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I have read about and heard about the theory that most of the heavy elements we have here on Earth came from colliding neutron stars rather than by way of supernovae.

I'm not sure how strong this theory is, but I wonder if a LIGO (and backup observational/ gamma ray) detection would help answer this question in any way.

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    $\begingroup$ Could you give references for that theory? $\endgroup$ – Grimaldi Sep 19 '17 at 4:35
  • $\begingroup$ Like Grimaldi said: Please always provide references for theories or discoveries $\endgroup$ – Carl Witthoft Sep 19 '17 at 11:50
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    $\begingroup$ Neutron star collision is now becoming the predominant model for the production of heavy r-process elements. $\endgroup$ – Rob Jeffries Sep 20 '17 at 10:12
  • $\begingroup$ There you go, my reference is the comment above. $\endgroup$ – Jack R. Woods Sep 21 '17 at 2:21
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I just found out the answer to my question from a live press release on You Tube that has been covered by blogs like this: http://news.nationalgeographic.com/2017/10/gravitational-waves-discovered-neutron-stars-pictures-science/

What LIGO does is tell you what is causing the gamma ray burst that can be studied different ways. The highly anticipated announcement I just watched explained that LIGO observed the neutron star merger (they're calling the event a kilonova). With the help of VIRGO, the area of the sky could be narrowed down better than previous LIGO detections. LIGO told us the masses of the bodies, the distance to the objects, how much mass was ejected and thus what the end product of the collision is expected to be.

We have observed many gamma ray bursts and this one was not particularly bright, but LIGO told astronomers to check this one out and so it was being observed within a few hours.

The electromagnetic spectrum of this event was collected and very broad lines were detected which are believed to be caused by heavy elements being ejected at near light speeds.

By our knowledge of how often these "kilonovae" should happen and the volume of elements heavier than iron thought now to have been emitted (16 Earth masses was the number mentioned in the press release), it can be said that a majority of many of the heavy elements we see around us may have come from these events.

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  • $\begingroup$ You shouldn't believe everything in press releases., Especially if you've seen one that says kilonova events produce all the elements beyond iron (which is patently untrue).. Elements beyond iron are produced in a number of ways. Merging neutron stars may be a significant contributor to the r-process component. $\endgroup$ – Rob Jeffries Oct 16 '17 at 18:26
  • $\begingroup$ Sorry, I misrepresented what was said. I think it would be more accurate to say that the evidence supports that kilonovae produce a majority of certain elements heavier than iron (ie. gold). $\endgroup$ – Jack R. Woods Oct 22 '17 at 17:33
  • $\begingroup$ That might be more accurate, though given that the "yield" from this event is only known to a factor of 3 and the Galactic rate of NS mergers is only known to a factor of 3, then the production rate of some elements heavier than iron is only known to an order of magnitude. In any case, the relevant sentence in your answer is still incorrect. $\endgroup$ – Rob Jeffries Oct 22 '17 at 20:27
  • $\begingroup$ @Rob Jeffries I've edited my "answer". Hopefully, this will be better. I also urge anybody reading this to checkout your answer to the question of "why is this important?". $\endgroup$ – Jack R. Woods Oct 23 '17 at 21:09
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Yes it will, in the sense that one of the major sources of uncertainty is how common these events are. The detection of (a population) of such events will give us a handle on that number, at least for the present-day milky way.

Indeed, the one detection of GW170817 has moved us from an upper limit situation to getting the rate (in the local universe) to an order of magnitude.

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  • $\begingroup$ Would Ligo get a good enough picture of what happens to add a lot of info??, and that's assuming it observes a collision at all. I would think collisions like that are quite rare if limited to the Milky way. $\endgroup$ – userLTK Sep 20 '17 at 0:29

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