What is the main sequence and why do stars spend most of their lives there?

[Mk]

What is a main sequence and some interesting things about it? It seems to be a big star and a little star feeding off of each other?

 

[Chronos]

A main sequence is the evolutionary path taken by stars. They start as a big collapsing cloud of gas and end as a burnt out ember. What happens in between is fairly interesting.

 

[selfAdjoint]

And the main sequence was developed as a correlation between spectral class of stars and their surface temperature, which can also be determined from the spectrum; roughly the pattern of lines in the spectrum correlates to the frequency of greatest intensity. Then they saw that their squence tracked the hisotry of the stars.

 

[meteor]

I want to expand a little...

The main sequence is a track in a diagram called Hertzsprung-Russell diagram (HR diagram), and is called "main" beacuse stars pass the major part of their lifes in this track. Stars come to the main sequence from another track called (guess what?) pre-main sequence. Stars that have just arrived from the pre-main sequence to the main sequence are called Zero Age Main sequence stars, and are stars that begin to fuse hydrogen in its nucleus.
Stars let the main sequence through various "exit doors". Some take the Giant branch, others more massive take the Supergiant branch, while others (red dwarfs) end up in the White Dwarf region

 

[chroot]

The "main sequence" is the "adult" phase of a star's life, during which it is steadily fusing hydrogen into helium. The star doesn't outwardly change much at all during the main sequence, which is most of the star's total lifetime.

The main sequence lasts a few hundred million years for very massive stars, but can last as long as tens of billions of years for less massive stars. Our own Sun has a total main sequence lifetime of about ten billion years, of which about half has passed.

- Warren

 

[DB]

Check out the Hertzsprung-Russell Diagram http://home.cwru.edu/~sjr16/stars_hrdiagram.html