You might think that all stars are born, live, and die in the same place, but it turns out that’s not always the case.
Some stars move around and end up in places where you wouldn’t expect to find them.
A team of scientists from the University of Sheffield and Imperial College London has discovered an example of this stellar oddity – an old ‘retired’ star hanging out in a neighborhood of young, planet-forming stars.
These scientists were able to make this discovery thanks to a space satellite called Gaia. Gaia’s job is to map the positions of billions of stars in our galaxy.
It’s like Google Maps for the Milky Way! The cost of this project is quite impressive, about 740 million Euros, but its results are spectacular.
The most recent set of data from Gaia, called ‘Data Release 3’, is even better than before. It allows the team to locate stars that are not in their usual spots.
These wandering stars, or ‘interlopers’, are stars that did not form where they are currently located, but have somehow moved into the area.
In the past, the team has found young interloping stars, but this time they’ve found an old, evolved star, known as an AGB (asymptotic giant branch), in a region where new stars are forming.
This is very unusual, because people used to think that old and young stars lived in completely separate parts of the galaxy.
The interesting thing about these AGB stars is that they produce large amounts of two chemical elements: Aluminum-26 and Iron-60. These elements are radioactively unstable, meaning they slowly break down and give off heat.
It turns out that these two elements were delivered to our young solar system when the Earth was forming. The heat they released as they decayed could have warmed the early Earth.
In fact, the heat from Aluminum-26 and Iron-60 might have even helped kick-start plate tectonics on our planet. Plate tectonics is the process where large pieces of the Earth’s crust move around, causing earthquakes and volcanic eruptions.
This process is also important for maintaining a breathable atmosphere on Earth.
The research team worked out how much Aluminum-26 and Iron-60 from the AGB could be captured by a star like our sun when it was forming its planets.
Dr. Richard Parker from the University of Sheffield, who led the study, said, “Until now, researchers have been skeptical that these old, evolved stars could ever meet young stars that are forming planets.
By showing that AGB stars can meet young planetary systems, we have shown that other sources of Aluminum-26 and Iron-60, such as the winds and supernovae of very massive stars, may not be required to explain the origin of these chemical elements in our solar system.”
The team’s next mission is to look for other old stars in young star-forming regions to see how common these retired wanderers are.
This could help us understand even more about the life journey of stars and the early history of our own planet.
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Source: University of Sheffield.
