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Largest ALMA image ever shows the molecular gas in the centre of the Milky Way Credit: ALMA(ESO/NAOJ/NRAO)/S. Longmore et al. Background: ESO/D. Minniti et al.

This article was adapted from a version originally published by the European Southern Observatory (ESO). .

Astronomers have captured the central region of our Milky Way in a striking new image, unveiling a complex network of filaments of cosmic gas in unprecedented detail. Obtained with the (ALMA), this rich dataset—the largest ALMA image to date—will allow astronomers to probe the lives of stars in the most extreme region of our galaxy, next to the supermassive black hole at its center.

Images revealing the distributions of various molecules in the center of the galaxy: carbon monosulfide, isocyanic acid, silicon monoxide, sulfur monoxide and cyanoacetylene. Credit: ALMA (ESO/NAOJ/NRAO)/S. Longmore et al.

“It’s a place of extremes, invisible to our eyes, but now revealed in extraordinary detail,” said Ashley Barnes, an astronomer at the European Southern Observatory (ESO) in Germany who is part of the team that obtained the new data.

The research was led by an open collaboration of scientists known as the (ACES). John Bally, professor emeritus in the Department of Astrophysical and Planetary Sciences at ���������� Boulder, serves as co-principal investigator for ACES. The collaboration also includes former ���������� Boulder graduate students Cara Battersby and Adam Ginsburg.

The observations provide a unique view of the cold gas—the raw material from which stars form—within the so-called Central Molecular Zone (CMZ) of our galaxy. It is the first time the cold gas across this whole region has been explored in such detail.

The region featured in the new image spans more than 650 light-years. It harbors dense clouds of gas and dust, surrounding the supermassive black hole at the center of our galaxy.

The dataset reveals the CMZ like never before, from gas structures dozens of light-years across all the way down to small gas clouds around individual stars.

Bally studies how new stars emerge in this extreme environment. Fewer stars form in the galactic center than scientists once predicted—a long-running mystery that data like the news ACES observations could help to answer.

“Intense radiation, winds powered by massive stars, supernova explosions, and accreting neutron stars and stellar-mass black holes constitute ‘feedback’ that opposes the tendency of clouds to collapse due to their self-gravity and fragment into dense, star-forming cores,” Bally said.

The gas that ACES specifically explores is cold molecular gas. The survey unpacks the intricate chemistry of the CMZ, detecting dozens of different molecules, from simple ones such as silicon monoxide to more complex organic ones like methanol, acetone or ethanol.

Cold molecular gas flows along filaments feeding into clumps of matter out of which stars can grow. In the outskirts of the Milky Way we know how this process happens, but within the central region the events are much more extreme.

“The CMZ hosts some of the most massive stars known in our galaxy, many of which live fast and die young, ending their lives in powerful supernova explosions, and even hypernovae,” said ACES leader Steve Longmore, a professor of astrophysics at Liverpool John Moores University, UK.

To collect this new dataset, astronomers used ALMA, which is operated by ESO and partners in Chile’s Atacama Desert. In fact, this is the first time such a large area has been scanned with this facility, making this the largest ALMA image ever. Seen in the sky, the mosaic—obtained by stitching together many individual observations like putting puzzle pieces together—is as long as three full Moons side-by-side.

The are presented in five papers accepted for publication in Monthly Notices of the Royal Astronomical Society, with a sixth in the final review stages.

“The upcoming ALMA , along with ESO’s , will soon allow us to push even deeper into this region—resolving finer structures, tracing more complex chemistry, and exploring the interplay between stars, gas and black holes with unprecedented clarity,” said Barnes. “In many ways, this is just the beginning.”