Hubble observes vast gas cloud set to collide with the Milky Way
For the first time,astronomers have used the Hubble Space Telescope to measure thechemical composition of a vast gas cloud that is set to collide withthe Milky Way. Upon impact, the Smith Cloud will act as the catalystfor a colossal burst of star creation.
It is believed that theSmith Cloud was launched from the outer disk around 70 million yearsago. The existence of the body stands as tribute to the active natureof the Milky Way, and highlights a mechanism by which our galaxyrecycles and redistributes its star creating materials.
Over the course ofmillions of years as the Smith Cloud moved along its boomerangtrajectory, the Milky Way's gravity moulded the gaseous body into acomet-like visage some 2,500 light-years across, and an impressive11,000 light-years in length. If visible to the naked eye, the SmithCloud would cover an area the equivalent of 30 full Moons in thenight sky.
It was initiallytheorized that the Smith Cloud had originated outside of our galaxy,instead representing a massive intergalactic cloud or even a failed,starless galaxy, which was being drawn into the Milky Way by herstrong gravitational influence.
For the recent study,the researchers were able to estimate the quantity of heaviermaterials in the Smith Cloud by harnessing the power of Hubble'sCosmic Origins Spectrograph. The team analysed the signature of lightemitting from three galaxies located billions of light-years beyondthe cloud, and observed how the light filters through it.
The results of theanalysis were inconsistent with either of the theories that placedthe origin of the cloud outside the Milky Way. Any cloud originatingoutside of our galaxy would contain an abundance of hydrogen andhelium, rather than the heavier materials Hubble detected in theSmith Cloud. According to the researchers, these materials were mostlikely enriched by supernova explosions taking place within the MilkyWay.
Astronomers believethat when the Smith Cloud rejoins the Milky Way that the massiveinfusion of new material will be responsible for the creation of upto two million Suns.