Observations Of The “Cosmic Snake” Lead To Better Understanding Of Star Formation In The Early Universe

The Cosmic Snake. NASA, ESA, M. Postman (STScI) and the CLASH Team

Stars form in dense clumps of gas and dust that we call stellar nurseries. Hubble has seen many stunning examples of these objects in our own and other galaxies. Yet a surprising and unexpected series of observations suggest that stellar nurseries in the early universe packed a lot more material in the same space. But this might not actually be the case.

Thanks to new observations of the “Cosmic Snake”, a French-Swiss collaboration produced a detailed study of stellar nurseries in these distant galaxies. The snake is actually a very distant galaxy, which is serendipitously located behind the core of galaxy cluster MACS J1206.2-084747. The cluster is so massive it distorts and bends light like a lens so that distant galaxy light is amplified and ends up looking like a snake.

“The amplified image is more precise, luminous, and allows us to observe details up to 100 times smaller,” lead author Dr Antonio Cava, from the University of Geneva in Switzerland, said in a statement.

The team studied gas clumps which are about 3,200 light-years across to a detail of roughly 100 light-years. In previous observations, these regions were estimated to contain enough gas to make over 3 billion stars like our Sun but the new study, published in Nature Astronomy, shows that most of them are smaller than that, with the average clump weighing around 100 million times the mass of the Sun. This is broadly consistent with the simulations.

The team highlighted how the apparently giant clumps are either smaller than previously thought or appear as one despite being made by smaller (unresolved) components. These observations wouldn’t have been possible without gravitational lensing.

The cosmic snake. NASA, ESA, Cava et al.

“We have reduced the differences between what we observe in the nearby universe and in distant galaxies from a factor 1,000 to a factor 10,” explained Professor Daniel Schaerer from the Geneva Observatory.

The research is a serious advancement in understanding star formation in the early universe. We have estimated that star formation in galaxies peaked around 3.5 billion years after the Big Bang. The Cosmic Snake is producing 30 times more stars than the Milky Way and there are galaxies making 100 if not 1,000 times more stars than our own.


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