And that’s the one the astronomers discovered – dubbed classical Cepheids. Of the 655 candidate variable stars found during the survey, 35 of them were identified as classical Cepheids.
These 35 stars couldn’t be more different than the type of stars that call the central Milky Way home. Stars found in the central bulge are usually quite old. Another study author, Dante Minniti, talks about how young these stars are.
“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,” said Minniti.
Sounds cool, but what does it mean?
This discovery points to a continuous supply of newly formed stars into the heart of the Milky Way over at least the past 100 million years. Where do they come from? Now that’s a question astronomers really want the answer to. According to the team of astronomers, there are two possibilities. They formed where they sit now, which begs the question – what type of forces are birthing new stars in a region where astronomers thought only old stars reside? Or, they formed somewhere else before ending up where they are today.
The discoveries don’t stop there
While mapping the Cepheids, the team of astronomers also traced a brand new feature in the Milky Way – a thin disc of young stars across the galactic bulge. Until now, this feature remained cloaked behind thick clouds of dust. Thanks to the VISTA telescope, astronomers were able to peer through these dense clouds.
“This part of the galaxy was completely unknown until our VVV survey found it!” adds Minniti.
The 4.1 Meter VISTA Telescope
The Vista Variables in the Vía Láctea Survey (VVV) uses the 4.1 meter VISTA telescope to better understand the structure of our Milky Way Galaxy and how it formed. Check it out below.
VISTA stands for Visible and Infrared Survey Telescope for Astronomy. According to the European Southern Observatory, it’s the world’s largest survey telescope. It looks up into the night sky at near-infrared wavelengths, which helps it pierce thick clouds of gas to reveal what lies behind them.
VISTA’s observations cover everything from small bodies in our solar system to hunting for dark matter and dark energy.
Here are a couple of other images captured during the VVV Survey.
Go to the official VVV Survey page to see more images snapped by the VISTA telescope. Scroll down and look for ‘VVV Image of the Week’ on the right sidebar.