Local Bubble: Huge gas structure that contains the solar system mapped for first time

The solar system lies inside a structure called the Local Bubble some 1000 light years across – and a map of its surface shows it is the site of star formation


12 January 2022

Artist's illustration of the Local Bubble

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

Leah Hustak (STScI)

The star-forming regions that surround our solar system have been mapped out 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 dead stars exploding. New stars are now forming from this material.

We’ve 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 Zucker and her team 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 shockwaves swept gas and dust through space, forming the Local Bubble’s dense shell. With time, that dense shell began to form a series of ‘molecular clouds’, which are the birth places 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, who was not involved in the research.

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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