After the Big Bang, the Universe consisted of mostly hydrogen, some helium and a little lithium, so the first stars to form would have contained only these elements. It was the first generation of stars that converted these lighter elements into heavier ones like carbon, phosphorous, iron and lead - collectively known to astronomers as metals. When those stars exploded they "polluted" the cosmos with these heavier elements, which themselves went into a later generation of stars - like our Sun. The existence of stars with zero or very low metal content has been predicted for decades, but none has ever been found, leading some to suspect they never existed - until the discovery of HE0107-5240. The star was spotted in the outer reaches of our galaxy by Norbert Christlieb, at the University of Hamburg in Germany, and colleagues. It lies in the direction of the southern constellation Phoenix, at a distance of about 36,000 light-years. The star has just 1/200,000th of the metal content of our Sun. Recent cosmological studies show that the Big Bang occurred 13.7 billion years ago. The metal-poor star HE 1523 formed in our Milky Way galaxy soon afterward (cosmologically speaking: 13.2 billion years ago)
How old are the oldest stars" astronomers recently measured the age of a star located in our Galaxy. The star, a real fossil, is found to be 13.2 billion years old, not very far from the 13.7 billion years age of the Universe. The star, HE 1523-0901, was clearly born at the dawn of time.

Amazing photos from http://www.eso.org/public/