A comparatively dust-free region, which the sun has traversed for millions of years, was formed about 14 million years ago by several stellar explosions that subsequently led to the formation of thousands of stars. This has now been confirmed by astronomers led by Catherine Zucker from the Harvard Smithsonian Center for Astrophysics.
Using data from the revolutionary ESA space telescope, they determined that the so-called local bubble is expanding as a result of more than a dozen supernovae and is responsible for the formation of all young stars in the cosmic neighborhood. All of the star-forming regions near the Sun are right on the edge of this bubble.
The end of one star as the beginning of the next
It has been known for decades that the sun is located in the so-called local bubble, which is up to 1000 light-years across. It was also assumed that it was caused by exploding stars that ejected material. But just how central the bubble is to the formation of stars in the Sun’s immediate vicinity has only now been confirmed.
A total of seven star-forming regions lie at the edge of this bubble, Zucker and her team investigated. There, the material encounters interstellar dust, messes it up and thus initiates the formation of stars. The bubble is now no longer spreading as quickly as it did at the beginning; the researchers have come up with a propagation speed of around 23,000 km/h.
With their work, they wrote, so to speak, the history of the origins of the cosmic neighborhood of the sun, says Zucker. Who wants, can view their 3D Local Bubble maps on the Internet. Like her and her research group now in the specialist magazine Nature to explain, they have not only determined that the young stars are all at the edge of the Local Bubble, but thanks to Gaia they even know that they are mostly moving outwards as well. For years, the space telescope has been creating an increasingly precise celestial atlas that not only includes the positions, but also the movements of billions of stars. The team’s findings are not only based on this data, but also on new models of supernovae and particularly good three-dimensional maps of the material outside the local bubble.
The team also reconstructed the path of the sun through the gigantic bubble: When the supernovae ignited, our home star was still a long way away. Then, about five million years ago, she entered the expanding bubble and made her way straight to the center, where she is now. Statistically, it is very unlikely that the Sun would be in the center of such a bubble right now if they were rare in the Milky Way. Instead, they are likely to be fairly common and play a crucial role in star formation. The team wants to explore this further and map other bubbles to do so. They also want to find out what happens where these bubbles meet.