Astronomers using CSIRO’s Australian SKA Pathfinder (ASKAP) telescope has discovered that a nearby dwarf galaxy called the Small Magellanic Cloud has cold hydrogen outflows extending at least 6,500 light-years from its star-forming bar.
A radio image of hydrogen gas in the Small Magellanic Cloud as observed by CSIRO’s ASKAP radio telescope. Image credit: Naomi McClure-Griffiths et al / CSIRO’s ASKAP Telescope.
Hydrogen is the most abundant element in the Universe, and is the main ingredient of stars.
“The ASKAP radio telescope covered the entire Small Magellanic Cloud in a single shot and photographed its hydrogen gas with unprecedented detail,” said Dr. David McConnell, a researcher at the CSIRO Astronomy and Space Science.
“The features of the radio images were more than three times finer than previous images of this dwarf galaxy, which allowed us to probe the interactions between the galaxy and its environment with more accuracy,” said Professor Naomi McClure-Griffiths, an astronomer at the Australian National University.
“We were able to observe a powerful outflow of hydrogen gas from the Small Magellanic Cloud,” she added.
“The implication is the galaxy may eventually stop being able to form new stars if it loses all of its gas. Galaxies that stop forming stars gradually fade away into oblivion.”
The outflow observed by the team is very cold and may have formed during a period of active star formation 25-60 million years ago.
“The total mass of atomic gas in the outflow is about 107 solar masses — that is, about 3% of the total atomic gas of the Small Magellanic Cloud,” the astronomers said.
“The mass flow rate is up to one order of magnitude greater than the galaxy’s star-formation rate.”
“The result is also important because it provides a possible source of gas for the enormous Magellanic Stream that encircles the Milky Way,” Professor McClure-Griffiths said.
“Ultimately, the Small Magellanic Cloud is likely to eventually be gobbled up by our Milky Way Galaxy.”
The findings are published in the journal Nature Astronomy.
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N.M. McClure-Griffiths et al. Cold gas outflows from the Small Magellanic Cloud traced with ASKAP. Nature Astronomy, published online October 29, 2018; doi: 10.1038/s41550-018-0608-8
