Gold!

Gold.

There has been a lot of it about in London recently.

Chris Hoy, Gold medals

Gold! (BBC)

Thousands have pushed themselves to their absolute limits in order to have some hung around their necks.

Millions more have watched in awe as they did so.

An element so rare that despite thousands of years of extraction and a range of ingenious methods humans have only gathered 165,000 tonnes of the stuff.

While many have said that its value is mainly aesthetic and down its scarcity, gold has a range of uses and is in tiny amounts scattered around you in electronic devises as well as jewellery.

Where’s the Astronomy?

Perhaps the most remarkable fact about Gold is it’s origin.  I’s rarity points to something special. This isn’t an element that comes together easily in the great cosmic chemistry set of the stars.

Around every Olympic champions neck is a fragment of evidence to an ancient, cataclysmic event.

A supernova.

Tycho Supernova

Supernova (NASA)

The Gold around your finger, in your mobile phone, perhaps in your mouth as a filling or in your expensive cocktail, is the work of a gigantic dying star.  A star no human ever laid eyes on, that died so dramatically and with such high temperatures and pressures that it made its way through the periodic table in its last dying seconds.

M1 Crab Nebula

M1 Supernova Remnant (Author)

Our own star is currently working away at the bottom of the list of 92 natural elements.  Every second over 600 million tons of Hydrogen, the simplest element, is fused in the core of the Sun into the next on Mendeleev’s famous list, Helium.  Like plankton working away at the bottom of the food chain this start of the nuclear-synthesis chain is the easiest but most essential.  Without this step stars don’t shine, energy isn’t released and the universe would be mainly dark, cold and hydrogen.

Our Sun will not produce gold though.  It will do well, towards the end of its life the Sun will run out of Hydrogen and begin to synthesise Oxygen and Carbon.  When you look at a planetary nebula that is what spectroscopy tells us those pretty clouds are made of.  The Ring Nebula, The Dumb Bell Nebula, The Cats Eye Nebula – Carbon, Oxygen, Helium, Hydrogen all drifting into space leaving the fading ember of a White Dwarf.

For our Athletes to receive gold and indeed silver then something a little different is required.  Stars far larger than our Sun will not go quietly and will bring to the universe the essential ingredients that go to make Earth, Olympic champions and the medals they compete for.

In its dying years a very massive star will have produced elements all the way to silicon and then they start to fuse this into Iron.  We now have many of the ingredients, layer on layer of elements, to eventually create a Mo Farah or Laura Trott but to complete the stellar larder we need these stars to destroy themselves.

When it happens Star death is fast.  It takes a few seconds to produce the final elements. Usain Bolt took 9.63 seconds to win the 100 metres, across the universe 288 supernova occurred between the b of the bang and that famous lightning bolt celebration; producing gold all across the universe.

Usain Bolt, 100M, London 2012

288 Supernova. (BBC)

So here we are, the result of star death, coveting, worshipping and competing for one of the rarest results of stellar nuclear synthesis.

But the astronomy-gold story isn’t complete.  Earth was formed from the debris that contained Gold.  But the Gold presented to the winners in Stratford isn’t really from Earth.  Gold is heavy.  Earth’s Gold is locked deep inside it’s core, gravitationally differentiated away from the surface during our planets evolution.  The gold we find on our rocky surface arrived later, locked in rocks and dust that fell to Earth, probably during the late heavy bombardment- the event that so scared our moon.

If you are watching the Persieds at the moment, then in a search for Olympic Gold, you are looking in the right direction.

Perseid Meteor 2012

Gold from the sky (Guardian)

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About astronomersden

Daddy, Hubby, Teacher and when ever I get the chance Astronomer.
This entry was posted in Astronomy, Life, Sun, Supernova, The Astronomer's Den and tagged , , , , , , , , , . Bookmark the permalink.

One Response to Gold!

  1. Active Astro says:

    Your best yet I think. A marvellous read. Always something to learn and always tied in with something current.

    Thanks again for a wonderful and educational article!

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