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During a random reading through this site, I found this one: Origin of elements heavier than Iron (Fe)...

The answer was "The formation of many elements in earth was due to Supernova nucleosynthesis" as told by some guy. Here, A question crosses my mind:

  • If the elements were formed due to the explosion of a supernova, then there should be a remnant like a black-hole or a neutron star nearby... Were there any nearby? Or, the famous Big Bang is responsible for this?

(Down-voters - leave comments)

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'nearby' is a long way in astronomical terms. Roughly a Planet will form from a cloud of gas and dust that differentiates by element. Where a planet forms and what it forms from will determine a planets composition. –  Nic Aug 29 '12 at 15:41
the gaseous elemnts are there in the beginning, very little chemistry happens on a planet (unless there's life!). Planets form from the same material as the host star. The central star will blow lighter material away so you end up with more heavy stuff nearer in. –  Nic Aug 29 '12 at 15:50

2 Answers 2

up vote 3 down vote accepted

I'm not sure all the details of the Solar System formation are understood, but the general principles are well established. The dust cloud from which the Solar System formed was probably roughly homogenous. However once the Sun began to form, the dust cloud around it rapidly became differentiated. The heavier non-volatile elements stayed near the Sun while the lighter more volatile elements were blown outwards. That's why the inner planets are rocky while the outer planets are gaseous or icy. Incidentally, the water on Earth probably came from comets after Earth was formed, though views are mixed on this subject.

The dust cloud was probably formed by supernovae of Population II stars, and you're correct that these would have left remnants of some form. However dust clouds are big, and were even bigger when first formed. The nebulae where we see star formation have had time to contract and become more dense since the supernovae that formed them. In addition, it's been (at least) 4.5 billion years since the last nearby supernova. There has been plenty of time for the supernovae remnants to wander around, so it's no surprise we don't have one next door.

Having said that, I've never seen an estimate for the density of Population II supernovae remnants, and I'd be interested to know if there's a firm number for this.

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Yes, the heavy elements were formed in supernova explosions that happened before the birth of the solar system. These elements come from not one but many supernovas that happened at different times during the life of the galaxy.

The sun goes around the centre of the galaxy about once every 200My. Hence, during the sun's life (~5 Gy) we have circled the galaxy about 25 times. So have all the other stars in our neighbourhood, but their orbital period varies with the distance of the star from the centre of the galaxy. See http://en.wikipedia.org/wiki/Milky_Way for more details. As a result, stars that were close to each are gradually drifting apart, and there is no way of telling which supernova(s) our elements come from.

It's also likely that the collapse of the solar nebula was triggered by a supernova. That supernova would have exploded only a short time before the birth of the sun, but again there is no way of finding it.

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