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solomarineris
2009-Feb-20, 06:48 PM
#a) Stars must have been ignited simultaneously (give & take 1 billion yrs)
#b) Galaxies must have been formed simultaneously.
My reasoning is a simple one;
We don't see fireworks up there, i.e. we don't see abundance of supernovae in action, heck, if we see one in a year we jump up & down.
This Universe must be very young. We could witness a different, fiery Universe if we were to succeed to live another 10billion yrs.

Peter B
2009-Feb-20, 06:56 PM
What?

I'm pretty sure most cosmologists and astronomers would agree with your two statements, but the reasoning you've used to get there seems a bit off the mark.

I don't see how you get from "we don't see fireworks" to "this universe must be young". As far as I understand, none of the universe's first generation of stars are still in existence - they were massive and lasted only tens of millions of years before exploding in supernovas and seeding the universe with heavier elements. I understand our Sun is considered to be a third generation star, and I assume this would be the same for most stars in our part of the galaxy.

And, uh, welcome to the BAUT Forum.

pzkpfw
2009-Feb-20, 07:55 PM
The age of the Universe is thought to be about 13-14 billion years.

So a range of 1 billion years doesn't seem all that "simultaneous".

Either way, to me, this concept backs up the idea of a kind of "start point" to our history of the Universe (Big Bang) as opposed to a steady-state Universe (where over time we'd have had a spreading-out of the cycle of star birth/re-birth).

Sam5
2009-Feb-20, 08:10 PM
Let me ask all the experts a question...

Do ALL stars always end up as a Nova or Supernova? Or do some just go dim without a big flash?

Swift
2009-Feb-20, 08:10 PM
#a) Stars must have been ignited simultaneously (give & take 1 billion yrs)

I don't believe that is correct.
According to this (http://en.wikipedia.org/wiki/Milky_Way), "the age of the oldest star in the Galaxy yet discovered, HE 1523-0901, is estimated to be about 13.2 billion years". According to this (http://astrobiology.nasa.gov/ask-an-astrobiologist/question/?id=93), the average age of a star in the Milky Way is 6.3 billion years old, and there are parts of our galaxy where stars are currently forming. I don't think there is any evidence that all the stars in our galaxy, let alone the entire Universe, were formed in a 1 billion year period of time.

aurora
2009-Feb-20, 08:48 PM
Let me ask all the experts a question...

Do ALL stars always end up as a Nova or Supernova? Or do some just go dim without a big flash?


No, it depends on the mass of the star. Stars of the size of our sun go through a red giant phase where they give off shells of gas, and then shrink to white dwarfs, with no nova or supernova unless something else interacts.

I'll also point out that stars continue to be formed, even though our galaxy is relatively quiet, check out the Orion Nebula sometime. An area with new stars being formed.

Dgennero
2009-Feb-20, 09:13 PM
I'll also point out that stars continue to be formed, even though our galaxy is relatively quiet, check out the Orion Nebula sometime. An area with new stars being formed.

Yes, as in young T-Tauri stars:
http://www.daviddarling.info/encyclopedia/T/TTauri.html

cjameshuff
2009-Feb-20, 09:45 PM
No, it depends on the mass of the star. Stars of the size of our sun go through a red giant phase where they give off shells of gas, and then shrink to white dwarfs, with no nova or supernova unless something else interacts.

And the small red dwarfs that litter space outnumber the more visible stars and mostly won't get around to dying until the universe is hundreds or thousands of times older, finally collapsing into small white dwarfs.

slang
2009-Feb-20, 10:40 PM
we don't see abundance of supernovae in action, heck, if we see one in a year we jump up & down.

Really? List of Recent Supernovae (http://www.cfa.harvard.edu/iau/lists/RecentSupernovae.html). I make that, for 2009, almost 1 per day, unless I'm misunderstanding this list. For a more historic perspective: List of Supernovae (http://www.cfa.harvard.edu/iau/lists/Supernovae.html) (warning: huge page).

