For decades, it’s been known that the Sun lies within a cavity of low-density, high-temperature plasma surrounded by a shell of cold, neutral gas and dust, or the “Local Bubble” as it’s called.
But the exact shape and extent of this shell, and its relationship to the nearby star formation have remained uncertain. However, astronomers at the Center for Astrophysics, Harvard & Smithsonian (CfA) and the Space Telescope Science Institute (STScI) have made headway in reporting an analysis of the three-dimensional positions, shapes and motions of dense gas and young stars within 200 pc of the Sun in a new study published in Nature.
By using new spatial and dynamical constraints, they’ve found that all young stars and star-forming regions in the solar vicinity lie on the surface of the Local Bubble.
“The spacetime animation shows how a series of supernovae that first went off 14 million years ago, pushed interstellar gas outwards, creating a bubble-like structure with a surface that’s ripe for star formation,” Space Telescope Science Institute reports.
Astronomer and data visualization expert Catherine Zucker said: “We’ve calculated that about 15 supernovae have gone off over millions of years to form the Local Bubble that we see today… This is really an origin story; for the first time we can explain how all nearby star formation began.”
The astronomers went on to note that the oddly-shaped bubble is not dormant and continues to slowly grow. “It’s coasting along at about 4 miles per second,” Zucker adds. “It has lost most of its oomph though and has pretty much plateaued in terms of speed.”
“When the first supernovae that created the Local Bubble went off, our Sun was far away from the action,” co-author João Alves, a professor at the University of Vienna maintains. “But about five million years ago, the Sun’s path through the galaxy took it right into the bubble, and now the Sun sits — just by luck — almost right in the bubble’s center.”
Today, as humans glance out into space from near the Sun, they have a front row seat to the process of star formation occurring around on the bubble’s surface.
Watch it here:
Picture: Leah Hustak (STScI)