Only a few hundred light-years from the center of the Milky Way lies an enormous cloud of gas and cosmic dust coalescing to form new baby stars.
Astronomers want to know why it’s so fertile, especially when compared to the neighborhood. Despite having just 10 percent of the central region’s star-making gas, the cloud, known as Sagittarius B2, accounts for half of all the area’s stellar births, according to NASA.
Getting to the bottom of that mystery may also give scientists new insights into the star-forming process as a whole. Stars create most of the chemical elements on Earth, including carbon and oxygen, which are essential for life. But even experts admit they have much to learn about the conditions necessary in space to create new stars.
To study this mysterious nursery, scientists pointed the James Webb Space Telescope at it. The observations resulted in stunning new images of the galaxy’s most massive star-forming cloud, just a short distance from Sagittarius A*, the supermassive black hole that defines the center.
“Webb’s powerful infrared instruments provide detail we’ve never been able to see before, which will help us to understand some of the still-elusive mysteries of massive star formation and why Sagittarius B2 is so much more active than the rest of the galactic center,” said Adam Ginsburg, one of the principal investigators, in a statement.
In April, a team of astronomers used Webb to look closer at Sagittarius C, another nearby cloud, but one with relatively few babies, to chisel away at the same question: If there’s a lot of available star-forming ingredients in this region, why aren’t there more newborn stars? Researchers now believe powerful magnetic fields may have something to do with it — perhaps countering star formation.
Webb was specifically designed to sense invisible light at stretched-out infrared wavelengths. In short, light stretches — or “redshifts” — over time and distance by the expansion of the universe. Those infrared waves can also pierce through the prevalent gas and dust in space that obscure the view of far and naturally dim light sources.
MID-INFRARED
In mid-infrared light, Sagittarius B2 only reveals its brightest stars. The dark areas are not empty space but filled with such dense gas and dust that light is blocked from reaching the telescope.
Credit: NASA / ESA / CSA / STScI / Adam Ginsburg / Nazar Budaiev / Taehwa Yoo / Alyssa Pagan
NEAR-INFRARED
In near-infrared light, the diverse colors of stars in Sagittarius B2 are on full display, but less of its gas and dust shine through than can be seen in mid-infrared light.
Credit: NASA / ESA / CSA / STScI / Adam Ginsburg / Nazar Budaiev / Taehwa Yoo / Alyssa Pagan
Infrared light passes through some of the region’s thick clouds, allowing Webb to detect young stars and the warm dust around them. But one of the most intriguing aspects of the new study is what Webb still couldn’t see. There are areas in the new images that appear dark. Scientists say they’re not what they seem.
“These ironically empty-looking areas of space are actually so dense with gas and dust that even Webb cannot see through them,” according to NASA. “These thick clouds are the raw material of future stars and a cocoon for those still too young to shine.”
Researchers plan to do follow-up studies on the stars in Sagittarius B2 to learn more about their masses and ages. That information could help them understand how long the star-forming cloud has existed. Right now they can’t say whether it’s been going on for millions of years or an unknown process initiated it more recently.
“Humans have been studying the stars for thousands of years, and there is still a lot to understand,” said Nazar Budaiev, the other principal investigator, in a statement. “For everything new Webb is showing us, there are also new mysteries to explore, and it’s exciting to be a part of that ongoing discovery.”