Just a little late for the New Year celebrations, astronomers have discovered that the Milky Way, our home, is like champagne, full of bubbles.
As it happens, our solar system is passing through the center of one of these bubbles. Fourteen million years ago, according to astronomers, a series of cannon-powered supernova explosions ejected all the gas and dust from an area about 1,000 light-years across, leaving it without the material it needed to create. new generations of stars.
As a result, all the baby stars in our neighborhood can be found stuck on the edges of this bubble. There, the staccato forces of an earlier generation of exploding stars pushed clouds of gas together into forms dense enough to collapse at their own risk if gravity diffused and condensed enough to ignite. , like small stars. Our sun, 4.5 billion years old, passes through this middle of space in a group of old stars.
“This is really an origin story,” Catherine Zucker said in a news release from the Harvard-Smithsonian Center for Astrophysics. “For the first time, we can explain how all the neighboring stars started to form.”
Dr. Zucker, now at the Space Telescope Science Institute in Baltimore, led a team that mapped what they called the Local Bubble in detail. They used data from several sources, notably Gaia, a European spacecraft that has mapped and measured more than a billion stars, to determine the location of clouds of gas and dust.
Last year, a team of scientists led by João Alves, an astrophysicist at the University of Vienna, announced the discovery of the Radcliffe Wave, an undulating string of dust and gas clouds 9,000 light-years long that may be the backbone of our local branch of the galaxy. Part of the wave now appears to be part of our Local Bubble.
The astronomers write the results provide “strong observational support” for a long-standing theory that supernova explosions are important in triggering star formation, perhaps by jostling out clusters of galaxies. Clouds of dust and gas collapsed and began on the long road to fusion luminosity.
Astronomers have long recognized the Local Bubble. Alyssa Goodman, a member of the team also from the Harvard-Smithsonian Center for Astrophysics, says what is new is the observation that all regions of local star formation are located on the surface of the Local Bubble. Previous researchers lacked the tools to map clouds of gas and dust in three dimensions. “Thanks to 3-D dust mapping, we have now done it,” says Dr. Goodman.
According to the team’s calculations, the Local Bubble began 14 million years ago with a large supernova, the first in about 15 years; Big stars die and explode. Their explosive waves swept the area. Therefore, there are no stars younger than 14 million years in the bubble, Dr. Goodman said.
The bubble continues to grow at a rate of about 4 miles per second. However, many supernovas are expected to occur in the near future, like Antares, a red supergiant star near the edge of the bubble that could enter any century, said Dr Alves. “. “So the Local Bubble is not ‘done.'”
With scores of famous star-forming regions perched on the surface of the bubble, the next generation of stars is safely mined.
The team plans to go ahead and map more bubbles in the champagne of our Milky Way. Dr. Goodman said there must be more, because it would be too much of a coincidence for the sun to be eclipsed in the middle of a single sun.
Dr Alves said the sun’s presence in this region was coincidental. Our star strayed into the region just 5 million years ago, long after most of the action, and will exit about 5 million years from now.
The motions of stars are more irregular than is usually depicted, because they are gravitationally collided by other stars, clouds and the like, Dr. Alves said.
“The sun is moving at a speed significantly different from the average speed of stars and gas in the sun’s vicinity,” he noted. This will allow it to catch up and overtake – or be overtaken by the bubble -.
“It’s a revelation,” says Dr. Goodman, “how terrifying the path of the sun really is compared to a simple circle.”
https://www.nytimes.com/2022/01/20/science/milky-way-local-bubble-stars.html New map of the Sun’s local bubbles