The Earth and our solar system as a whole are at the center of a ‘void’ of 1,000 light years surrounded by thousands of young stars, but how did they form?
In an article published this Wednesday in the magazine Nature, astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA) and the Space Telescope Scientific Institute (STScI) in the US, along with European colleagues, reconstruct the evolutionary history of our galactic environment, explaining the events that led over millions of years to the creation of the gigantic bubble where the next stars are born.
The central figure of the article, a interactive 3D animation, confirms that all young stars and star-forming regions within a radius of 500 light-years from Earth are on the surface of this colossal bubble known as Local Bubble. Although its existence has been known for decades, scientists have now been able to see and understand how it originated and its impact on the gas that surrounds it.
14 million years ago, a series of supernovae began to explode and was pushing interstellar gas outward, creating the bubble-shaped structure on whose surface, about 500 light-years away, all young stars form. close.
Thanks to the new data analysis and 3D model, the authors explain that several supernovae they started to explode for the first time 14 million years ago and they were pushing the interstellar gas out, creating the bubble-shaped structure with a surface suitable for star formation.
Today they meet seven molecular clouds or star-forming regions on this surface: Ophiuchus, Pipe or Pipa, Corona Australis, Musca, Chameleon, Lupus and Taurus.
“For the first time we can explain how the formation of nearby stars began”, says the astronomer and co-author. Catherine Zucker, who worked at CfA and now at STScI, and adds: “We estimate that some 15 supernovae they burst over millions of years to form the Local Bubble we see today.”
3D Model of the Local Bubble developed by the authors. / C. Zucker et al./Nature
This oddly shaped blob is not idle and keep growing slowly: “It goes at about 6 kilometers per second,” says Zucker, “however, it has lost most of its momentum and, in terms of speed, has stabilized.”
The bubble’s expansion velocity, as well as the past and present trajectories of young stars forming on its surface, were deduced using data from the Gaia Mission of the European Space Agency (ESA).
Supernova material for new stars
“The elements processed in the supernovae end up in the new stars (mixed with the gas that was close to the supernovae),” another of the authors tells SINC, João Alves, professor at the University of Vienna (Austria). “Also, the material ejected by supernovae plays an important role in the formation of new planets – it’s where iron, gold, etc. of the Earth -, determining, for example, whether they will be rich or poor in water”, adds
Our Sun happens to be in the center of the bubble: it entered about five million years ago and will rise in five more, according to the authors.
About the central position of our Sun in the bubble, the professor indicates that it is purely by chance: “When the first supernova that created the Local Bubble exploded, the Sun was very far from the action, but about five million years ago, the A Our star’s trajectory through the galaxy has taken it right into it, and now it is – fortunately alone – almost at the very center of the bubble.”
“As the bubble is not expanding much (although more supernovas are expected soon, like the star Antares), the Sun should leave the bubble in about another five million years”, explains Alves to SINC, who points to the possibility of our star would have originated on the surface of another bubble before traveling to its current position: “Yes, we have evidence from meteorites in the solar system that the Sun was born close to a supernova,” he says.
Bubbles in the galaxy like Gruyère cheese
The researcher Alyssa Goodman Harvard, CfA and creator of Glue (the data visualization software used in the work) compares the Milky Way to a big Gruyère cheese, where supernovas blast holes and new stars form around it with the ejected material. The study tests this idea, created nearly 50 years ago, when it was already theorized about the ubiquity of superbubbles in our galaxy.
Now the authors plan map more 3D bubbles stars to gain a complete picture of their characteristics and relationships, allowing astronomers to understand the role that dying stars play in the birth of novae, as well as the structure and evolution of galaxies like the Milky Way.
The studies, data, images and interactive videos associated with this research were made available to any interested party through a Network. In addition, the results were also presented and recorded during a Press conference of the American Astronomical Society (AAS).
Reference:
“Star formation near the Sun is driven by the expansion of the local bubble.” Nature, 2022.
Rights: Creative Commons.
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