Our sun and a number of sun-like “solar twins” may have migrated away from the core of the Milky Way galaxy together, potentially making the solar system more hospitable to life as we know it, new research finds.
Around The Milky Way are solar twins, stars that physically look very similar the sun. By analyzing solar twins, astronomers hope they can learn more about the sun’s history.
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“We found many more solar twins with ages more similar to the Sun than I expected,” researcher Daisuke Taniguchi, an astronomer at Tokyo Metropolitan University, told Space.com.
By analyzing the sizes, temperatures and compositions of these nearby solar twins, Taniguchi, Takuji Tsujimoto of the National Astronomical Observatory of Japan and their colleagues were able to estimate the age of the stars. Looking at the age range, they noticed a broad peak for 1,551 stars that are about four billion to six billion years old. (This population includes our Sun, which is about 4.6 billion years old.)
The discovery that the Sun and many of these solar twins are of the same age and are roughly the same distance from the center of the galaxy suggests that the Sun is not in its current position by accident. Previous research suggested that, based on the Sun’s “metallicity” — its levels of elements heavier than hydrogen and helium — it was born more than 10,000 light-years closer to the galaxy’s inner regions, which are higher in metals than the part of the galaxy where the Sun now resides.
The new results suggest that the Sun may be part of a larger population of stars that migrated outward from the galactic core at about the same time – four billion to six billion years ago.
“We learn about the Sun’s past orbit indirectly by studying other similar stars,” Taniguchi said.
This discovery not only sheds light on our nature the solar systembut the development of galaxy himself. At the center of the Milky Way is a giant rotating rod-like structure that would now make it difficult for such a mass migration of stars to take place. However, these new findings reveal details about when this “co-rotation bar” formed. In fact, the birth of this huge sweeper may initially have concentrated gas to help trigger star formation and then propel stars outward, the researchers suggested.
These new findings may also shed light on what conditions may have helped life on earth to develop, the researchers said.
“The inner regions of the Milky Way are believed to be more hostile environments for life, with energetic events such as supernova explosions occurring more frequently,” Taniguchi said. If the Sun migrated outward relatively soon after birth, “the solar system may have spent most of its history in the quieter outer disk. In other words, the Sun cannot have arrived in a habitable environment purely by chance, but rather as a consequence of the formation of the galactic bar.”
The researchers aim to expand their work to cover a larger release of data from Gaia planned for December. They also plan to take a closer look at the composition of these solar twins, which “could help identify stars that were born at the same place and time as the sun — that is, true twins,” Taniguchi said.
The researchers detailed their findings on 12 March i two studies in the journal Astronomy & Astrophysics.
