Wayward Star

There is something strangely satisfying when nature thumbs her nose at our scientific theories. This article in space.com describes a star gone super-nova too soon, just hours after a major star eruption.

I’ve never been completely comfortable with the theories of stellar evolution. The theories say that while a star is on it’s main sequence, hydrogen burning, it will increase in diameter by between 40% and 100%.

The sun is said to have increased in both size and temperature to the point where it’ s current luminosity is 25-30% more than it was four billion years ago. This would imply an increase of around 5% in the last 500 million years but there is no evidence of that.

By most accounts while our Sun won’t run out of hydrogen for another five billion years or so, they say it will swell and boil off the oceans in the next 500 million to one billion years. But given that the last 500 million years doesn’t seem to fit the models I don’t have a lot of faith that the next 500 million will. I’d hang around to check it out if I had the option but I don’t think I will.

Enter Alpha Centauri, 1.09 solar masses, 1.5 times the luminosity of the sun. I’m puzzled by this because a stars lifetime is normally estimated as 1/M2.5, in other words Alpha Centauri will only live about .81 as long as our Sun owing to the higher rate of hydrogen consumption. What I find interesting about this is that in spite of the higher mass, in spite of the higher age, Alpha Centauri’s spectral temperature is identical to our own Sun’s.

I tried to find a model that would show what to expect of our own Sun in terms of diameter and temperature throughout the main sequence. What I found, to my dismay, is that there are four or five and none of them seem to agree with observation. I also found estimations of core temperatures and density varied radically from one model to the next. I hope that this surprise stellar explosion may lead to a new and improved model.

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