Wednesday, November 16, 2011

Galactic 'fossils' in Milky Way reveal how our galaxy was spray-painted with gold dust by ancient supernovas - 15th Nov 2011

On the outer edges of the Milky Way are stars that astronomers study like galactic fossils - ancient stars formed in the youngest years of our galaxy.

The puzzle for scientists is why these stars are so rich in gold, platinum and uranium - heavy metals that are usually only formed much later in the history of galaxies.

Now scientists think they've solved where the galactic bling that fringes our galaxy came from - and from it, have gained an insight into the prehistory of our galaxy.

When stars explode, the resultant gas clouds condense back together, forming new stars - and each 'generation' tends to be richer in heavier, more complex elements such as gold, platinum and uranium.

Stars formed in the early history of galaxies should be low on such heavy-metal riches - but stars in our galaxy show up a surprising amount of gold and other heavy metals.

'In the outer parts of the Milky Way there are old ‘stellar fossils’ from our own galaxy’s childhood. These old stars lie in a halo above and below the galaxy’s flat disc. In a small percentage -of these primitive stars, you find abnormal quantities of the heaviest elements,' explains Terese Hansen, who is an astrophysicist in the research group Astrophysics and Planetary Science at the Niels Bohr Institute at the University of Copenhagen. Read More