In an article published this Wednesday in the journal Nature , a team of astronomers from the Harvard-Smithsonian Center for Astrophysics (CfA) and the Space Telescope Science Institute (STScI) in the US, together with European researchers, has shown that the region of cold gas and stellar dust called the Local Bubble, is responsible for the formation of all the nearby young stars in our solar system (including our Sun).
Using a 3D model , experts have shown how a chain of events that began 14 million years ago with a set of powerful supernovae led to the creation of the great Local Bubble, responsible for the formation of all the young stars 500 light years from the Sun.
Thus, the star formation process occurs over the entire surface of the bubble. First, superbubbles like this were theorized to be ubiquitous in our galaxy nearly 50 years ago. Now, “we have proof, and what are the chances that we are right in the middle of one of these things? ” asks Alyssa Goodman, an astronomer at Harvard University and the Harvard & Smithsonian Center for Astrophysics, co-author of the study.
“Statistically, it is highly unlikely that the Sun would be centered on a giant bubble if such bubbles were rare in our Milky Way . The Milky Way is a lot like Swiss cheese with holes, where supernovae blow up the holes in the cheese, and new stars can form in the cheese around the holes created by dying stars.”
The study reveals that Earth and all stars and star-forming regions within 500 light-years of the planet reside on the surface of this bubble.
Learning more about how Earth came to be inside the Local Bubble could be another definitive step in better understanding our galaxy. “Essentially, we have a front row seat to the star formation that is happening on the surface around us,” says Catherine Zucker, leader of the work.
In their study, the scientists sought to create a map of the major landmarks in the solar system’s galactic neighborhood using data from the most recent release of Gaia , the ongoing project to map the positions and movements of the stars in our galaxy as accurately as possible; all objects within 200 parsecs, about 650 light-years, of the Sun. They analyzed the 3D positions, shapes, and motions of dense gases and young stars about 650 light-years from the Sun. They mapped three dimensions of space, three dimensions of motion, and one dimension of time.
Analysis of the motions of young stars helped scientists piece together the chain of events behind the creation and growth of the Local Bubble. They found that these stars were mostly traveling in straight lines from the surface of the bubble , which suggested that they were moving because the bubble was expanding over time.
They found that the history of the Local Bubble began about 14.4 million years ago, first with a period of star birth, followed by short-lived supernovae of massive stars. “We have calculated that about 15 supernovae have gone off over millions of years to form the local bubble we see today,” explains Zucker.
It currently has a radius of about 538 light-years and continues to expand outward, albeit slowly, at 6.7 kilometers per second.
Referencia: Catherine Zucker, Star formation near the Sun is driven by expansion of the Local Bubble, Nature (2022). DOI: 10.1038/s41586-021-04286-5. www.nature.com/articles/s41586-021-04286-5
