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a star turns inside out presented by

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science at nasa

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in the immortal words of carl sagan we

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are star stuff

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what he meant is the key elements of

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life were forged in the hearts of stars

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the iron that turns our blood red the

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oxygen that fills our lungs the carbon

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that gives infinite variety to organic

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compounds they were all cooked up in a

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stellar inferno billions of years ago

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so when researchers recently got a look

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at a star turned inside out they knew

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they were looking at the stuff of life

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itself

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the story begins just after the big bang

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13.7 billion years ago

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according to modern cosmology the

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newborn universe was made entirely of

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the three simplest atoms hydrogen helium

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and small amounts of lithium

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the cosmos was devoid of stars and very

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likely devoid of life as well

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a quick glance around the room is proof

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that times have changed light elements

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that filled the early universe are rare

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on earth while our planet and we

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ourselves consist mainly of heavier

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stuff like oxygen and carbon which we're

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missing at the dawn of cosmic history

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the difference is star formation

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a little more than 13 billion years ago

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the first stars collapsed from clouds of

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hydrogen and helium

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as gravity drew the gas inward

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temperatures reached levels that

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triggered nuclear fusion the same

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process that powers our sun today

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in a stellar fusion reactor hydrogen and

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helium are smashed together to build up

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heavier elements such as carbon nitrogen

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oxygen and iron

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since then heavy elements have been

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forming in stars throughout the universe

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supernova explosions presumably did the

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rest flinging their contents far and

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wide seeding galaxies with the atomic

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building blocks of life

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recent data from nasa's chandra x-ray

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observatory provide dramatic

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confirmation for this idea

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researchers una huang of the goddard

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space flight center and john lamming of

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the naval research laboratory used

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chandra to map elements in the debris of

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a supernova known as cassiopeia a

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cassay for short

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cassay is located about 11 000 light

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years from earth the original star a

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behemoth at least 15 times as massive as

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the sun exploded more than 300 years ago

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hot glowing debris from the explosion is

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still visible and a favorite target of

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astronomers who study supernovas

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the researchers scanned cassay using

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chandra's advanced ccd imaging

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spectrometer this revealed

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concentrations of iron sulfur silicon

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magnesium neon and oxygen

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comparing a chemical model of the

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original star to the actual distribution

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of elements seen today they realized

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something amazing

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when the star exploded it turned itself

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inside out most of the iron which

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originally formed deep inside of the

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star is now located near the outer edges

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of the debris cloud

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other heavy elements are also located at

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the outer limits of the debris zone

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these data show that elements cooked

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deep inside stars are not necessarily

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trapped inside

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supernova explosions can free them

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spewing core materials into deep space

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there the atoms of life intermingle with

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other interstellar atoms and molecules

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forming clouds of gas that collapse to

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form new stars new planets and maybe

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just maybe new life forms

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we are star stuff after all