Largest image of its kind shows hidden chemistry at the heart of the Milky Way

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 Telescope, Chile, this rich dataset 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.

"It's a place of extremes, invisible to our eyes, but now revealed in extraordinary detail," says Ashley Barnes, an astronomer at the European Southern Observatory (ESO) who is part of the team involving Liverpool John Moores University, that is analyzing the new data.

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 300 light-years. It harbors dense clouds of gas and dust, surrounding the supermassive black hole at the center of our galaxy. "

The ALMA CMZ Exploration 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, in powerful supernova explosions, and even hypernovae," says ACES leader Steve Longmore, a professor of astrophysics at Liverpool John Moores University, UK

"By studying how stars are born in the CMZ, we can also gain a clearer picture of how galaxies grew and evolved," Longmore adds. "We believe the region shares many features with galaxies in the early Universe, where stars were forming in chaotic, extreme environments."

The region is the only galactic nucleus close enough to Earth for us to study in such fine detail, and includes gas structures dozens of light-years across all the way down to small gas clouds around individual stars.

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. 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.

"We anticipated a high level of detail when designing the survey, but we were genuinely surprised by the complexity and richness revealed in the final mosaic," says Katharina Immer, an ALMA astronomer at ESO who is also part of the project.

The data from ACES are presented in five papers, now accepted for publication in Monthly Notices of the Royal Astronomical Society.

Provided by Liverpool John Moores University