Everyone on Earth is used to recycling, but no one imagined that this could happen in space. An international team of scientists led by astronomers Shiwu Zhang and Zheng Cai from Tsinghua University in China have found evidence that a huge galaxy inside an even larger nebula called MAMMOTH-1 is collecting material from the space around it to give birth to new stars.
The material in the nebula contains elements from supernova explosions thought to have originated within galaxies. This means that the galaxy, which the research team calls G-2, is currently forming stars from material that was previously ejected into intergalactic space, either by the galaxy itself or by another nearby one. “The simulations have shown that gas recycling — the re-formation of gas that was previously ejected from the galaxy — can support star formation in the early universe,” according to a study published last month in the journal Science.
The MAMMOTH-1 nebula contains abundant raw materials for star formation, and observations from the Subaru and Keck II telescopes have shown that three gaseous streams flow from the nebula into one of the galaxies inside it. MAMMOTH-1 is a particularly huge nebula that lives up to its name. The outflows of gas from this nebula span an astonishing 100 kiloparsecs (325,000 light years). These streams can provide any galaxy with everything necessary for the birth of a new generation of stars.
The research team created kinematic models of galaxies and nebulae to see exactly how the gaseous streams move. It turned out that the streams are spiraling into the galaxy, which, in their opinion, is another proof of the presence of a huge amount of material that can be processed into new stars. Observations with the Subaru and Keck II telescopes showed that these streams glowed with emission lines indicating the presence of hydrogen and helium, which was to be expected. But they also contained significant amounts of carbon. The presence of carbon indicates that the cloud contains heavier elements that most likely originated from long-dead stars.
The observation of MAMMOTH-1 revealed something else: the two streams of gas heading towards the galaxy that attracts them come from the same quasar. Quasars form when the supermassive black holes at the center of galaxies absorb enough material to emit plumes of matter and radioactive radiation. These jets can eject material from the entire galaxy.
The researchers determined that this quasar is most likely not located in the same galaxy that is attracting material. Thus, it seems that this is the case when one galaxy recycles material thrown out by another.
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