ALMA Maps Molecular Gas Across Barred Spiral Galaxy Messier 83
Using ALMA, astronomers mapped carbon monoxide emission from molecular gas in Messier 83 at about 150-light-year resolution. The ratio of two emission lines varies from the galaxy's center through its bar and spiral arms, following patterns tied to galactic rotation and structure. The results suggest that large-scale dynamics, rather than feedback from newborn stars alone, largely shape the life cycle of star-forming gas in barred spirals.
Messier 83 lies about 15 million light-years away in Hydra and is also called the Southern Pinwheel Galaxy. Lacaille found it in 1752; at magnitude 7.5, it is bright enough for binocular viewing, especially in May. It is roughly half the Milky Way's size.
ALMA observed two carbon monoxide lines to trace gas density and temperature at roughly 150-light-year resolution. The line ratio peaks at the nucleus, declines across the bar, increases near the bar's end, then weakens in the outer disk. This sequence tracks the galaxy's rotation and structure.
Findings may shape how astronomers interpret star formation in barred spirals, influencing future surveys and models. This could affect observatories, data scientists, educators, and public audiences by refining expectations for where gas is dense or warm. It may also support better simulations of galaxy evolution, though direct everyday societal effects are likely indirect and long-term.