Webb’s Mid-Infrared Instrument, operated by NASA’s Jet Propulsion Laboratory through the launch, also detected jets of gas streaming into space from the binary stars.
Scientists recently got a big surprise from NASA’s James Webb Space Telescope when they turned the observatory toward a group of young stars called WL 20. The region has been studied by at least five telescopes since the 1970s, but it required Webb’s unprecedented resolution and specialized instruments. revealing that what researchers had 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 with Webb’s MIRI (Mid-Infrared Instrument) and was presented at the 244th meeting of the American Astronomical Society on June 12. MIRI also found that the twins have matching jets of gas streaming into space from their north and south poles.
“Our jaws dropped,” said 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 know that these are two stars or that these jets exist. This is really surprising. It’s like having brand new eyes.”
Another surprise for the team was when another observation by the Atacama Large Millimeter/submillimeter Array (ALMA), a group of more than 60 radio antennas in Chile, revealed that both stars were surrounded by disks of dust and gas. Based on the age of the stars, it is possible that planets are forming in these disks.
The combined results suggest that the twins are nearing the end of this early period of their lives, meaning scientists will have an opportunity to learn more about how 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 didn’t see that they were two stars, the ALMA results might look like a single disk with a gap in the middle.” Instead, we have new data on two stars that are apparently at a critical point in their lives when the processes that created them die down.”
WL 20 resides in a much larger, well-studied star-forming region in the Milky Way galaxy called Rho Ophiuchi, a massive cloud of gas and dust about 400 light-years from Earth. In fact, WL 20 is hidden behind dense 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 on Webb, making it well-equipped to peer into obscured star-forming regions like WL 20.
Radio waves can often penetrate dust as well, although they may not reveal the same properties as infrared light. The disks of gas and dust surrounding the two stars in WL 20S emit light in what astronomers call the submillimeter range; these too penetrate the surrounding gas clouds and have been observed by ALMA.
But scientists could have easily interpreted these observations as evidence of a single disk with a gap in it if MIRI hadn’t also observed two starbursts. Gas jets consist of ions, or individual atoms with some electrons removed, that emit at mid-infrared wavelengths but not at submillimeter wavelengths. Only an infrared instrument with spatial and spectral resolution like MIRI could see them.
ALMA can also observe clouds of leftover material from the formation around young stars. These clouds of gas and dust, composed of whole molecules like carbon monoxide, emit light at these longer wavelengths. The absence of these clouds in the ALMA observations indicates that the stars are beyond their initial stage of formation.
“It’s amazing that this region still has so much to teach us about the life cycle of stars,” Ressler said. “I’m excited to see what else Webb reveals.
The James Webb Space Telescope is the world’s leading observatory for space science. Webb solves mysteries in our solar system, looks further to distant worlds around other stars, and explores 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. A division of Caltech in Pasadena, California, JPL led the US MIRI effort, 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