The collision could result in the formation of two-million suns!
Have you heard of the saying “what goes up must come down?” Well, it turns out it doesn’t just apply to things here on Earth, but also some objects in space. Hubble Space Telescope astronomers are tracking an invisible hydrogen gas cloud that may have originated in the Milky Way galaxy — and it is speeding back towards us at nearly 700,000 miles per hour.
Fast-moving gas clouds are definitely nothing new to the universe, in fact, there are hundreds of them around our galaxy alone. However, this “Smith Cloud,” named after doctoral astronomy student Gail Smith who first detected the radio waves emitted by the cloud’s hydrogen in the early 1960s, is unique because astronomers know its trajectory.
SEE ALSO: Mysterious Object is 570 Billion Times Brighter than the Sun
Hubble observations suggest that it was ejected from the outer regions of our galaxy nearly 70 million years ago, and now it is on a return collision. The collision is expected to occur in about 30 million years, and when it does, it may result in a massive burst of star formation — as many as two-million suns!
“The cloud is an example of how the galaxy is changing with time,” explained team leader Andrew Fox of the Space Telescope Science Institute in Baltimore, Maryland in a press release. “It's telling us that the Milky Way is a bubbling, very active place where gas can be thrown out of one part of the disk and then return back down into another.”
This gas cloud is comet-shaped and huge! Astronomers have estimated it to be 11,000 light-years long and 2,500 light-years across. To put that into perspective, if we could see it in the sky right now, it would be about 30 times bigger than a full moon.
Below is a visualization of the track of this enormous gas cloud.
photo credit: NASA/ESA/A. Feild (STScI). Images have been cropped.
Astronomers thought the Smith Cloud could be a failed, starless galaxy, or gas falling into the Milky Way from intergalactic space, but if either of these were true, the cloud would contain mainly hydrogen and helium. However, if it came from our galaxy, it would contain more elements found within our sun.
To determine the cloud’s chemical composition, the team used the Hubble Space Telescope. First they observed ultraviolet light from three active galaxies located billions of light-years beyond the cloud, and then using Hubble’s Cosmic Origins Spectrograph, they measured how this light filtered through the cloud.
In particular, they looked for sulfur in the cloud which can absorb ultraviolet light, and is also a good indicator of how many other elements are in the cloud. “By measuring sulfur, you can learn how enriched in sulfur atoms the cloud is compared to the sun,” said Fox.
So what did the astronomers find? It turns out that the Smith Cloud is just as rich in sulfur as the Milky Way’s outer disk — a region about 40,000 light-years from the galaxy’s center and about 15,000 light-years farther out than our sun and solar system. This means that the cloud was more than likely launched from within the Milky Way, and it is now on its way back — like a boomerang.
And in typical science fashion, solving the mystery of the Smith Cloud’s origin raised new questions: How did the cloud get to where it is now? What event could have ejected it from the Milky Way's disk, and how did it remain intact? Could it be a region of dark matter that passed through the disk and captured Milky Way gas?
So many questions! However, we will have to wait and see what further research finds to get some answers.
Facebook comments