Washington: A team of researchers has revealed that the old adage “what goes up must come down” is ringing true for an immense cloud of hydrogen gas that is heading towards our galaxy at nearly 700,000 miles per hour.
Though hundreds of enormous high-velocity gas clouds whiz around the outskirts of our galaxy, this so-called “Smith Cloud” is unique because its trajectory is well known.
New Hubble observations suggest it was launched from the outer regions of the galactic disk, around 70 million years ago. The cloud was discovered in the early 1960s by doctoral astronomy student Gail Smith, who detected the radio waves emitted by its hydrogen.
The cloud is on a return collision course and is expected to plow into the Milky Way’s disk in about 30 million years. When it does, astronomers believe it will ignite a spectacular burst of star formation, perhaps providing enough gas to make 2 million suns.
Team leader Andrew Fox said that the galaxy is recycling its gas through clouds, the Smith Cloud being one example, and will form stars in different places than before. Hubble’s measurements of the Smith Cloud are helping us to visualize how active the disks of galaxies are.
Astronomers have measured this comet-shaped region of gas to be 11,000 light-years long and 2,500 light-years across. If the cloud could be seen in visible light, it would span the sky with an apparent diameter 30 times greater than the size of the full moon.
The study appears in The Astrophysical Journal Letters. (ANI)