Astronomers have identified ten high-velocity molecular clouds within the barred spiral galaxy M83, offering a fresh perspective on how galaxies sustain star formation over extended periods. These clouds move at speeds significantly different from the galaxy's disk rotation, suggesting that galaxies may acquire fresh gas from external sources. This process could potentially trigger new star formation.
The research, spearheaded by Maki Nagata from the University of Tokyo's Institute of Astronomy, utilized data from the Atacama Large Millimeter/submillimeter Array (ALMA). The study, published in The Astrophysical Journal in May 2025, provides detailed insights into these unusual clouds. The high-velocity clouds (HVCs) detected in M83 have radii ranging from 30 to 80 parsecs and masses approximately equal to 10^5 solar masses.
These HVCs exhibit velocity dispersions ranging from 3 to 20 km/s, indicating greater variability compared to typical disk molecular clouds. Their kinetic energies exceed those of single supernova explosions, implying an external origin. This discovery challenges the notion of galaxies as isolated systems, suggesting they can grow by accreting gas from their surroundings.
The inflow of dense molecular gas into M83 may directly contribute to future star formation, highlighting the interconnected nature of galaxies in the universe. Future studies will aim to further investigate the origins of these high-velocity clouds and their impact on galactic growth and development.