Located about 200 light-years away from the Small Magellanic Cloud (SMC), NCG 346 is one of the most dynamic star-forming regions in nearby galaxies. The massive star cluster NGC 346 has long intrigued astronomers. Now NASA’s James Webb Space Telescope is revealing the mystery of its star formation.
Compared to the Milky Way, the SMC has lower amounts of metals, elements heavier than hydrogen or helium. Scientists expected that there would be little dust and that it would be challenging to identify them because most of the dust particles in space are made of metal. Webb’s most recent data shows the opposite.
Margaret Meixner, an astronomer with the Universities Space Research Association and principal investigator on the research team, said: “A galaxy during cosmic noon would not have one NGC 346 like the Small Magellanic Cloud; it would have thousands. But even if NGC 346 is now the only massive cluster furiously forming stars in its galaxy, it presents us with a great opportunity to examine cosmic noon conditions.”
Scientists can determine whether the star formation process in the SMC differs from what we see in our Milky Way by looking at protostars that are still forming. Protostars with masses greater than 5 to 8 times that of the Sun have been the main subject of previous infrared observations of NGC 346.
Olivia Jones of the United Kingdom Astronomy Technology Centre, Royal Observatory Edinburgh, a co-investigator on the programme, said: “With Webb, we can target lighter protostars, as small as a tenth of our sun, to see if their formation process is affected by the lower metal content.”
In Webb’s images, dust and gas from the surrounding molecular cloud can form ribbons as stars form and gather. An accretion disk receives the material and feeds the protostar at its core. Within NGC 346, astronomers have discovered gas around protostars, but Webb’s near-infrared surveys are the first to reveal dust in these disks.
Guido De Marchi of the European Space Agency, a co-investigator of the research team, said: “We see the building blocks, not only of stars, but possibly also of planets. And since the Small Magellanic Cloud has a similar environment to galaxies during cosmic noon, it’s possible that rocky planets formed earlier in the universe than we might have thought.”
The team also has spectroscopic observations from Webb’s NIRSpec instrument that they continue to analyze. This data is expected to provide new insights into the material accreting on individual protostars and the environment immediately surrounding the protostar.
These results will be presented Jan. 11 at a press conference at the 241st meeting of the American Astronomical Society. The observations were obtained as part of program 1227.