Gas falling into a giant star-forming cloud behaves like it is hitting a 'slow zone,' decelerating as it gets closer to the center instead of speeding up.
April 1, 2026
Original Paper
An inverted infall profile for the collapse of the massive star-forming IRDC SDC335.579-0.292
arXiv · 2603.30029
The Takeaway
Gravity is expected to accelerate objects as they fall toward a massive center. This discovery of an 'inverted' speed profile suggests that massive stars aren't formed by a simple collapse, but by a complex 'traffic flow' where material is forced to brake and rearrange itself at specific distances.
From the abstract
There is increasing evidence for global collapse of clumps over parsec-scales in massive star formation regions. Such collapse may result in characteristic molecular line emission profiles but the spatial variation of such lines has rarely been quantitatively examined. Here we explore the infall properties using the spatially-resolved HCO$^+$ J=1--0 and H$^{13}$CO$^+$ J=1--0 maps of the massive infrared dark cloud (IRDC) SDC335.579-0.292. We compare the observations with the analytical Hill5 mod