The early Universe was a very different place from our own, and astronomers don’t fully understand how baby stars grew up in this environment. And while instruments like the James Webb Space Telescope will probe to the earliest epochs of star formation, we don’t always have to try so hard — maybe there are more clues.
Star formation is a complex matter. To make a baby star, you must start with a large, amorphous, blob-like cloud of gas and dust and compress it to the density needed to trigger nuclear fusion. For this process to work, a lot of heat must also be dissipated. This is because the gas cloud heats up as it is compressed, and a hot gas cloud can stay in equilibrium forever. So when the gas cloud is being compressed, you also have to extract heat from the system to allow it to be compressed even more.
Modern gas clouds do this by emitting radiation as they compress, and elements heavier than helium (they’re commonly referred to as metals in the astronomy world) do a fantastic job of removing heat from the collapsing gas clouds. But in the early Universe, these gas clouds were much more pristine, containing little to no metals.
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Astronomers don’t yet understand how stars formed in such a metal-poor environment.
One way to address this problem is to use giant observatories like the James Webb Space Telescope. Another option, spearheaded by Professor Toshikazu Onishi of Osaka Metropolitan University and Project Assistant Professor Kazuki Tokuda of Kyushu University, is to look around nearby. Like the Small Magellanic Cloud.
(Left): Far-field, far-infrared image of the Small Magellanic Cloud taken by the Herschel Space Observatory. (Right): An image of the molecular outflow of baby star Y246. Cyan and red show the blue-shifted and red-shifted gas observed in carbon monoxide emission. The cross indicates the position of the baby star. Image credit: ALMA (ESO/NAOJ/NRAO), Tokuda et al. ESA/Herschel
The Small Magellanic Cloud isn’t quite as pristine as the early Universe, but it contains far fewer metals than the average in the Milky Way. And as an added bonus, it’s much more accessible to us than the early universe.
The international team of astronomers recently used ALMA, the Atacama Large Millimeter/submillimeter Array, and captured a baby star in the process of formation. They observed extremely rapid outflows from the newborn star. These outflows are driven by incredibly strong electric and magnetic fields in the gas cloud as it is being compressed.
Astronomers believe such outflows suppress the rotational motion of gas around the newly forming star. This slowdown increases the growth rate, potentially leading to larger stars. Further research will show if this is a common star-building method in the early Universe, potentially resulting in stars much larger than today’s average.