Milky Way’s Core Revealed in Unprecedented Detail by ALMA

Astronomers have captured the most detailed image yet of the central region of the Milky Way galaxy, unveiling a complex network of gas and dust that fuels star formation around the supermassive black hole Sagittarius A* (Sgr A*). The observations, made by the Atacama Large Millimeter/submillimeter Array (ALMA), provide new insights into the extreme conditions at the heart of our galaxy.

Mapping the Central Molecular Zone

For the first time, the Central Molecular Zone (CMZ) – a region spanning over 650 light-years – has been mapped with unprecedented detail. The CMZ is the most extreme location in the Milky Way, harboring Sgr A* and dense clouds of gas and dust. This region, typically invisible to the naked eye, has been brought into focus by ALMA’s powerful capabilities. The resulting image is a mosaic assembled from numerous observations, revealing the distribution of cold molecular gas, the raw material for star birth.

A Network of Gas Filaments

The ALMA observations reveal a network of cold gas filaments, tens of light-years across, interconnected with smaller gas clouds surrounding individual stars. These filaments act like giant roots, channeling cold molecular gas into clumps where stars are born. The gas, though cold, still maintains temperatures tens to hundreds of degrees above absolute zero.

Complex Chemistry at the Galactic Center

The survey, known as the ALMA CMZ Exploration Survey (ACES), has also uncovered the complex chemistry of the CMZ. ALMA detected dozens of different molecules, ranging from simple compounds like silicon monoxide to more complex organic molecules such as methanol, acetone, and ethanol. This makes the galactic center a vast chemical laboratory on a galactic scale.

Star Formation in Extreme Conditions

Even as astronomers understand star formation in the outer regions of the Milky Way, the process is far more challenging to study at the galactic center. The intense gravity near Sgr A*, combined with high pressure and strong radiation, creates extreme conditions. Despite these challenges, some of the most massive stars in the Milky Way are born in this region, living short but dramatic lives before ending in supernova or hypernova explosions.

Understanding Stellar Evolution

The ACES project aims to understand how these extreme conditions affect the birth and evolution of stars. By studying the galactic center, astronomers hope to determine whether the same theories of stellar evolution apply in such harsh environments.

Future Exploration

These observations represent just the beginning of a deeper exploration of the Milky Way’s core. Future improvements to ALMA’s sensitivity, coupled with the capabilities of the Extremely Large Telescope (ELT), will allow astronomers to probe even smaller structures within the CMZ and further investigate the interactions between gas, stars, and the supermassive black hole at the galaxy’s heart.

Sources

• Sagittarius A* – Wikipedia
• ALMA reveals Milky Way’s core in largest-ever mosaic, tracing hidden chemistry
• Astronomers unveil strong magnetic fields spiraling at the edge of Milky Way’s central black hole