14 million years ago, a series of events led to the formation of a large bubble responsible for the formation of all the young stars near Earth, According to a study published on Wednesday (12.01.2022) temper nature.
This is the first time that a team of scientists, led by the Harvard and Smithsonian Center for Astrophysics (CfA), has explained how nearby stars began to form, using simulations, techniques and new data.
The local bubble, within a radius of 500 light-years from Earth
The study is based on 3D animation of space-time, 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 of its existence for decades, but now the beginnings of that bubble and its effect on the surrounding gas can be seen and understood.
Bubble carved by supernovae
Space-time animations show how a series of supernovae that first erupted 14 million years ago pushed interstellar gas outward, forming a bubble-shaped structure with a surface ready for star formation.
Currently, there are seven known star-forming regions or molecular clouds – dense regions in space where stars can form – on the bubble’s surface.
“We calculated that about 15 supernovae exploded over millions of years to form the local bubble we see today,” said Catherine Zucker, who completed work at CfA.
slow growth
The bubble is not inert and continues to grow slowly, at about six kilometers per second, but it has “lost most of its momentum and stabilized in terms of velocity,” according to the expert.
The bubble’s expansion velocity, as well as the past and present trajectories of young stars forming on its surface, were inferred using data acquired by the ESA’s Gaia space observatory.
With the new system, it is possible to reconstruct the history of star formation around us, “using a variety of independent clues: supernova models, stellar motions and new and fascinating 3D maps of the material surrounding the local bubble,” explained another of the authors Alyssa Goodman, University of Harvard.
Currently, there are seven known star-forming regions or molecular clouds – dense regions in space where stars can form – on the bubble’s surface.
The opportunity to be in the center
Co-author João Alves, a professor at the University of Vienna, added that when the first supernovae erupted leaving the local bubble, “our sun was very far from the event.”
However, about five million years ago, the path of the Sun took her through the galaxy inside the bubble, which is “fortunately, almost in the middle of it.”
Astronomers initially suggested that supernovae have been ubiquitous in the Milky Way for nearly fifty years and “we now have evidence,” Goodman said.
“Swiss cheese”
The scientist compares the discovery to the Milky Way, which looks like Swiss cheese with many holes, which are emitted by supernovae, and new stars can form in the cheese around the holes created by dying stars.
The team now plans to draw more bubbles between the stars to get a full 3D view of their location, shape and size.
Tracking the bubbles and their relationship will allow astronomers to understand the role of dying stars in the birth of new bubbles and in the structure and evolution of galaxies such as the Milky Way.
FEW (EFE, STScI, temper nature)
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