EDG
2009-Feb-21, 03:36 AM
And the small red dwarfs that litter space outnumber the more visible stars and mostly won't get around to dying until the universe is hundreds or thousands of times older, finally collapsing into small white dwarfs.

They may not even do that - they'll just use up all their hydrogen and become helium dwarfs (I presume there's some kind of collapse involved, but would a helium dwarf be the same as the white dwarfs that we see today? I thought WDs were the carbon cores of stars)

fifelad55
2009-Feb-21, 11:57 AM
No, it depends on the mass of the star. Stars of the size of our sun go through a red giant phase where they give off shells of gas, and then shrink to white dwarfs, with no nova or supernova unless something else interacts.

I'll also point out that stars continue to be formed, even though our galaxy is relatively quiet, check out the Orion Nebula sometime. An area with new stars being formed.

Correct.

Stars that start off with a mass more than a certain times the mass of the Sun will destroy themselves in a supernova explosion before going on to end their lives as either pulsars or black holes.

A nova is, I believe, quite different. Here a white dwarf is pulling matter from a companion star. There is a mass limit to white dwarves of 1.4 times the mass of the Sun and when this is reached, the star ejects a lot of material to become a nova. Please correct me if I'm wrong, but I think the brightness of these events is constant and when found in a distant galaxy, they can be used to determine the distance to that galaxy.

Alan

Pickled Tink
2009-Feb-21, 12:06 PM
They are the same luminosity (Unless something kooky happens to set it off, like a star collision), and the difference in apparent brightness to what we know of their luminosity lets us figure out how distant they are. Unless one of those bizarre events occurs to throw off our readings.

So yeah, you are correct.

fifelad55
2009-Feb-21, 12:09 PM
#a) Stars must have been ignited simultaneously (give & take 1 billion yrs)
#b) Galaxies must have been formed simultaneously.
My reasoning is a simple one;
We don't see fireworks up there, i.e. we don't see abundance of supernovae in action, heck, if we see one in a year we jump up & down.
This Universe must be very young. We could witness a different, fiery Universe if we were to succeed to live another 10billion yrs.

The universe is far from being very young. It is about 13.8 billion years old. This is backed up by both theory and observation of the background radiation from the very early universe. This is now so faint that it can only be viewed in the microwave portion of the electromagnetic spectrum.

Also, take into account the number of white dwarf stars in existance. These stars must have been around for a very long time to use up all the hydrogen in their core and then to convert the helium into carbon and heavier elements.

Alan

Murphy
2009-Feb-21, 05:34 PM
The universe is far from being very young.

Well that kind of depends on what you think of as "young" and "old". If the Universe will keep expanding forever, then in 10 Trillion years time if there is any lifeforms left, them would probably regard out time just ~13.7 Billion years after the Big Bang, as very young indeed.

"Age" in this case, is a matter of perspective.

BigDon
2009-Feb-22, 05:21 AM
Well that kind of depends on what you think of as "young" and "old". If the Universe will keep expanding forever, then in 10 Trillion years time if there is any lifeforms left, them would probably regard out time just ~13.7 Billion years after the Big Bang, as very young indeed.

"Age" in this case, is a matter of perspective.

I'm with Murphy here, though I think I read somewhere things might get "pecular" around the three trillion year mark. Still that's 3,000 billion.

mugaliens
2009-Feb-22, 08:22 PM
I'm with Murphy here, though I think I read somewhere things might get "pecular" around the three trillion year mark. Still that's 3,000 billion.

So far we're less than 1/2 of 1% of the way towards that 3,000 billion mark, so...

m1omg
2009-Feb-22, 09:30 PM
I'm with Murphy here, though I think I read somewhere things might get "pecular" around the three trillion year mark. Still that's 3,000 billion.

Interesting.From where you got the 3 trillion years time?

http://en.wikipedia.org/wiki/The_Five_Ages_of_the_Universe

The era when stars prevail will last up to 100-1000 trillion years :).

