Slow death of nearby galaxy

Astronomers observed a powerful outflow of hydrogen gas from the Small Magellanic Cloud.

A radio image of hydrogen gas in the Small Magellanic Cloud as observed by CSIRO's ASKAP telescope. Image credit: Naomi McClure-Griffiths et al, CSIRO's ASKAP telescope.
A radio image of hydrogen gas in the Small Magellanic Cloud as observed by CSIRO's ASKAP telescope. Image credit: Naomi McClure-Griffiths et al, CSIRO's ASKAP telescope.

A team of astronomers at the CSIRO in collaboration with The Australian National University have detected the slow death of nearby dwarf galaxy. With small gravitational potential wells, this galaxy losing their star-forming material in the presence of intense stellar feedback.

Astronomers studied the Small Magellanic Cloud (SMC), which is a tiny fraction of the size and mass of the Milky Way galaxy using images captured by CSIRO’s powerful Australian SKA Pathfinder (ASKAP) radio telescope array.

The images captured were three times finer than previous SMC images. This enabled astronomers to precisely examine the interactions between the small galaxy and its environment.

Slow death of nearby galaxy

Professor McClure-Griffiths from the Research School of Astronomy and Astrophysics at ANU said, “We were able to observe a powerful outflow of hydrogen gas from the Small Magellanic Cloud. 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. It’s sort of a slow death for a galaxy if it loses all of its gas.”

Professor McClure-Griffiths said, “the discovery, which is part of a project that investigates the evolution of galaxies, provided the first clear observational measurement of the amount of mass lost from a dwarf galaxy.”

“The result is also important because it provides a possible source of gas for the enormous Magellanic Stream that encircles the Milky Way. Ultimately, the Small Magellanic Cloud is likely to eventually be gobbled up by our Milky Way.”

CSIRO co-researcher Dr. David McConnell said, “ASKAP was unrivaled in the world for this kind of research due to the unique radio receivers that give it a panoramic view of the sky. The telescope covered the entire SMC galaxy in a single shot and photographed its hydrogen gas with unprecedented detail.”

“ASKAP will go on to make state-of-the-art pictures of hydrogen gas in our own Milky Way and the Magellanic Clouds, providing a full understanding of how this dwarf system is merging with our own galaxy and what this teaches us about the evolution of other galaxies.”

The study is published in Nature Astronomy.