Diffuse inter-filament gas is likely a key fuel source for massive star formation

Researchers from Kyushu University have found that diffuse gas surrounding dense filaments in a nearby stellar nursery plays a larger role than previously thought in star formation. By tracking gas movement in the Monoceros R2 hub-filament system, they discovered that low-density gas contributes to hub growth through both direct inflow and by replenishing nearby dense filaments.

Their findings suggest that overlooking this diffuse gas could significantly underestimate the material available for building massive stars. Stars form within interstellar clouds of gas and dust, with long, threadlike structures called filaments often converging into dense central regions called hubs, where clusters of stars and massive stars are born.

Previous studies have shown that dense gas travels along filaments into the hub, but less is known about the lower-density gas filling the spaces between filaments, leaving an incomplete picture of how these nurseries accumulate material. In their study published in The Astrophysical Journal Letters, assistant professor Jihye Hwang and associate professor Doris Arzoumanian analyzed gas motions using observations of carbon monoxide isotopes from the Nobeyama 45-m radio telescope.

They found that dense filaments flow toward the hub much faster than inter-filament regions, but at least 30% of the diffuse gas moves sideways into filaments, replenishing them before continuing toward the hub. Accounting for both dense and diffuse gas increases the estimated material flowing onto the hub by about 50%.