Smith Cloud Expected to Crash Into Milky Way in 30 Million Years
Posted on February 3, 2016
The Smith Cloud is expected to crash into the Milky Way in about 30 million years. It is a giant starless gas cloud traveling at nearly 700,000 miles per hour. The cloud is 11,000 light-years long and 2,500 light-years across.
Astronomers studying the cloud have determined that its material originated in the Milky Way over 70 million years ago. Astronomers compared sulfur measurements from Hubble's Cosmic Origins Spectrograph with hydrogen measurements made by Green Bank Telescope (GBT). Using this information they were able to estimate the chemical makeup of the cloud. They found it is as rich in sulfur as the Milky Way's outer disk.
University of Notre Dame astrophysicist Nicolas Lehner says in a statement, "We have found several massive gas clouds in the Milky Way halo that may serve as future fuel for star formation in its disk, but, for most of them, their origins remain a mystery. The Smith Cloud is certainly one of the best examples that shows that recycled gas is an important mechanism in the evolution of galaxies."
NASA says the cloud will ignite a "spectacular burst of star formation" when it crashes into the Milky Way. It has enough gas to fuel up to 2 million new suns.
A research paper on the metallicity and origin of the Smith Cloud was published here in The Astrophysical Journal. More images of the Smith Cloud can be found here on the Hubble Site.