INTERNATIONAL RESEARCH TEAM USING HUBBLE TELESCOPE DISCOVERS GOLD, PLATINUM IN 14-BILLION-YEAR-OLD STAR EMBARGOED FOR RELEASE 9:20 A.M. EST JAN. 10, 2002 By Debra Levy Martinelli University of Oklahoma Public Affairs WASHINGTON - An international research team, one of the leaders of which is a University of Oklahoma scientist, announced today the first confirmed detection of gold, platinum, silver and the radioactive element thorium in an old star in the Milky Way galaxy. Using the Hubble Space Telescope, the space observatory that views space from Earth's orbit, the team detected the elements in a 14-billion-year-old star located in the halo regions of our Milky Way galaxy known as BD +17 3248. The research team, which reported its discovery at the bi-annual meeting of the American Astronomical Society in Washington, is composed of John Cowan of the University of Oklahoma; Christopher Sneden and Inese Ivans of the University of Texas; Scott Burles of the Massachusetts Institute of Technology; Timothy Beers of Michigan State University; James Truran of the University of Chicago; James Lawler of the University of Wisconsin; Francesca Primas of the European Southern Observatory, Germany; George Fuller of the University of California at San Diego; and Karl-Ludwig Kratz and Bernd Pfeiffer of the University of Mainz, Germany. Cowan said the discovery is significant because elements such as gold and platinum could not have been produced internally in BD +17 3248. "They were most likely formed earlier in massive stellar explosions known as supernovae," he said. "During these explosions, which destroy the star, heavy isotopes are produced in a synthesis known as the rapid neutron-capture process. The presence in BD + 17 3248 of neutron-capture elements such as gold and platinum suggests a generation long since gone of stars and supernovae at the earliest times in the history of the Milky Way galaxy." Cowan said that, assuming a uniform distribution throughout this star, at current values the total gold in BD +17 3248 would be equivalent to approximately 7 billion trillion dollars. Sneden added that, while every star probably has a similar amount of gold, it has actually been observed in this one. "This is the first gold in the galaxy," said Beers, another member of the research team. BD +17 3248 is approximately 2,500 light years from the earth. Although Cowan said the star and others like it were formed during the very early history of the galaxy, he and his colleagues were able to put the age of the star at approximately 13.8 billion years. "While the age has an uncertainty of approximately 4 billion years, our observations and theoretical analysis indicate that the star is likely one of the oldest in our galaxy and, consequently, the universe," he said. In addition to the discovery of gold and platinum, Cowan and his colleagues also detected in the star the presence of silver as well as thorium and possibly uranium. These additional observations were made using the 10-meter Keck telescope, located in Mauna Kea, Hawaii, which is one of the largest ground-based telescopes in the world. Cowan said that the different elements were identified with different telescopes because some elements have atomic transitions in the ultraviolet part of the spectrum while others have atomic transitions in the visual part of the spectrum. "Elements such as gold and platinum have atomic transitions in the ultraviolet part of the spectrum that is mostly blocked by the atmosphere. Therefore, the Hubble Space Telescope is needed to identify the presence of those elements in the stars," Cowan said. "Silver, on the other hand, has atomic transitions in the visual part of the spectrum that is visible from the ground. "But the transitions are very weak in these stars and thus require very large telescopes like the Keck for these elements to be identified with some confidence. He said that finding silver in BD +17 3248 further supports the detection of gold and platinum with the Hubble Space Telescope. "The abundance of silver is lower than what might have been predicted, based upon the gold and platinum abundances, which suggests somewhat different conditions for the formation of silver than for gold and platinum," he said. Beers has been conducting searches for such ancient stars in the halo of the galaxy for 20 years. "The discovery of gold, platinum and other interesting elements in BD +17 3248 reaffirms our picture that the story of the creation of the elements is written in the atmosphere of these stars," he said. "As observations such as these are carried out, we are learning how to read this exciting tale." The team's research, which was funded by the National Aeronautical and Space Administration, National Science Foundation, Department of Energy, and Germany's Federal Ministry for Education and Research, was conducted over the past two years. The scientists are conducting further observations and theoretical work to better understand the different astrophysical formation histories for gold, platinum and silver as well as the radioactive elements they have discovered. For more information about the discoveries, contact Cowan at (405) 833-5883 or cowan@mail.nhn.ou.edu ; Sneden at (512) 471-1349 or chris@verdi.as.utexas.edu ; Beers at ________________________________________; or visit . For more information about the University of Oklahoma, contact Jerri Culpepper, coordinator of news and publications, Division of Public Affairs at (405) 325-1701 or jculpepper@ou.edu . ### CUTLINES (Insert above graphs) Observed HST-STIS and synthetic (computed) spectra in the region surrounding the gold spectral line at a wavelength of 2675.94 Angstroms. (One Angstrom = 1/100 millionth of a centimeter). (Insert below graphs) (Top) The observed spectrum of BD +17 3248, shown in blue, is compared to that of another old halo star in our Galaxy known as HD 122563, shown in red. The atomic gold spectral line is seen in BD +17 3248, but not in HD 122563. This detection could only be made using space telescopes such as the Hubble Space Telescope. (Bottom) The observed BD +17 3248 spectrum, shown in blue dots, is compared to four synthetic spectra to determine the abundance of gold. The computed values, shown in order of increasing abundance of gold by dotted, short-dashed, solid, and long-dashed lines computed for these abundances are: log epsilon (Au) = -infinity, -0.80, -0.30, +0.2. The best fit is seen to be for log epsilon = -0.3, which indicates that gold in this star is less than a trillion times as abundant as hydrogen. ============================================================================== Links to figures can be found at http://www.nhn.ou.edu/~cowan/press/