Early mixing of gas within giant molecular clouds (the birthplace of stars) mean all stars formed from the same cloud bear identical chemical "tags"; these celestial tags could help us find our Sun's twin.
Stars are composed primarily of hydrogen and helium, but also contain a mixture of other elements. By carefully analyzing wavelengths of light coming from stars researchers can determine the abundance of each trace element, the University of California High-Performance Astro Computing Center reported.
"The pattern of abundances is like a DNA fingerprint, where all the members of a family share a common set of genes," said Mark Krumholz, associate professor of astronomy and astrophysics at University of California, Santa Cruz (UCSC).
Families of stars do not always stick together, meaning these measurements could prove to be immensely useful in determining the origin of these objects. Through this technique researchers could determine if stars at opposite sides of the galaxy were actually born from the same star cluster billions of years ago; but there is one problem.
"Although stars that are part of the same long-lived star cluster today are chemically identical, we had no good reason to think that such family resemblance would hold true of stars that were born together but then dispersed immediately," Krumholz said. "The underlying problem was that we didn't really know why stars are chemically homogeneous."
To solve this problem the researchers simulated two streams of interstellar gas that came together to form a cloud that collapsed under its own gravity and created a cluster of stars. They added tracer dyes to the two streams, allowing them to watch how the gas mixed during this process. They put red dye in one stream and purple in the other, by the time the gases mixed the cloud was purple.
"The simulation revealed exactly why stars that are born together end up having the same trace element abundances: as the cloud that forms them is assembled, it gets thoroughly mixed very fast," Krumholz said. "This was actually a surprise: I didn't expect the turbulence to be as violent as it was, and so I didn't expect the mixing to be as rapid or efficient. I thought we'd get some blue stars and some red stars, instead of getting all purple stars."
The finding helps to back up the idea of chemical tagging.
"This is good news for prospects for finding the Sun's long-lost siblings," Krumholz said.
