The James Webb Space Telescope (JWST) is a large, infrared-optimized space telescope developed by NASA, with significant contributions from the European Space Agency (ESA) and the Canadian Space Agency (CSA). The telescope is designed to study the early universe, the formation of galaxies, and the evolution of stars and planetary systems. JWST has the capability to study the dust and gas clouds where stars are forming, and has recently uncovered new insights into the process of star formation in clusters of stars by observing the dust ribbons within these clusters. The telescope has been able to see through the dust to observe the youngest, most embedded stars that are still forming.
NGC 346, one of the most dynamic star-forming regions in nearby galaxies, is shrouded in mystery. It is now less mysterious thanks to new findings from NASA’s James Webb Space Telescope. NCG 346 is located in the Small Magellanic Cloud (SMC), a dwarf galaxy near our Milky Way. In comparison to the Milky Way, the SMC has lower concentrations of elements heavier than hydrogen or helium, known as metals. Because dust grains in space are mostly composed of metals, scientists predicted that there would be little dust and that it would be difficult to detect. Webb data shows the opposite.
Astronomers probed this region because the conditions and amount of metals within the SMC resemble those seen in galaxies billions of years ago, during an era in the universe known as “cosmic noon,” when star formation was at its peak. Some 2 to 3 billion years after the big bang, galaxies were forming stars at a furious rate. The fireworks of star formation happening then still shape the galaxies we see around us today.
We’re seeing the building blocks not only of stars, but potentially of planets. And, because the Small Magellanic Cloud has a similar environment to galaxies during cosmic noon, rocky planets may have formed earlier in the universe than we previously thought.
Guido De Marchi
“A galaxy during cosmic noon wouldn’t have one NGC 346 like the Small Magellanic Cloud does; it would have thousands” of star-forming regions like this one, said Margaret Meixner, an astronomer at the Universities Space Research Association and principal investigator of the research team. “But even if NGC 346 is now the one and only massive cluster furiously forming stars in its galaxy, it offers us a great opportunity to probe conditions that were in place at cosmic noon.”
Researchers can learn if the star formation process in the SMC differs from what we see in our own Milky Way by observing protostars that are still in the process of forming. Previous infrared studies of NGC 346 concentrated on protostars weighing 5 to 8 times the mass of our Sun. “With Webb, we can probe down to lighter-weight protostars, as small as one-tenth the size of our Sun, to see if their formation process is affected by the lower metal content,” said Olivia Jones, a co-investigator on the program at the United Kingdom Astronomy Technology Centre, Royal Observatory Edinburgh.
As stars form, they gather gas and dust, which can look like ribbons in Webb imagery, from the surrounding molecular cloud. The material collects into an accretion disk that feeds the central protostar. Astronomers have detected gas around protostars within NGC 346, but Webb’s near-infrared observations mark the first time they have also detected dust in these disks.
“We’re seeing the building blocks not only of stars, but potentially of planets,” said Guido De Marchi, a co-investigator on the research team at the European Space Agency. “And, because the Small Magellanic Cloud has a similar environment to galaxies during cosmic noon, rocky planets may have formed earlier in the universe than we previously thought.”
The team is also continuing to analyze spectroscopic observations from Webb’s NIRSpec instrument. These findings are expected to shed new light on the material accreting onto individual protostars, as well as the environment around the protostar. These findings will be presented at a press conference at the American Astronomical Society’s 241st meeting. The observations were obtained as part of program 1227.
