A recent study published in the journal Science by an international team of space scientists has revealed that the observation of a gas cloud stream heading towards a massive galaxy could provide evidence of gas material recycling. The scientists have predicted for years that enriched gases surrounding galaxies could be pulled into the galaxies, contributing to the formation of new stars. They suggest that such gases may have come to exist due to supernova explosions that escape their galaxy, and when these gases are pulled back into a galaxy, they undergo recycling.
The research team analyzed data from the Subaru and Keck II telescopes, focusing on a massive galaxy at redshift 2.3, surrounded by a nebula called MAMMOTH-1. When the nebula was first discovered in 2017, it was considered mysterious. However, the scientists’ new examination suggests that the galaxy is pulling material from the nebula closer, via three distinct gas streams. They found that two of the streams pointed to a single quasar that they believe lives in the galaxy.
Further analysis of the streams showed that, in addition to hydrogen and helium, they also contain a lot of carbon, which prior research has shown is created inside stars. Therefore, the carbon in the gas stream must have once existed in a star, but now no longer does, hinting at its expulsion due to a supernova. The fact that the gas in which the carbon exists is part of a stream heading towards the galaxy suggests that it will soon be used to contribute to the formation of new stars.
The team’s kinematic modeling of the galaxy and nebula showed the gas streams spiraling into the galaxy, indicating that they are likely part of a massive recycling process in which stars explode, and leftover material from the explosions winds up as material used for the construction of new stars. This new evidence supports the long-standing prediction of gas material recycling in the universe.