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 centre.
“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 analysing 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 harbours dense clouds of gas and dust, surrounding the supermassive black hole at the centre of our galaxy."
Chemistry detectives
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.
The most massive stars in our galaxy, many of which live fast and die young
Professor Steven Longmore, LJMU
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 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 at LJMU's Astrophysics Research Institute.
“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.
Unparalleled detail
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.
The international ACES team is composed of over 160 scientists ranging from Master’s students to retirees, working at more than 70 institutions across Europe, North and South America, Asia, and Australia. The project is led by Principal Investigator Steven Longmore (Liverpool John Moores University, UK), together with co-PIs Ashley Barnes(European Southern Observatory, Germany), Cara Battersby (University of Connecticut, USA), John Bally (University of Colorado Boulder, USA), Laura Colzi (Centro de Astrobiología, Madrid, Spain), Adam Ginsburg (University of Florida, USA), Jonathan Henshaw (Max Planck Institute for Astronomy, Heidelberg, Germany), Izaskun Jiménez-Serra (Centro de Astrobiología), J. M. Diederik Kruijssen (COOL), Elisabeth Mills (University of Kansas, USA), Maya Petkova (Chalmers University of Technology, Sweden), Mattia Sormani (University of Insubria, Italy), Robin Tress (École Polytechnique Fédérale de Lausanne, Switzerland), Daniel Walker (UK ALMA Regional Centre Node, University of Manchester, UK), and Jennifer Wallace (Connecticut).
Within ACES, the ALMA data reduction working group is coordinated by Adam Ginsburg, Daniel Walker, and Ashley Barnes, and includes Nazar Budaiev (Florida), Laura Colzi (Centro de Astrobiología), Savannah Gramze (Florida), Pei-Ying Hsieh (National Astronomical Observatory of Japan, Mitaka, Tokyo, Japan), Desmond Jeff (Florida), Xing Lu (Shanghai Astronomical Observatory, Chinese Academy of Sciences, China), Jaime Pineda (Max-Planck-Institut für extraterrestrische Physik,Germany), Marc Pound (University of Maryland, USA), and Álvaro Sánchez-Monge (Institut de Ciències de l’Espai, CSIC, Bellaterra, Spain; Institut d’Estudis Espacials de Catalunya, Castelldefels, Spain), together with more than 30additional team members who contributed to the data reduction effort.
The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science and Technology Council (NSTC) in Taiwan and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI). ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
