CheeseGrater 1.104 -- http://www.jwz.org/cheesegrater/ http://antwrp.gsfc.nasa.gov/apod/ Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. en webmaster@jwz.org Sun, 18 May 2008 06:00:01 GMT Sun, 18 May 2008 06:00:01 GMT http://www.nasa.gov/images/hotnasa.gif 78 68 http://antwrp.gsfc.nasa.gov/apod/ http://antwrp.gsfc.nasa.gov/apod/ap080518.html <DIV ALIGN=CENTER><a href="http://antwrp.gsfc.nasa.gov/apod/image/0805/nsmerger_heasarc_big.jpg"> <IMG SRC="http://antwrp.gsfc.nasa.gov/apod/image/0805/nsmerger_heasarc.jpg" alt="See Explanation. Clicking on the picture will download the highest resolution version available."></a> </DIV> <DIV STYLE="max-width:40em"><P> <P> <b> On the Origin of Gold </b> <br> <b> Illustration Credit : </b> <a href="http://svs.gsfc.nasa.gov/search/Animator/DanaBerry.html">Dana Berry</a>, <a href="http://www.nasa.gov/">NASA</a> <P> <p> <b> Explanation: </b> Where did the <a href="http://en.wikipedia.org/wiki/Gold#History">gold</a> in your jewelry originate? <a href="http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1999ApJ...525L.121F" >No one is completely sure</a>. The relative average abundance in our <a href="http://www.nineplanets.org/overview.html" >Solar System</a> appears higher than can be made in the <a href="http://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis" >early universe</a>, in <a href="http://zebu.uoregon.edu/textbook/energygen.html" >stars</a>, and even in typical <a href="http://heasarc.gsfc.nasa.gov/docs/snr.html" >supernova explosions</a>. Some <a href="http://arxiv.org/abs/astro-ph/0012046">astronomers have recently suggested</a> that neutron-rich heavy <a href="http://periodic.lanl.gov/">elements</a> such as <a href="http://periodic.lanl.gov/elements/79.html" >gold</a> might be most easily <a href="http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1997LPI....28..947M" >made</a> in rare <a href="http://en.wikipedia.org/wiki/Neutron">neutron</a>-rich explosions such as the <a href="http://dast.nlanr.net/OH/Jn-sc98/sld001.htm" >collision</a> of <a href="http://imagine.gsfc.nasa.gov/docs/science/know_l1/pulsars.html" >neutron stars</a>. <a href= "http://heasarc.gsfc.nasa.gov/docs/objects/heapow/archive/transients/grb050509b_swift.html" >Pictured above</a> is an artist's illustration depicting two <a href="http://www.astro.umd.edu/~miller/nstar.html" >neutron stars</a> spiraling in toward each other, just before they <a href="http://www.youtube.com/watch?v=HfDDI_SCarw>collide</a>. Since <a href="http://terpsichore.stsci.edu/~summers/viz/scviz/ruffert.html" >neutron star collisions</a> are also suggested as the origin of <a href="http://imagine.gsfc.nasa.gov/docs/science/know_l1/short_grbs.html" >short</a> <a href="http://antwrp.gsfc.nasa.gov/apod/ap051017.html">duration</a> <a href="http://antwrp.gsfc.nasa.gov/apod/ap980507.html">gamma-ray bursts</a>, it is possible that you already own a souvenir from one of the most <a href="http://antwrp.gsfc.nasa.gov/apod/ap020405.html">powerful explosions</a> in the universe. <p> <P> <script type="text/javascript"> digg_url = 'http://apod.nasa.gov/apod/ap080518.html'; digg_skin = 'compact'; </script> <script src="http://digg.com/tools/diggthis.js" type="text/javascript"></script> </DIV>