How have supernovae shaped the evolution of heavy elements in the Milky Way?

[sumi-e]

Hi, I'm new here. Can someone help me with several sets of questions?

I know the estimated age of the Milky Way. There is information that there are various types of supernovae in the Milky Way that occur on the average of 2.2 to 2.7 per century.

My first set of question: Is this average of supernovae per century constant going back 10 billion years or so? If the average of supernovae in the Milky Way per century changes as you go back in time, what is the change? And why a change? Is there an estimation of the total number of supernovae that has occurred since the formation of the Milky Way? What is that number? How is the number calculated?

Second set of questions, if I may: On the average (or more detailed if the information is there), what amount of heavy elements are produced by a supernova? What is the total estimated amount of heavy elements in the Milky Way? Are the number of supernovae sufficient to account for all the heavy elements in the Milky Way (excluding for the moment any prior collision with another galaxy and the elements that may have come from it)?

Much thanks,

--Greg

 

[SteamKing]

Question 1. Who knows? Human astronomical records at best go back about 3000 years, and the earliest records are somewhat incomplete. It does stand to reason that when the universe was young, there were probably more stars prone to form supernovae than exist currently.

Question 2. http://en.wikipedia.org/wiki/Supernova_nucleosynthesis

 

[Chronos]

Supernova were more common in the past when massive stars were more common. The metallicity of current generation stars, like the sun, is about 2%.