A Mushroom-shaped Structure from the Impact of a Cloud with the Galactic Disk

Abstract

We propose that the mushroom-shaped structure of the Galactic worm GW 123.4--1.5 is created by a cloud collision with the Galactic gas disk. A hydrodynamic simulation shows that a mushroom-shaped structure is created after the cloud crosses the Galactic midplane. The lifetime of the mushroom-shaped structure is of order the dynamical time scale of the disk, \sim 10^7 years. We find that the velocities across the cap of the mushroom-shaped structure in the simulation are consistent with the observed values. The simulation also predicts a structure on the opposite side of the Galactic plane which is created by the Kelvin-Helmholtz instability after the cloud passes through the disk.

arXiv comment6 pages, 5 figures, accepted for publication in A&A, color figures and movies at http://www.astro.uwo.ca/~kudoh/mushroom/

References in corpus (3)

• High Velocity Rain: The Terminal Velocity of Model of Galactic Infall
• Mushroom-Shaped Structures as Tracers of Buoyant Flow in the Galactic Disk
• Galactic Worm 123.4-1.5: A Mushroom-shaped HI Cloud

Cited by in corpus (5)

• The Ophiuchus Superbubble: A Gigantic Eruption from the Inner Disk of the Milky Way
• The Evolution of Gas Clouds Falling in the Magnetized Galactic Halo: High Velocity Clouds (HVCs) Originated in the Galactic Fountain
• How was the mushroom-shaped GW 123.4--1.5 formed in the Galactic disk?
• A Search for Narrow Vertical Structures in the Canadian Galactic Plane Survey
• Cosmic Rays and Non-thermal Emission Induced by Accretion of Cool Gas onto the Galactic Disk