The solar system lies inside a structure called the Local Bubble that is some 1000 light years across – and a map of its surface shows it is the site of star formation
12 January 2022
The star-forming regions that surround our solar system have been mapped for the first time.
These regions appear to lie on a deformed surface 1000 light years across, called the Local Bubble. The bubble’s interior, which is where the solar system is found, is mostly empty space. But its shell comprises cold gas and dust, left over from exploding stars. New stars are now forming from this material.
We have known about the existence of the Local Bubble – and about the star-forming regions nearest to the solar system – for decades. But Catherine Zucker at Harvard University and her colleagues have now made a clear connection between the two.
They did so using data from the European Space Agency’s Gaia satellite, which maps the positions, distances and motions of stars with high precision. This allowed them to construct a three-dimensional map of the different star-forming regions. The map also used Gaia’s motion data to chart how the Local Bubble has evolved over time and created the star-forming regions.
“We’ve discovered a common origin for all nearby star formation,” says Zucker. “We can essentially explain how every single star-forming region within 500 light years from our sun began.”
When some stars reach the end of their life, they trigger a powerful explosion called a supernova. Our Local Bubble appears to have formed when several supernova shock waves swept gas and dust through space, forming the Local Bubble’s dense shell. With time, the shell began to form a series of molecular clouds, which are the birthplaces of new stars.
“This result argues strongly for the case that star formation triggered by expanding shells is probably more important than we thought before,” says Martin Krause at the University of Hertfordshire, UK.
There is some uncertainty over the exact shape of the bubble: we don’t know whether the top and bottom, with respect to the Milky Way’s disc, are open or closed, for instance. But Zucker and her team are confident about the shape of the bubble where star-forming regions lie, within a margin of error.
Journal reference: Nature, DOI: 10.1038/s41586-021-04286-5
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