By Prarthana Mitra
The sun is perhaps the most significant planetary body, helping determine the very nature and structure of planets in the solar system. However, is our sun the only one in our galaxy, or the unending universe? Scientists believe that our sun may just have far-flung siblings located many light years away.
Since star births generally occur in clusters of hundreds of thousands, scientists believe that the stars that were born alongside the sun—its “stellar siblings—were likely pulled apart, and thus spread across the galaxy. However, scientists hope to find the sun’s stellar siblings by tracking its emissions.
Here’s what happened
Measuring a star’s emission spectrum to determine its composition, is no longer as cumbersome or time-consuming as it used to be. In an extraordinary feat, the Global Archaeology Survey, also known as GALAH, has recorded the composition of 342,000 stars over 1,000 hours, in order to study the origin of our brightest star.
With the help of the new HERMES spectrograph attached to the Anglo-Australian Telescope, the GALAH aims to detect “original star clusters in the galaxy, including the Sun’s birth cluster and solar siblings,” said Dr Gayandhi De Silva of the University of Sydney.
Speaking to IFLScience, he also said the recent sample includes a third of the total stellar-database, estimated to measure a million of the brightest stars. The emission data on over 340,000 stars—mostly above the Southern Hemisphere—will certainly provide a great head start to astronomers, but the quest for the sun’s siblings will have to wait until a northern hemisphere telescope joins the search.
“No other survey has been able to measure as many elements for as many stars as GALAH,” said De Silva, after announcing the release of the first batch of data yesterday, followed by eleven papers in the journals Astronomy & Astrophysics and the Monthly Notices of the Royal Astronomical Society.
Why you should care
Out of the trillions of stars in our galaxy, there are many that were born alongside the sun, from the same matter, elements and energy. Stars are formed not in isolation but in clusters, and these clusters don’t remain spatially or compositionally intact over the course of their life—they are often pulled apart by gravitational dynamics.
In such cases, the only way to discover the sun’s siblings would be by studying their composition. Stars born from the same gas cloud have a similar chemical composition, since the star formation process turbulently mixes gasses within the cloud. In other words, scientists may be able to find clues pointing to a very close pattern of star formation between different stars, which lead them to discovering the sun’s stellar siblings.
At the moment, we know very little about our sun’s past and even less about how it may evolve in the future. However, in order to determine the longevity, and subsequent trajectory of our ageing sun, it is imperative to locate the origin and motion of stellar and solar siblings. So the next time you scan a starry sky on a clear night, it shouldn’t come as a surprise if one of them is just another sun.
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