Webb reveals star formation in cluster dust lanes

Jan. 13 () –

The Webb Space Telescope has revealed star formation in the dust lanes of the cluster NGC 346, in the Small Magellanic Cloud, a dwarf galaxy close to our Milky Way.

SMC contains lower concentrations of elements heavier than hydrogen or helium, which astronomers call metals, compared to the Milky Way. Since dust grains in space are mostly made of metals, scientists expected small amounts of dust to be present and difficult to detect. New Webb data reveals otherwise.

Astronomers explored this region because the conditions and amount of metals within the Small Magellanic Cloud resemble those observed in galaxies that existed billions of years ago, during an era of the universe known as the “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 dizzying rate. The fireworks of star formation that occurred then still shape the galaxies we see around us today.

“A galaxy during cosmic noon would not have one NGC 346 region like the Small Magellanic Cloud; it would have thousands of star-forming regions like this,” he said. it’s a statement Margaret Meixner, an astronomer with the Association of Universities for Space Research and principal investigator on the team for this study. “But even if NGC 346 is now the only furiously star-forming massive cluster in its galaxy, offers us a great opportunity to investigate the conditions that existed at cosmic noon“.

By looking at protostars that are still in the process of forming, researchers can tell if the star formation process in the SMC is different from what we observe in our own Milky Way. Previous infrared studies of NGC 346 have focused on protostars heavier than five to eight times the mass of our Sun. “With Webb, we can investigate lighter-weight protostars, as small as a tenth of our Sun, to see if their formation process is affected by the lower metal content,” said Olivia Jones of the UK Center for Astronomical Technology at the Royal Observatory in Edinburgh, a co-investigator on the programme.

As stars form, they accumulate gas and dust, which can be seen as fringes in Webb’s images, coming from the surrounding molecular cloud. The material accumulates in an accretion disk that feeds the central protostar. Astronomers have detected gas around the protostars that are inside NGC 346, but Webb’s near-infrared observations mark the first time that dust has also been detected on these disks.

“We’re looking at the building blocks, not just of stars, but also potentially of planets,” said Guido De Marchi of the European Space Agency and a co-investigator on the study team. “And since the Small Magellanic Cloud has an environment similar to that of galaxies during cosmic noon, rocky planets may have formed in the universe earlier than we thought.”

The team also has spectroscopic observations from Webb’s NIRSpec instrument that they continue to analyze. These data are expected to provide new insights into the material that accumulates on individual protostars, as well as the immediate environment surrounding protostars.