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I want to talk about star death!

My last post made me think more what I was really talking about–being more “special” than a meteorite. Sometimes writing things at 1 am do not come out as polished.

Most people are familiar with the idea that stars are massive hydrogen fusion centers; making helium from hydrogen releasing tons of energy. But what you may not know is stars of significant mass actually fuse elements up to Iron.

What we see on the surface of our Sun and all other stars is actually a vast supermassive ocean of heated non-burning hydrogen. 

Our star along with many others actually contain shells of fusion; zones where the heat and pressure have reached levels high enough to begin fusing the elements within to higher atomic masses. As a star ages, a significant amount of heavier elements accumulate in their zones until the heat and pressure again reach a high enough level to begin fusing the next shell. The force and energy from fusing the next shell causes the star to expand. Imagine millions of helium fusion bombs exerting pressure and all of a sudden millions of carbon fusion bombs go off, all more powerful and forceful than the shells above it. 

The force of those fusion reactions pushes out while balancing the force of gravity. In effect, the star swells.

This cycle continues repeatedly down each shell of the star until (unfortunately for the star) it reaches the element Iron. As we found out earlier, the heat of the fusion reactions from the shells above release a lot of energy, in fact more than the energy required to fuse it. But the energy needed to fuse Iron is actually more than the energy released from the reaction. This spells the death of any star within seconds. 

By this time the star has swelled immensely by sometimes billions of kilometers. The reaction of Iron fusion causes a deficit in the energy of the core of a star; as Iron fusion reactions absorb the energy of the surrounding fusion shells, depleting the core of enough energy to sustain fusion. This causes the outward pressure of fusion to drop instantly, causing the core to collapse.

It is within this brief moment, the few seconds of collapse, the last breath of the star’s life, that every element beyond Iron and Nickel are created. The force of collapse is so great, the heat and pressure from this instant alone are significant enough to fuse most of the elements past Iron, and everything else that we have around us today. The core then rebounds, sending a massive shockwave outward. This is what we know as a supernova explosion. 

I said in my first post that at least two stars had to live and die before our Sun came into existence. In reality it could be at least one because one supernova explosion was needed to create all the elements we have now beyond Iron before the creation of our Sun could happen. But in the early universe, hydrogen was the prominent matter source everywhere. More than likely, a supermassive star–which typically live on the order of a few million years to a couple billion years, and keeping in mind the age of the universe at approximately 14 billion years, it makes sense that at least one supermassive star lived and died, providing a portion of the material for planets and life, while another star much like our Sun (which tend to live longer) lived and died before it but after the first. (This also supports the idea of nebulae in star formation. Stars are born by sweeping up enough material, then die spewing matter in all directions to be used in the life of another star.)

Our Sun is a typical main sequence star, meaning it is neither too massive to die as a supernova and neither too small to fall in the red M region and fizzle out as a brown dwarf (at least not immediately). Our Sun most likely will swell as usual, but not attain enough energy and pressure to begin fusing Iron* and explode violently in a supernova explosion. Most models predict it will recede from a maximum diameter of about the distance we are from the Sun**, and live for billions and billions of more years as a white dwarf until eventually most of the heat will have escaped and it will be a lowly brown dwarf at last. 

*Some evidence suggests our Sun will only make it to carbon fusion before it dies.

**Scientists can’t seem to agree completely whether we will be absorbed into the Sun, or if we will just be fried for millions of years before it begins to retreat (which depends whether it will swell past our orbit). 

2 Notes
lucienballard:

Saturn V cutaway drawing.
Saturn V cutaway drawing is by far the most detailed I’ve ever come across.
It’s an original, official Boeing engineering breakdown by Don Sprague and includes everything you ever wanted to know about the Saturn V’s internal workings – right down to millimetre accurate measurements for all major components.
via   Silodrome.com

lucienballard:

Saturn V cutaway drawing.

Saturn V cutaway drawing is by far the most detailed I’ve ever come across.

It’s an original, official Boeing engineering breakdown by Don Sprague and includes everything you ever wanted to know about the Saturn V’s internal workings – right down to millimetre accurate measurements for all major components.

via   Silodrome.com

375 Notes

mcguirkthejerk:

kristinethequeen:

jimmysnowvakk:

This is what pisses me off about Tumblr. You all say you’re so accepting and you don’t want to offend anyone, but then thousands of people reblog something like this because Christians aren’t the minority. You wouldn’t want to offend a Muslim, and if this were offensive to them or another minority, there’d be so many comments about it. But everyone is completely fine with offending a non minority. “You’re not oppressed, you can’t talk!” You know what? I’m a Christian and this offends me and my faith, but nobody’s going to care about that because I’m not oppressed. Tumblr is hypocritical and that needs to stop.

Amen to the comment

Oh my precious lambs:

Examine why you are being offended. Because this is literally how a sunset works. There is not room for debate on this question. There is less room for debate on this than there is on just about any other thing. We are not reblogging because Christians aren’t the minority, dear ones. We are reblogging because after the debate a few days ago, creationists were given the opportunity to pose a question for non-creationists. One of these questions was:

"How can you explain a sunset if their is no god?" (sp.)

Questions, we assume, are posed so that someone might answer them. And yes, there is an answer of how exactly one can explain a sunset given the absence of a divine force. Now, you can certainly posit that God is the creator of all things and so all things came from him including the sun and light refraction and anthrax and kittens and famine and all that jazz.

But you don’t get to deny that THIS IS HOW A SUNSET WORKS, and of the necessary elements of this equation (Sun + Atmosphere + Angle = Sunset), God is not one of them. That’s because everything else is an observable phenomenon, and God is not. You can explain a sunset without God. You can go ahead and believe that God’s part of it all. That’s cool. Lots of people believe stuff like that, and I encourage you to delve into the ways that people make science and their faith jive. But if you are offended by being shown the basic scientific principals behind a sunset, you must be offended by damn near everything. And that seems exhausting. 

In short:

248940 Notes
matthen:

Another interesting property of the logarithmic spiral is revealed if you roll it along a horizontal line. This animation shows the curves traced by points on the spiral, and note that the very centre follows the path of a straight line. The angle between this line and the horizontal is called the pitch of the spiral, and for our spiral galaxy the pitch is around 12 degrees. [more] [code] 

matthen:

Another interesting property of the logarithmic spiral is revealed if you roll it along a horizontal line. This animation shows the curves traced by points on the spiral, and note that the very centre follows the path of a straight line. The angle between this line and the horizontal is called the pitch of the spiral, and for our spiral galaxy the pitch is around 12 degrees. [more] [code

18961 Notes