B Number of stars in the universe over time

[BL4CKB0X97]

Hello.Long time,No See.

I am just wondering if anyone can point be in the correct direction. Preferably with a link or a book that I should read as i would like to understand, not just know the answer.

I am just wondering how much the number of stars in the universe has changed over time. Also, has the type and mass of the stars changed as the universe got cooler? I understand the basic stages of our universe, but I presume their is a significant amount of maths to it as well. For instance, is there a Formula for number of star over time (I'm going to hazard a guess that is an expontial curve)?

Thanks!

Also, if someone is willing to let me bounce stupid questions off them as PM's(considerably less embarrassing that public ones) that be great! Let me know.

Oh, and I have been accepted to start an Physics degree in september! Hooray!

 

[phyzguy]

Congratulations on being accepted!

It is a complex question. The first stars are believed to have formed a few hundred million years after the big bang. Studies like this paper have attempted to measure the Star Formation Rate(SFR) as a function of time, and have concluded that star formation peaked around 10 billion years ago (about 3.7 billion years after the big bang) and has been steadily declining since, as shown in the figure below, which is copied from that paper. When stars are formed, more low mass stars tend to be formed than high mass stars. Also, how long stars live is a strong function of how massive they are. Massive stars 10-100 times larger than the sun only live for millions of years, while stars less massive than the sun can live for as long as a trillion years. So as time goes by, there are more and more low mass stars and "stellar remnants" - objects like white dwarfs, neutron stars, and back holes which are what is left over after a massive star lives and dies. Here are a couple of good Wikipedia links to get you going:

https://en.wikipedia.org/wiki/Initial_mass_function
https://en.wikipedia.org/wiki/Stellar_evolution

Feel free to PM me with questions.

 

[BL4CKB0X97]

Perfect! Thank you.
Edit: The link does not work but I found it with a google search anyway.