# HR diagram problem help

1. Mar 2, 2008

### Tuugii

how to solve it?

thanks,
Tuugii

Last edited: Mar 2, 2008
2. Mar 2, 2008

### Astronuc

Staff Emeritus
How about trying to write an equation for stellar evolution. One has a 1M (solar mass if I read the symbol correctly) leaving the main sequence at 20 L. What's the significance of that?

We ask students to provide some work and effort when asking for assistance.

Last edited: Mar 2, 2008
3. Mar 2, 2008

### Tuugii

thanks a lot. But what is the equation of evolution? if you can provide me a little more info on that, I think I can make it further.

Tuugii

4. Mar 10, 2008

### Astronuc

Staff Emeritus
Here are some useful notes on stellar lifetimes. I haven't gone through the details, but there appears to be some variation. It would be worthwhile to do a comparison.

THE MAIN SEQUENCE
http://www.astronomy.ohio-state.edu/~ryden/ast162_4/notes14.html
http://ftp.astronomy.ohio-state.edu/~pogge/Ast162/Unit2/mainseq.html

http://www.astronomynotes.com/evolutn/s8.htm

Star main sequence lifetime = [star's mass / star's luminosity] × 1010 years.
Star main sequence lifetime = 1010 / (star's mass)(p - 1), where p = 3 for stars more massive than 30 solar masses and p = 4 for stars less massive than 10 solar masses.