via Livescience.com, astronomers have discovered a solar "twin" of our own Sun, some 200 light years distant. The star HIP 56948 is located in the Draco constellation in our sky and may be as much as a billion years older than the Sun's 4.6 billion years.
One of the most unique features of our Sun's composition is that it contains a very low level of the element lithium, found in most other stars in far higher concentrations. A spectrostopic analysis of HIP 56948 shows it to have a level of lithium much like that of the Sun.
"The wayward star challenges the idea that our backyard star has a unique composition, as it has a similarly low quantity of the element lithium--a lightweight byproduct of the fusion reactions that power stars...Three other solar twins were previously proposed: 18 Scorpius, HD 98618 and HIP 100963. While similar to the sun in many ways, spectrographic analysis revealed that their lithium contents are dramatically higher. Because of those observations, astronomers wondered if the sun's low amount of lithium was unique. The newfound twin now shows that it isn't."