14 million years ago a series of events led to the creation of a large bubble that is responsible for the formation of all young stars near Earth, according to a study published Nature.
This is the first time that a group of scientists, led by the Harvard and Smithsonian Center for Astrophysics (CfA), explain how nearby star formation began, using simulations, new techniques, and data.
The study is based on a 3D space-time animation, which reveals that all young stars and star-forming regions – within 500 light-years of Earth – lie on the surface of a known giant bubble. like the Local Bubble.
Astronomers have known about it for decades, but now the beginnings of that bubble and its impact on the gas around it can be seen and understood.
The space-time animation shows how a series of supernovae that first erupted 14 million years ago pushed interstellar gas outward, creating a bubble-like structure with a surface ripe for star formation.
Currently, seven known star-forming regions or molecular clouds – dense areas in space where stars can form – lie on the surface of the bubble.
“We have calculated that some fifteen supernovae have exploded over millions of years to form the Local Bubble that we see today”, noted Catherine Zucker, who completed the work while at the CfA.
The bubble is not inactive and continues to grow slowly, at about six kilometers per second, but “it has lost most of its momentum and has stabilized in terms of speed,” according to the expert.
The speed of expansion of the bubble, as well as the past and present trajectories of young stars forming on its surface, were deduced using data obtained by Gaia, a space observatory launched by the European Space Agency (ESA).
With the new system, the history of star formation around us can be reconstructed, “using a wide variety of independent clues: supernova models, stellar movements and new and exquisite 3D maps of the material surrounding the Local Bubble,” explained another of the authors, Alyssa Goodman, Harvard University.
When the first supernovae that created the Local Bubble exploded, “our Sun was a long way from the action,” added co-author João Alves, a professor at the University of Vienna.
But nevertheless, About five million years ago, the Sun’s path through the galaxy took it right inside the bubble, and it is, “just luckily, almost right in the center” of it.
Astronomers first proposed that superbubbles were ubiquitous in the Milky Way nearly fifty years ago and “now we have evidence,” Goodman said.
The scientist likens the discovery to a cheese-like Milky Way with many holes, which are ejected by supernovae, and new stars can form in the cheese around the holes created by dying stars.
The team now plans to map more interstellar bubbles to get a complete 3D view of their location, shape and size.
Tracing the bubbles and the relationship between them will allow astronomers to understand the role that dying stars play in the birth of new ones and in the structure and evolution of galaxies like the Milky Way.
500 light-years radius from Earth – lie on the surface of a giant bubble known as the Local Bubble.
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