WayneFrancis
2009-Feb-23, 12:15 AM
#a) Stars must have been ignited simultaneously (give & take 1 billion yrs)
#b) Galaxies must have been formed simultaneously.
My reasoning is a simple one;
We don't see fireworks up there, i.e. we don't see abundance of supernovae in action, heck, if we see one in a year we jump up & down.
This Universe must be very young. We could witness a different, fiery Universe if we were to succeed to live another 10billion yrs.

To statement A. No stars must not have been ignited at the same time. We seen new star being born and die all the time.

To statement B. Not really. While the galaxies did initially form very early on galaxies are continuing to "form" by merging together.

Let us take our sun for example. It is only ~5 billion years old where our galaxy and many of its starts are much older than that. We also see giant blue stars out there that only live a few million years. Unless you class a 13 billion year range as happening "simultaneously" then you need to use another word.

Just because we don't see supernovas every night when we look up at the sky doesn't mean much. We can only see a few thousand stars with the naked eye and given that we wouldn't expect to see a death of a star all that often. We don't live very close to a star forming region so the fact that we don't see them turn on when we look up isn't a big deal either. Even with telescopes star forming regions tend to be very dusty and probably obscure many new stars that are formed.

Are you trying to claim the universe is only a few thousand years old?

WayneFrancis
2009-Feb-23, 12:51 AM
Correct.

Stars that start off with a mass more than a certain times the mass of the Sun will destroy themselves in a supernova explosion before going on to end their lives as either pulsars or black holes.

A nova is, I believe, quite different. Here a white dwarf is pulling matter from a companion star. There is a mass limit to white dwarves of 1.4 times the mass of the Sun and when this is reached, the star ejects a lot of material to become a nova. Please correct me if I'm wrong, but I think the brightness of these events is constant and when found in a distant galaxy, they can be used to determine the distance to that galaxy.

Alan

Someone can correct me if I'm wrong but both are classed as supernova
The former is when a massive star dies. The resulting supernova is different for each star depending on its mass, size, chemical composition.

The second type, a white dwarf that has matter accreting onto it, will, if enough mass is added, supernova. This is classed as a Type 1A supernova and is the really useful type of supernova. This is because Type 1A supernova are all supposed to be almost exactly the same.

Our sun will neither super nova or even nova, which is a similar process as type 1a Supernova.

solomarineris
2009-Feb-23, 03:01 PM
The universe is far from being very young. It is about 13.8 billion years old. This is backed up by both theory and observation of the background radiation from the very early universe. This is now so faint that it can only be viewed in the microwave portion of the electromagnetic spectrum.

Also, take into account the number of white dwarf stars in existance. These stars must have been around for a very long time to use up all the hydrogen in their core and then to convert the helium into carbon and heavier elements.

Alan
Alan,
When I observe the size of universe 13.8 billion years hardly impress me.
I know it is a known fact (almost) that we know universe is this old. When we observe universe do we see alots of dying galaxies? Do we see any collapsing Galaxy?
I was incredibly impressed when Mr. Fillipenko said "The observable universe wee see today might be as small as a neutron compared to rest of the universe".
My perception is that all the galaxaies we observe today must've been formed within few billion years of each other.

Pamela Gay was saying in her Astronomy cast podcast "someday every Galaxy will exhaust their fuel, it will be a cold universe".

m1omg
2009-Feb-23, 03:24 PM
Alan,
When I observe the size of universe 13.8 billion years hardly impress me.
I know it is a known fact (almost) that we know universe is this old. When we observe universe do we see alots of dying galaxies? Do we see any collapsing Galaxy?
I was incredibly impressed when Mr. Fillipenko said "The observable universe wee see today might be as small as a neutron compared to rest of the universe".
My perception is that all the galaxaies we observe today must've been formed within few billion years of each other.

Pamela Gay was saying in her Astronomy cast podcast "someday every Galaxy will exhaust their fuel, it will be a cold universe".

