Sneden's Star

BPS CS22892 -052 ( Snedens star) is an old Population II stars in the halo of the Milky Way. It belongs to the rare class of ultra- metal - poor stars ( metallicity [Fe / H] = -3.1 ), and in turn to the rare subclass with an overabundance of r-process elements.

He was discovered by Tim C. Beers and employees with the Curtis Schmidt telescope at Cerro Tololo Inter- American Observatory in Chile. Detailed high-resolution spectroscopic studies since about 1995 ( with Chris Sneden of the University of Texas at Austin as the leading observer ) allowed the determination of the abundances of 53 elements in this star ( only on the sun could be measured).

All abundances for elements heavier than barium ( Z = 56 ) show the pattern of the elements formed by the r-process in the solar system. By comparing the observed in the star abundances of a stable element such as europium (Z = 63) and a radioactive such as thorium (Z = 90) with calculated abundances of these elements in a type II supernova explosion (as of the groups of Karl -Ludwig Kratz were carried out in Mainz and Friedrich -Karl Thielemann in Basel) gives an age of 13 billion years for this star, so the was only a little later than the Big Bang. Corresponding age determined for other ultra - metal - poor stars as CS31082 - 001 or BD 17 ° 3248.