Research reveals that Earth is at the center of a bubble carved by supernovae

Artist’s illustration of the Local Bubble with star formation on the surface of the bubble.

14 million years ago, a series of events led to the creation of a large bubble that is responsible for the formation of all the young stars close to Earth., according to a study published last Wednesday Nature.

This is the first time that a group of scientists, led by the Harvard-Smithsonian Center for Astrophysics (CfA), have explained how nearby star formation began, using simulations, new techniques, and data.

The Local Bubble, within 500 light years of Earth

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 of its existence for decades, but now the beginnings of that bubble and its impact on the gas around it can be seen and understood.

Bubble carved by supernovae

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 zones in space where stars can form – lie on the bubble’s surface.

“We have calculated that about fifteen supernovae have exploded over millions of years to form the Local Bubble we see today,” said Catherine Zucker, who completed the work while at the CfA.

slow growth

The bubble is not inactive and continues to grow slowly, at about six kilometers per second, but “it has lost most of its thrust and has stabilized in terms of speed,” according to the expert.

The bubble’s expansion rate, 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: models of supernovae, stellar motions, and exquisite new 3D maps of the material surrounding the Local Bubble,” explained another of the authors, Alyssa Goodman of Harvard University.

Coincidence of being in the center

When the first supernovae that created the Local Bubble erupted, “our Sun was a long way from the action,” added co-author João Alves, a professor at the University of Vienna.

However, about five million years ago, the Sun’s path through the galaxy took it right inside the bubble, and it is, “just luckily, almost smack in the middle” of it.

Astronomers first proposed that superbubbles were ubiquitous in the Milky Way nearly fifty years ago, and “now we have proof,” Goodman said.

“Swiss cheese”

The scientist compares the discovery with a Milky Way that resembles a Swiss cheese with many holess, which are ejected by supernovae, and new stars can form in the cheese around holes created by dying stars.

The team now plans to map more interstellar bubbles to get a full 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.

(With information from DWTV)

 
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