Science is not based on gut feelings and guesses.
We don't see any "dying" or "collapsing" galaxies.Galaxies have plenty of gas to form new stars for trillions of years.And how a galaxy can "collapse"?

solomarineris
2009-Feb-23, 03:30 PM
[QUOTE=WayneFrancis;
Are you trying to claim the universe is only a few thousand years old?[/QUOTE]

No Wayne,
I'm not saying that at all, I'm not gonna volunteer myself to be a "Village Idiot".
Although it would be fun to see a young earth creationist among us.

solomarineris
2009-Feb-23, 03:32 PM
And how a galaxy can "collapse"?
Are you saying it is impossible?

WayneFrancis
2009-Feb-24, 12:02 AM
Alan,
When I observe the size of universe 13.8 billion years hardly impress me.
I know it is a known fact (almost) that we know universe is this old. When we observe universe do we see alots of dying galaxies?


Define "dying", do you mean running out of fuel for its stars? No one would expect any galaxies to be doing this. Forgetting expansion ripping stuff apart there will be galaxies for many more billions of years. The longest burning stars could burn for 10 trillion years or more....so if its like looking one month old baby and saying "why isn't he dead yet?". A better analogy is if a galaxy dies when the last star in it winks out then its like looking at a a bunch huge healthy family and saying "why aren't they dead? How many sperms and eggs can these people possibly have?"

Since the majority of stars are classed as red dwarfs and these red dwarfs can have life spans of 10By-10Ty and the universe is calculated at only ~14By one that does the math can see that even small galaxies with only ~10M stars the odds that all of them would have burnt out by now is VERY small and this isn't even considering that there is still material out there to make more stars



Do we see any collapsing Galaxy?


Again define "collapsing" Galaxies are held up by pressure from energy released during fusion. There is no reason for a galaxy to collapse in on itself. To do so you would have to remove a HUGE amount of kinetic energy from the galaxy.

We do see a fair bit of galactic merging going on.



I was incredibly impressed when Mr. Fillipenko said "The observable universe wee see today might be as small as a neutron compared to rest of the universe".
My perception is that all the galaxaies we observe today must've been formed within few billion years of each other.


Yup...but a few billion years when compared to 14 doesn't really mean much. A few billion years is hardly considered as "simultaneously" It would be like me looking at my 4 year old god son, his 2 1/2 year old brother and the baby his parents are about to have and say "WOW!!! You've had triplets"



Pamela Gay was saying in her Astronomy cast podcast "someday every Galaxy will exhaust their fuel, it will be a cold universe".

And? Did she say "Someday every galaxy will exhaust their fuel at the same time!"?

Some day OPEC countries will run out of oil. I hardly think that those 12 countries will all run out of oil at the same time or that they started the oil production at the very same time.

WayneFrancis
2009-Feb-24, 12:37 AM
Are you saying it is impossible?

Until you show us some mechanism to remove the angular momentum of all the matter in a galaxy then I will say it is impossible.

At this point in time it is just as impossible as "gravity shutting off" and waking up tomorrow morning floating around.

I didn't read your OP good enough "This Universe must be very young. We could witness a different, fiery Universe if we were to succeed to live another 10billion yrs."

I must have stopped at or got hooked on "very young"

I guess you are right....given that they universe is comparable to a 1 month old baby and there is nothing saying new red dwarfs wouldn't be able to form 10Ty from now, forgetting if expansion spirals out of control and rips everything apart, then yes the universe is VERY young.

WayneFrancis
2009-Feb-24, 12:41 AM
Oh one more thing. When talking about galaxies forming you have to define what you mean by that.

Look at our galaxy. There can be an argument put forward that our galaxy is still "forming". At what point do you consider a galaxy "formed"? Andromeda and the Milkyway will merge in a few billion years. If you lived in the super galaxy that was comprised of the Milkyway, Andromeda and many other dwarf galaxies around these 2 then when would you consider "your galaxy" as being formed?

solomarineris
2009-Feb-24, 03:04 PM
[QUOTE=
And? Did she say "Someday every galaxy will exhaust their fuel at the same time!"?
Some day OPEC countries will run out of oil. I hardly think that those 12 countries will all run out of oil at the same time or that they started the oil production at the very same time.[/QUOTE]

Wayne,
Thanks for educational answers. I used The word "simultaneously" in much broader sense than "same time".

