Free Astronomy Magazine March-April 2023

16 MARCH-APRIL 2023 ASTRO PUBLISHING one NGC 346 like the Small Magel- lanic Cloud does; it would have thou- sands 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 condi- tions that were in place at cosmic noon.” By observing protostars still in the process of forming, re- searchers can learn if the star forma- tion process in the SMC is different from what we observe in our own Milky Way. Previous infrared studies of NGC 346 have focused on proto- stars heavier than about 5 to 8 times the mass of our Sun. “With Webb, we can probe down to lighter- weight protostars, as small as one tenth of our Sun, to see if their for- mation process is affected by the lower metal content,” said Olivia Jones of the United Kingdom As- tronomy Technology Centre, Royal Observatory Edinburgh, a co-investi- gator on the program. As stars form, they gather gas and dust, which can look like ribbons in Webb imagery, from the surround- ing molecular cloud. The material collects into an accretion disk that feeds the central protostar. As- tronomers have detected gas around protostars within NGC 346, but Webb’s near-infrared observations mark the first time they have also de- tected dust in these disks. “We’re seeing the building blocks, not only of stars, but also potentially of planets,” said Guido De Marchi of the European Space Agency, a co-in- vestigator on the research team. “And since the Small Magellanic Cloud has a similar environment to galaxies during cosmic noon, it’s pos- sible that rocky planets could have formed earlier in the universe than we might have thought.” The team also has spectroscopic observations from Webb’s NIRSpec instrument that they are continuing to analyze. These data are expected to provide new insights into the material accret- ing onto individual protostars, as well as the environment immedi- ately surrounding the protostar. N GC 346, one of the most dy- namic star-forming regions in nearby galaxies, is full of mys- tery. Now, it is less mysterious with new findings from NASA’s James Webb Space Telescope. NCG 346 is located in the Small Magellanic Cloud (SMC), a dwarf galaxy close to our Milky Way. The SMC contains lower concentrations of elements heavier than hydrogen or helium, which astronomers call metals, com- pared to the Milky Way. Since dust grains in space are composed mostly of metals, scientists expected there would be low amounts of dust, and that it would be hard to detect. New data from Webb reveals the oppo- site. 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 uni- verse 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 hap- pening then still shape the galaxies we see around us today. “A galaxy during cosmic noon wouldn’t have Star forming region NGC 346 seen by Webb by NASA/ESA/CSA Matthew Brown Christine Pulliam N GC 346, shown here in this image from NASA’s James Webb Space Telescope Near-Infrared Camera (NIRCam), is a dynamic star cluster that lies within a nebula 200,000 light years away. Webb reveals the presence of many more building blocks than previously expected, not only for stars, but also planets, in the form of clouds packed with dust and hydrogen. The plumes and arcs of gas in this image contains two types of hydrogen. The pink gas represents energized hydrogen, which is typically as hot as around 10,000 °C (approximately 18,000 °F) or more, while the more orange gas represents dense, molecular hydrogen, which is much colder at around -200 °C (approximately -300 °F) or less, and asso- ciated dust. [NASA, ESA, CSA, Olivia C. Jones (UK ATC), Guido De Marchi (ESTEC), Margaret Meixner (USRA). Image processing: Alyssa Pagan (STScI), Nolan Habel (USRA), Laura Lenki ć (USRA), Laurie E. U. Chu (NASA Ames)] !