humor me, science nerds. i have a question about stars.

[oriecat]

Awesome explanation, Hertz! As Carl Sagan liked to say "we are made of star stuff".

Carli, if you've never seen if, consider renting Sagan's Cosmos dvds. They are really good.

 

[carlita]

thanks, hertz. i pretty much knew everything you said already minus the part about people being made of star bits and whatnot. :razz:

it just seems like such a thing couldn't possibly be as accurate as those studying it would like to think. or as they'd like the rest of us to think. you know what i mean?

 

[Hertz van Rental]

it just seems like such a thing couldn't possibly be as accurate as those studying it would like to think. or as they'd like the rest of us to think. you know what i mean?

Scientists are well aware of the fallability of their theories.
They propose a model and use it to make predictions. If observation matches prediction then chalk a success up. If the prediction is off they try to work out why. If it is right out or nothing like then it is back to the blackboard. But they never stop doing this testing because they believe that sooner or later a 'special case' will crop up that will give them more info and then adjust the theory to give a truer picture.
This is why they constantly test Einstein's Theories. So far he is batting 100%! And this year is 100 years since the publication of his Theories.
Scientists always preface things with 'our current thinking leads us to believe' or words like that. It is generally the press who try to make Science omniscient.
But don't go confusing people like doctors of medicine with scientists - they are more your engineer
The current discovery that has given Astronomers (and a lot of other Scientists) insomnia is the discovery made by a system of satelites working like a big telescope. It was designed to image and map space. It's results have shown quite clearly that our universe is expanding far faster than had been thought.
Now there is this stuff Astronomers call 'dark matter'. You can't see it or do anything with it - the only way they know it exists is because it exerts a gravitational force. The rate of Universe expansion has resulted in recalculations that indicate that physical matter (the sun, moon, stars, you, me..) only makes up 0.03% of the universe. The rest is dark matter!
Dark matter, it is believed, exists in another dimension (there are others, you know) so it actually co-exists alongside 'our' matter. To use popular press language - you could have a dark-matter sofa in your living room and you wouldn't know it, unless you could measure the minute gravity changes it would cause.
This has made them rethink about black holes too.
They exist and 'suck in' matter. Most of this matter will be dark matter, which will considerably increase the mass going in. Where does all this matter go? They think it comes out somewhere else using a 'white hole'. It will come out violently and instantly when the mass builds up enough. Exactly like a Big Bang.
The worst of it is that they believe dark matter to be the 'real' universe - it satnds to reason, really. There's far more of it.
Where does that leave our Universe - the current thinking is that matter as we know it is just an accidental by product: a bit like eddy currents in a stream.
Think about this for a bit and you will see one of the reasons Astronomers have got insomnia.

 

[Corry]

My brain hurts now...but that's ok. I think I've learned more from you in this past week, than I did my entire senior year in high school.

 

[DarkEyes]

okay so stars live for a really freakin long time. and it's not like with dinosaurs and stuff where we've got fossils we can play with so that we can map out a timeline and whatnot.

so how exactly do we know what the real life of a star is like since we can't observe it? i mean, it takes WAAAAAAAAAY too long for anyone to have ever witnessed a change. so sure, we've got lots of stars we can see in all different stages of their lives, but how the hell are we supposed to know which stage comes first and which comes last let alone what order they go in in between that?

i tried to ask my dad about this (an engineer at NASA) and either he didn't understand my question or he just really didn't know. i'd like to thing it was the former because if it's the latter he should be ashamed of himself. :razz:

I Can answer this!!!
A star's age is determined by a number of observable factors: It's temperature, luminosity and composition.

Because thier are so many stars visable to us, we can observe stars of similar properties at different phases of stellar evolution.
As a star ages, it fuses less hydrogen into helium, cools, and expands. also, the number of "metals" or heavy elements (Oxygen, carbon etc.) in it's spectra increases.

I will post again within the week with some info from the web.

 

[DarkEyes]

It's to do with atomic theory.
You can calculate the mass of a star.
You can use spectral analysis to determine it's composition.
Stars generate energy by hydrogen-hydrogen fusion. You can determine the rate of reaction and, knowing how much hydrogen they contain, calculate first phase length. Second phase is when they run out of hydrogen and start a helium-helium reaction. When they run out of helium they colapse and go out. You can work out an approximate life expectancy.
As for obseving the various stages. There are a lot of stars in the sky. There are bound to be stars at different stages of their life.
If you can find the pleiades in the night sky (the seven sisters) - it is actually a large cloud of dust and gas inside which stars are being born. The crab nebula is the remains of a supernova explosion.
Of course this explanation is very much simplified. Stars are quite complex and the size of the star determines it's life cycle.
The thought that always scrolls my nerd:
Atoms are indestructable. ALL atoms have been forged inside of stars (H+H=He, He+He=C and so on) so all the atoms that make up you have passed through countless stars - or to put it another way: countless stars have lived and died so that you can exist.
Think about that.

The highlighted text is incorrect. The pleiades is not a cluster of stars bieng formed in a nebula of 'dust' and gas molecules. It is just a star cluster. There is however 2 nebula's close to it that are in the middle of a three way collision (With the pleiades).

