(ORDO NEWS) — The Earth and the Sun are inside a huge “bubble” of rarefied gas. The new work of scientists has demonstrated how it came into being and how we ended up almost at the very center of it.
The solar system moves through a vast desert region of the Galaxy filled with about 10 times more rarefied gas than the ordinary interstellar medium. We are now almost in the center of this Local Bubble , which stretches for hundreds of light years in all directions.
It is believed that the bubble formed 10-20 million years ago as a result of a series of supernova explosions. Their shock waves created compaction of gas and stimulated the birth of new stars, which today surround our much more ancient Sun, and part of the matter ended up in the “shell” of the Local Bubble.
Scientists at the Smithsonian Astrophysical Observatory (CfA) recently mapped the area, simulated the evolution of the Local Bubble, and confirmed previous guesses about its appearance. An article by Catherine Zucker and her colleagues is published in the journal Nature.
Also, the work is described in the message of the press service of the CfA. The authors posted the most vivid result of it online, in the form of an interactive 3D animation of the Local Bubble, which shows both key stars and star-forming regions.
For the work, we used the observations of the Gaia astrometric space telescope , which tracks the exact positions and movements of billions of stars, making the most accurate map of the Milky Way’s neighborhoods closest to us.
These data showed that almost all neighboring young stars and star-forming regions are located on the surface of the Local Bubble. This picture is fully consistent with the supernova hypothesis, because it is the outer region of the shock wave that turns out to be the most dense, allowing the birth of stars.
Further, scientists have modeled this process, “rewinding” the motion of stars and gas clouds “back in time”, right up to the moment of the first explosions.
This work showed that the Local Bubble originated about 14.4 million years ago and involved a total of about 15 supernovae that flared up over several million years. At first, the bubble expanded at a speed of almost 100 kilometers per second, although now its expansion has slowed down to 6.7 kilometers per second.
“When the first supernova created the Local Bubble, the Sun was far from the scene,” says one of the authors of the work. “But about five million years ago, moving through the Galaxy, the Sun entered the bubble and now, by pure chance, is almost exactly in its center.”
Scientists speculate that the Milky Way may contain many such bubbles, created by supernovae in low-density regions. And, perhaps, new data from the Gaia telescope will allow them to be found.
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