Again, I think within 4,5, billion years after Big Bang Galaxies were formed.
Do you agree that sometime all Galaxies, shining objects will exhaust their fuel supply and universe is going cold?

eburacum45
2009-Feb-24, 03:10 PM
That will happen eventually, but not for many trillion (not billion) years.

solomarineris
2009-Feb-24, 03:32 PM
Oh one more thing. When talking about galaxies forming you have to define what you mean by that.

Look at our galaxy. There can be an argument put forward that our galaxy is still "forming". At what point do you consider a galaxy "formed"? Andromeda and the Milkyway will merge in a few billion years. If you lived in the super galaxy that was comprised of the Milkyway, Andromeda and many other dwarf galaxies around these 2 then when would you consider "your galaxy" as being formed?

No, merging galaxies is not the same as birth of a Galaxy. When we observe a Galaxy with 3-4 billion stars, I am presuming there was a huge energy supply around, so, there was this opportunity to light star after star in few few By time frame.

WayneFrancis
2009-Feb-25, 04:34 AM
Wayne,
Thanks for educational answers. I used The word "simultaneously" in much broader sense than "same time".

Again, I think within 4,5, billion years after Big Bang Galaxies were formed.
Do you agree that sometime all Galaxies, shining objects will exhaust their fuel supply and universe is going cold?

Our sun didn't turn on until about 9 billion years after the big bang. There are stars just turning on now in our galaxy which is 14 billion years.

I don't consider galaxy formation as clear cut as star formation. There is a fairly definite point where a star starts its main thermal nuclear fusion. I'm not so sure at what point a clump of matter can be considered a galaxy.

I will agree that matter was condensing even before the universe became opaque. How long after the universe became opaque the first stars started to ignite and would you consider these stars as being in "galaxies" I'm not so sure. Perhaps it was these first generation stars that collapsed to black holes that created the "seeds" of galaxies.

To me galaxies are evolving (not in a biological sense) and their creation is all dependent on when you are looking at them.

Yes I think at some point in time the universe will essentially exhaust its fuel. Forgetting about expansion eventually the universe will be full of iron and nickle.

How long the "fuel" lasts is another question. Even a supernova provides "fuel" for future stars. With .1 solar mass red dwarfs they'll be quite happy burning as they currently are for another 9.99 trillion years.

WayneFrancis
2009-Feb-25, 04:51 AM
No, merging galaxies is not the same as birth of a Galaxy. When we observe a Galaxy with 3-4 billion stars, I am presuming there was a huge energy supply around, so, there was this opportunity to light star after star in few few By time frame.

There is still a huge energy supply around. The universe still seems to have about 98% of its original fuel still laying around waiting to be used. I've read this post multiple times and still not understanding what you are trying to convey here.

This is how I understand the cosmological evolution.
Early universe is very dense and very hot.
Something causes the universe to expand very rapidly
Quantum fluctuations in the early hot dense universe cause regions of higher densities of matter.
Expansion expands space, and the matter within, apart far enough so the first photons are relatively free to shoot off (universe become opaque)
matter continues to condense.
Now I'm not sure how you would classify the next series of events but huge amounts of hydrogen and helium start to gravitationally collapse into HUGE 1st generation stars that only live a few million years and then supernova spilling much of their mass back out into the universe. The black holes from these 1st generation stars may be the seeds for galaxies. More and more matter start accreting around these "seeds" 2nd generation stars start forming from ejected matter of the 1st generation stars and more hydrogen/helium/lithium from the big bang.
These 2nd generation stars start to turn on and live and dye also seeding more matter for planets and 3rd generation stars (I think planets can form around 2nd generation stars too.)

At what point is a galaxy born? After n amount of stars have "turned on"?

The universe has hardly even tapped the hydrogen it has. I have no doubt that there are pockets of intergalactic gasses out there that are just waiting to run into other clouds of intergalactic gases so that there is enough mass to turn them into stellar nurseries. At which point these would be probably classes as dwarf galaxies. Sure most of this probably happened but I'm fairly confident that there is more of this to happen in the future.