Origin of the IRAS Vela Shell: New Insights from 3D Dust Mapping

Bore (Annie) Gao

Wednesday, Dec. 4th, 9:00CET

The IRAS Vela Shell (IVS) is a cavity located towards the Gum Nebula, a prominent region of H-alpha emission in the local Milky Way that has been collectively shaped by a variety of galactic stellar feedback over the past several million years. In this work, we constrain the 3D spatial geometry of the IVS using a parsec-resolution 3D dust map and contextualize it within the broader Gum Nebula region. Our analysis shows that the IVS contains a dense, bowl-like structure slightly below the Galactic plane, with a more diffuse component at higher latitudes. We calculate the shell mass, and present its geometry in 3D for the first time. Combining with the past studies on the shell expansion, we also calculate its momentum associated with the expansion. We find a strong spatial correlation between the morphology of the dust-traced IVS and the morphology of the Gum nebula's H-alpha emission when projected onto the plane of the sky. We quantify the contribution of stellar winds and supernova to the shell's formation and find supernova to be the dominant energy source. Using new astrometric constraints from Gaia, we perform a dynamical traceback of potential nearby sources of feedback, and find several young massive clusters that likely produced the supernova responsible for powering the shell's expansion.