Astronomy - help!

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The earliest fossil records indicate that life appeared on Earth about a billion years after the formation of the solar system. What is the most mass that a star could have in order that its life-time on the main-sequence is long enough to permit life to form on one or more of its planets? Assume that the evolutionary processes would be similar to those that occurred on the Earth.

• Astronomy - help! - ,

http://csep10.phys.utk.edu/astr162/lect/mainseq/mainseq.html

Look at the time graph, on the vertical scale find 10^3 million years, then go downward to the horizontal scale and read the answer.

• Astronomy -more help! - ,

I checked out the graph, but when I go to 10^3 vertically, how far over am I looking. There are several lines, which one will tell me how much mass a star could have while on the main sequence to support life? thanks!

• Astronomy - help! - ,

The earliest fossil records indicate that life appeared on the Earth about a
billion years after the formation of the solar system. What is the most mass that a star could
have in order that its lifetime on the main sequence is long enough to permit life to form on one
or more of its planets? Assume that the evolutionary processes would be similar to those that
occurred on the Earth (this assumption may, in fact, not be true, but go with it). What would
you expect the spectral class of such a star to be?