Webb’s mid-infrared instrument, which was managed by NASA’s Jet Propulsion Laboratory until launch, also revealed jets of gas streaming into space from the twin stars.
Scientists recently got a big surprise from NASA’s James Webb Space Telescope when they pointed the observatory at a group of young stars called WL 20. The region has been studied with at least five telescopes since the 1970s, but before that Webb’s unprecedented resolution and specialized instruments were needed. necessary. to reveal that what researchers long thought was one of the stars, WL 20S, is actually a pair that formed about 2 million to 4 million years ago.
The discovery was made using Webb’s Mid-Infrared Instrument (MIRI) and was presented at the 244th meeting of the American Astronomical Society on June 12. MIRI also discovered that the twin matching gas jets flow into space from their north and south poles.
“Our jaws dropped,” says astronomer Mary Barsony, lead author of a new paper describing the results. “After decades of studying this source, we thought we knew it pretty well. But without MIRI we wouldn’t have known these were two stars or that these jets existed. That’s really amazing. It’s like having brand new eyes.”
The team got another surprise when additional observations by the Atacama Large Millimeter/submillimeter Array (ALMA), a group of more than sixty radio antennas in Chile, revealed that disks of dust and gas surround both stars. Based on the age of the stars, it is possible for planets to form in these disks.
The combined results indicate that the twin stars are nearing the end of this early period of their lives, meaning scientists have an opportunity to learn more about how the stars transition from youth to adulthood.
“The power of these two telescopes together is truly incredible,” said Mike Ressler, project scientist for MIRI at NASA’s Jet Propulsion Laboratory and co-author of the new study. “If we hadn’t seen that these were two stars, the ALMA results might have looked like a single disk with a hole in the center. Instead, we have new data about two stars that are clearly at a critical point in their lives, when the processes that created them are disappearing.”
WL 20 is located in a much larger, well-studied star-forming region of the Milky Way galaxy called Rho Ophiuchi, a huge cloud of gas and dust about 400 light-years from Earth. In fact, WL 20 is hidden behind thick clouds of gas and dust that block most of the visible light (wavelengths that the human eye can detect) from the stars there. Webb detects slightly longer wavelengths, called infrared, that can pass through these layers. MIRI detects the longest infrared wavelengths of any instrument at Webb, so it is well equipped to peer into obscured star-forming regions such as WL 20.
Radio waves can often penetrate dust as well, although they may not exhibit the same characteristics as infrared light. The disks of gas and dust surrounding the two stars in WL 20S emit light in a range that astronomers call submillimeters; These also penetrate the surrounding gas clouds and were observed by ALMA.
But scientists could have easily interpreted these observations as evidence of a single disk with a hole in it if MIRI had not also observed the two stellar jets. The gas jets are composed of ions, or individual atoms with some electrons removed, that radiate in mid-infrared wavelengths, but not at submillimeter wavelengths. Only an infrared instrument with spatial and spectral resolution like MIRI’s would be able to see them.
ALMA can also observe clouds of leftover formation material around young stars. These clouds of gas and dust are made up of whole molecules, such as carbon monoxide, and emit light at these longer wavelengths. The absence of these clouds in the ALMA observations shows that the stars have passed their initial formation phase.
“It’s amazing that this region still has so much to teach us about the life cycle of stars,” says Ressler. “I’m excited to see what else Webb will reveal.”
The James Webb Space Telescope is the world’s premier observatory for space science. Webb solves mysteries in our solar system, looks beyond to distant worlds around other stars and investigates the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners ESA (European Space Agency) and CSA (Canadian Space Agency).
MIRI was developed through a 50-50 partnership between NASA and ESA. JPL, a division of Caltech in Pasadena, California, led the U.S. effort for MIRI, and a multinational consortium of European astronomical institutes contributes to ESA. George Rieke of the University of Arizona is the leader of the MIRI science team. Gillian Wright is MIRI’s European Principal Investigator.
Development of the MIRI cryocooler was led and managed by JPL, in collaboration with Northrop Grumman in Redondo Beach, California, and NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
Calla Cofield
Jet Propulsion Laboratory, Pasadena, California.
626-808-2469
calla.e.cofield@jpl.nasa.gov
2024-085