Philo

I've been doing some research on the life-cycle of a star for a novel I'm writing and I understand the life-cycle stages that a star like ours will go through. I understand how Sol will run out of hydrogen fuel and begin burning helium as it enters the red giant stage.

What I don't know is how long the red giant stage takes. I understand it may be 4 billion years until it starts, but what I'm really interested in is how long it takes.

Say you're standing on earth and you're protected from the effects, the sun begins to dim one day and expand. How long will it take for the earth to become to hostile to live on? I understand that the sun's corona may expand out to the orbit of Venus, utterly consuming Mercury and Venus. Does this happen in years? Centurys? 100 million years?

Now for the details: Will the effects be noticible to the average person year to year? decade to decade? Basically would one notice in a life time?

Any help - discussion or links etc... would be appreciated.

ExoticaRose

Well, I don't know much, even though I'm supposed to.

But...I believe that if it takes, say 4 billion years to consume the hydrogen fuel, The next source of fuel will be consumed much faster. I heard that it would take years to consume hellium fuel for a midsize sun. Then Months for the next.

So basically if the sun takes 4 billion years to run out of hydrogen, then It shouldn't take too long for the sun to become a full fledged red giant. While I don't know the precise time, It should be noticable.

I think.

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Philo

You're supposed too? I'm intrigued.

When you say the next source of fuel, do you mean after the hydrogen, the star will burn helium and then when thats gone it starts in on something else (carbon etc...)? Does it go by atomic weight, consuming heavier and heavier elements? Sounds cool.

The observable part is what I need. Part of my story just won't work if it takes 100,000 years to make a noticible difference, no one would care.

Thanks ExoticaRose.

barnsturm

100,000 years in the life of a star is basically a day. No one is going to notice. Stars don't do anything quickly except right near the end of their existence. Of course, for fiction's sake, you could have something/someone external agitate an unexpected change.

Google "star life span" and you will get quite a few astronomy hits.

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Philo

Thanks Barnsturm, I'll give it a try. My previous searchs (with other search phrases) yielded plenty of results but the info was essentially the same. All the stages are listed but missing helpful timeline/processes information.

There are some things that happen in a stars life that happen quickly. A nova may take a while to build up, but when it goes its quick. Sol is too small for that ,but during the red giant phase, the outer corona may sluff off numerous times, and this will happen sudenly. I just don't know when, or how often in the sequence.

Most resources discuss the big picture: time scales of millions and billions of years. Not much to read about on the smaller time scales so far. Thanks again.

crzywriter

i dont think that it would be noticeable in one person's lifetime. i looked this up on the internet, and it siad 5 to 10 billion years.

either way, its a really long time

mammamaia

as someone above suggested, just google for what you want to know... the relevant discipline is 'astro-physics'...

probably the most specific info you're looking for is that it will take too long for any mere human to notice even in a lifetime... there probably won't be any instantaneous 'big bang' even billions of years from now... it'll more likely be a long, drawn-out whimper...

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Philo

Thanks everyone, I have a feeling I know where this one is headed. I'll keep searching.