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Long-lost stellar siblings could soon be reunited 鈥� a finding that could help galactic archaeologists piece together the Milky Way鈥檚 history.
Stars form within dense cocoons of dust and gas. But as a galaxy evolves, these clouds break apart and their stars are scattered. A star鈥檚 home address would be lost to time, if it wasn鈥檛 for the fact that each molecular cloud has a unique mix of elements, which is passed on to the stars born there says David Hogg of New York University.
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Like a DNA fingerprint, these distinct chemical signatures 鈥� called spectra 鈥� could help astronomers identify siblings billions of years after they left home. They could even help astronomers find the sun鈥檚 earliest quarters.
Although astronomers have long speculated that this technique could work, there is a problem: a star鈥檚 spectrum can look different depending on its mass and temperature. Hot stars, for example, tend to burn bluer than their colder counterparts, shifting the shape of their spectra so that they emit more light at shorter wavelengths.
This means that stars born in the same cloud could end up with wildly different spectra, despite identical chemical abundances. So astronomers need precise models that show what the spectrum of a star with a specific chemical fingerprint looks like at any mass or temperature.
Unbound stars
Previous studies used theoretical models to do this, but Hogg and his colleagues used the spectra from 10,000 stars to build a data-driven model. This then helped them estimate the composition of 100,000 stars, which revealed known stellar clusters and even a collection of older stars that aren鈥檛 bound together.
The team plans to pinpoint the velocity of each of the unbound stars to see if they are running away from the same ancestral home 鈥� proving that the technique could unleash layers of history.
鈥淗idden in all the stars is how the whole galaxy formed,鈥� says Alice Quillen of the University of Rochester in New York state, who wasn鈥檛 involved in the study. This technique unlocks that secret, providing valuable information about a star鈥檚 origin 鈥� perhaps outside the Milky Way itself 鈥� and its chaotic voyage since.
鈥淭here鈥檚 a model you could build in principle of all of those different processes,鈥� says Hogg. 鈥淎nd we would love that.鈥�
Journal reference: arxiv.org/abs/1601.05413v1