Also, size is not the correct term, Mass is. The more mass the star has at the time of its formation, the faster it will fuse hydrogen into helium, and the sooner it will die. The Most massive stars live for "only" a few million years, wereas the least massive according to current theories of stellar evolution can live longer than 15 BILLION years (Longer than the universe has thus far existed for!).

Also, one last thing, atom's are destructable. Ever heard of splitting the atom? or Atom Smashers (Atomic partice accellerators that smash atoms together at incredibly high speeds, Often destroying both atoms in the proccess.)

At least you got a few things right...
This is not meant as critisism to you hertz, it is just to ensure correct information is given.


THATS MR NERD TO YOU!

Find out more about stars Here

 

[SSP]

Thank you Darkeyes and Hertz van Rental....you saved me a load of typing!

If you have not read it I can recomend "The Elegant Universe" by Brian Greene (IIRC...don't have the book to hand!)

Alex

 

[carlita]

i :heart: hertz. i love stuff like that (dark matter and whatnot) that turns my brain into pudding. and i mean that in all seriousness. i once had a reeeeeeeeeeally long conversation with someone about people who are blind and whether they can ever comprehend what color is let alone how to differentiate between them in their mind. (that's a very crude summary, but you get the idea.) then that took us into whether it's possible for anyone, blind or not, to comprehend every possible color there could be, which THEN turned into whether our capacity for learning is boundless or not. and so on and so on and so on.

chances are, neither of us really knew what the hell we were talking about, but it sure was fun.

anyway, what i think i've gathered from all of this is that i don't have any issue with the process by which astronomers have come to the conclusions that they have... i understand all that. the basic ideas anyhow.

i suppose what gets me is still just what i see as the very good likelihood that it could all be completely wrong. given that the universe is infinite and when it comes down to it, what we think we know isn't even a drop in the bucket as far as what's really out there and everything.

does that make any sense to y'all or am i babbling incoherently? :crazy:

that feeling isn't limited to stars though. i mean, as much as it could be true about stars, it's true about everything else we think we know. i mean, we COULD be right, but given the infinite number of possibilities... how good can the chances really be?

 

[Canon Fan]

i once had a reeeeeeeeeeally long conversation with someone about people who are blind and whether they can ever comprehend what color is let alone how to differentiate between them in their mind.

Thats funny I once had a conversation with someone about the possibility that not one person see's color exactly the same (which actually is true I guess) but I mean REALLY different. Like what red looks like to me may actually be blue to you but because you were taught that it is red that is what your mind interprets as red. Therefore color combinations that would be putrid to most somehow would be just fine to you because of the way your brain "sees" the color's differently.

I was so intrigued that I spent three days learning about how the human eye works by reading everything I could find. Turns out I basically described certain forms of color blindness and eye disease It was fun feeling thoughtful for the moment though!

Sorry to Hi-Jack your thread :blushing:

Hey Hertz have you ever been a guest on the radio program Coast to Coast AM? Formerly with Art Bell? They always seem to have these super-brains on there like you!

 

[carlita]

Thats funny I once had a conversation with someone about the possibility that not one person see's color exactly the same (which actually is true I guess) but I mean REALLY different. Like what red looks like to me may actually be blue to you but because you were taught that it is red that is what your mind interprets as red. Therefore color combinations that would be putrid to most somehow would be just fine to you because of the way your brain "sees" the color's differently.

I was so intrigued that I spent three days learning about how the human eye works by reading everything I could find. Turns out I basically described certain forms of color blindness and eye disease It was fun feeling thoughtful for the moment though!

Sorry to Hi-Jack your thread :blushing:

oh, i assure you i've had the same conversation before. always fun.

and no need to apologize. i'm not picky about my threads strictly staying on topic. they're more interesting when they take turns. :bounce:

 

[Hertz van Rental]

I wrote the explanation off the top of my head in about 2 minutes with what I could remember at the time and without the aid of Google. I last did serious astronomy about 30 years ago, when it was thought that the Pleiades was where stars were being born.
I have, however, just found this more recent information:
'The Pleiades star cluster, also known as the Seven Sisters and Messier 45, is a conspicuous object in the night sky with a prominent place in ancient mythology. The cluster contains hundreds of stars, of which only a handful are commonly visible to the unaided eye. The stars in the Pleiades are thought to have formed together around 100 million years ago, making them 1/50th the age of our sun, and they lie some 130 parsecs (425 light years) away.'
And also:
'Several Pleiads appear surrounded by intricate blue filaments of light. This nebulosity is the result of starlight scattering (reflecting) off minute grains of interstellar dust in the vicinity. The dust particles are inside a cloud of mostly hydrogen gas that the cluster seems to be plowing into.'
So some of the stars are very young and they are in a dust cloud. Hmm. I can't see that I was that far out with my description.
As to ensuring 'correct information is given'. Might I suggest you do a Google search on nuclear particle accelerators to find out how they work and what they do? I think you will find that your description is wildly inaccurate. Unless you would like me to give you a quick and simple explanation?

 

[Scott WRG Editor]

Nope Im implying that nothing is real...you and the rest of the known galaxy are simply figments of my imagination...you just said nerd and my ears perked up.

Damn man, the best your imagination could do included me??? You need to get out more.