Massive Gas Cloud Headed Straight for Milky Way Galaxy; Inner 'Force Field' to Soften its Blow
ByA giant gas cloud is headed straight for the Milky Way Galaxy, but it has a deep-seeded magnetic force field that will likely soften its blow, giving scientists insight to such events.
According to a press release, Astronomers using the National Science Foundation's Karl G. Jansky Very Large Array (VLA) and Robert C. Byrd Green Bank Telescope (GBT) said the force field discovery may explain how a high velocity cloud (HVC) can seamlessly merge with a galaxy.
The Smith Cloud is traveling at a rate of 150 miles per second and will hit out Galaxy disk in 30 million years. The inevitable collision, astronomers believe, will fuel the galaxy and set of a spectacle of star formations.
"The million-degree upper atmosphere of the Galaxy ought to destroy these hydrogen clouds before they ever reach the disk, where most stars are formed," said study lead author Alex Hill, an astronomer at Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO). "New observations reveal one of these clouds in the process of being shredded, but a protective magnetic field shields the cloud and may help it survive its plunge."
Hill and is team published their work in Friday's edition of the Astrophysical Journal.
"We have long had trouble understanding how HVCs reach the Galactic disk," said Hill. "There's good reason to believe that magnetic fields can prevent their 'burning up' in the halo like a meteorite burning up in Earth's atmosphere."
The gas clouds that slam into galaxy disks may be massive, but their gas makeup is soft and weak and could not survive such an impact on its own. Such clouds seemingly wander aimlessly around space, leading scientists to believe they are leftovers from other galaxy's formations.
"The Smith Cloud is unique among high-velocity clouds because it is so clearly interacting with and merging with the Milky Way," said Felix J. Lockman, an astronomer at the National Radio Astronomy Observatory (NRAO) in Green Bank, W.Va. "Its comet-like appearance indicates it's already feeling the Milky Way's influence."
The Smith Cloud does not appear to have any stars, so the only way to see it would be with a particular telescope. If it were visible, it would approximately match the size of the Orion constellation.
"Our Galaxy is in an incredibly dynamic environment," said Hill, "and how it interacts with that environment determines whether stars like the Sun will continue to form."