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Mystery gas shooting out of the center of Milky Way ‘like bullets’

Astronomers have stumbled across a mystery at the heart of the Milky Way: A dense, cold gas shooting out of the region “like bullets.”

Researchers aren’t sure what the source of the gas is or how it’s being propelled so fast. They have previously observed flows of hot gas, but not cold gas which is harder to move due to it being heavier. The flow of cold gas could possibly be due to the supermassive black hole in the area or perhaps due to cosmic winds related to star formation.

“This is the first time something like this has been observed in our galaxy,” lead author Dr. Enrico Di Teodoro from Johns Hopkins University said in a statement. “We see these kind of processes happening in other galaxies. But, with external galaxies you get much more massive black holes, star formation activity is higher, it makes it easier for the galaxy to expel material. And these other galaxies are obviously a long way away, we can’t see them in a lot of detail.

“Our own galaxy is almost like a laboratory that we can actually get into and try to understand how things work by looking at them up close.”

The center of our Milky Way galaxy captured by the Spitzer Space Telescope's infrared cameras.
The center of our Milky Way galaxy captured by the Spitzer Space Telescope’s infrared cameras. NASA, JPL-Caltech, Susan Stolovy (SSC/Caltech) et al.

The center of the Milky Way, shown here in an infrared image captured by NASA’s now-retired Spitzer Space Telescope, is a strange place with features like an enormous and hungry supermassive black hole and unusual stretchy G objects which behave in unexpected ways. The area is known to be where most of the Milky Way’s stars formed when the galaxy was young, between 8 and 13.5 billion years ago.

But since then star formation in this region has dropped off, and the flow of this cold gas could be contributing to that. “Galaxies can be really good at shooting themselves in the foot,” one of the authors, Professor Naomi McClure-Griffiths of the Australian National University, explained in the statement. “When you drive out a lot of mass, you’re losing some of the material that could be used to form stars, and if you lose enough of it, the galaxy can’t form stars at all anymore.

“So, to be able to see hints of the Milky Way losing this star-forming gas is kind of exciting — it makes you wonder what’s going to happen next!”

The findings are published in the journal Nature.

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