Mystery surrounds NGC 346, one of the most energetic star-forming areas in neighbouring galaxies. With the latest results from NASA’s James Webb Space Telescope, it is now less mysterious.
NCG 346 is in the Small Magellanic Cloud (SMC), a dwarf galaxy in close proximity to the Milky Way. Compared to the Milky Way, the SMC has lower amounts of elements heavier than hydrogen or helium, which astronomers refer to as metals. Since dust grains in space are mostly comprised of metals, scientists anticipated that it would be scarce and difficult to detect. New Webb data indicates the contrary.
This area was examined by astronomers because its circumstances and metal content are similar to those seen in galaxies billions of years ago, at a period in the cosmos known as “cosmic noon,” when star formation was at its zenith. Approximately 2 to 3 billion years after the big bang, galaxies were rapidly generating stars. The explosions of star creation that occurred then continue to influence the galaxies we see today.
“A galaxy at cosmic noon wouldn’t have a single NGC 346 like the Small Magellanic Cloud; it would have dozens” of star-forming areas like this one, said Margaret Meixner, an astronomer from the Universities Space Research Association and the team’s primary investigator. Even though NGC 346 is the sole large star-forming cluster in its galaxy, it provides us with an excellent chance to investigate circumstances that existed at cosmic noon.
By monitoring protostars still in the process of development, scientists may determine if the process of star formation in the SMC differs from what we witness in our own Milky Way. Previous infrared investigations of NGC 346 have concentrated on protostars with masses between 5 and 8 times that of the Sun. Olivia Jones of the United Kingdom Astronomy Technology Centre, Royal Observatory Edinburgh, a co-investigator on the study, stated, “With Webb, we can examine protostars weighing as little as a tenth of the Sun to see whether their formation process is influenced by their reduced metal composition.”
As stars develop, they absorb gas and dust from the surrounding molecular cloud, which appears as ribbons in Webb images. The material accumulates into an accretion disc that nourishes the protostar in the centre. Astronomers had previously identified gas around protostars in NGC 346, but Webb’s near-infrared discoveries indicate the first time that dust has been detected in these discs.
Guido De Marchi of the European Space Agency, a co-investigator on the study team, said, “We are seeing the building blocks, not just of stars, but possibly of planets.” Since the Small Magellanic Cloud has a comparable environment to galaxies around cosmic noon, it’s conceivable that rocky planets might have originated earlier in the universe than scientists previously believed.
The team is also continuing to evaluate spectroscopic data from Webb’s NIRSpec sensor. These data are anticipated to reveal fresh insights into the material accreting onto individual protostars and the protostar’s near surroundings.
These findings were presented during a news conference held on January 11 at the 241st meeting of the American Astronomical Society. The observations were collected as part of the 1227 initiative.
The James Webb Space Telescope is the world’s most sophisticated observatory for space research. It will unearth the mysteries of our solar system, explore distant planets orbiting other stars, and reveal the beginnings of the cosmos and humanity’s position within it. The project is a joint endeavour directed by NASA, with European Space Agency (ESA) and Canadian Space Agency involvement.