Deep in the heart of the Milky Way lies a bustling region near to the galaxy’s supermassive black hole, where stars are born. But something strange is happening there: the rate of star formation is lower than it seems like it should be. With thick clouds of dust and gas, the Sagittarius C region should be bursting with new baby stars, but instead there are relatively few new stars formed there. And now, research using the James Webb Space Telescope is revealing why.
Webb first observed the region called Sagittarius C in 2023. Now researchers are now using those observations to study star formation in the wider area around the center of the Milky Way, known as the Central Molecular Zone.
“A big question in the Central Molecular Zone of our galaxy has been, if there is so much dense gas and cosmic dust here, and we know that stars form in such clouds, why are so few stars born here?” said researcher John Bally of the University of Colorado Boulder. “Now, for the first time, we are seeing directly that strong magnetic fields may play an important role in suppressing star formation, even at small scales.”
The forces at play in the region are captured in the image above, which uses data from a radio telescope called MeerKAT and shows filaments of hot gas that are shaped by magnetic fields. In the image, you can see the supermassive black hole known as Sagittarius A* as the bright yellow blob at the very center. This enormous monster with a mass four million times that of the sun feeds on dust and gas which swirl around it, and as the material swirls it heats up due to friction and glows — making it visible even though the black hole itself swallows all light.
All of this mass creates magnetic fields which are amplified by the movements of gas swirling around the black hole, and these fields are shaping the gas in the region and preventing it from spreading out. The reason that few stars are being born seems to be that the magnetic fields act against the gravitational forces which collapse clouds of dust and gas to form new stars.
“We were definitely not expecting those filaments,” said fellow researcher Rubén Fedriani of the Instituto de Astrofísica de Andalucía in Spain. “It was a completely serendipitous discovery.”
The research is published in The Astrophysical Journal.
