dwarf galaxy's MassiveStar Vs our milkyway SupeBlackHole

[SuperNard]

I just read a news from here
http://news.yahoo.com/s/space/20091202/ ... estarknown

basically it talk about a discovery of extremely massive star. “Massive enough to create nuclear explosion that eats up the whole star”

from what I read from many more news source, it seem like this type of supper of supper start are more massive then big start that end it life by collapsing in to its core which will turn in to a black hole .

Then I remember that scientist believe that “there is a supermassive black hole at the Galactic Center of the Milky Way.”

at this point, all thing start to make no sense to me.

1.if the supper massive start as see on the news is more massive than the type of star that do the core-collapse and turn to a black hole. Then it should be a lot more massive than the massive black hole at the Galactic Center of the Milky Way, isn’t it?

Because after all, massive black hole we have at the Galactic Center of the Milky Way is still there. seriously i have no idea how big it is, but for sure it is not big enough to totally destroy itself like a supper massive start in SN2007bi did.

That bring me to the next question.

2. as we know, milky way is not a small galaxy. If the answer from question#1 is yes, then how a massive galaxy like the milkyway could be held together by a smaller force than a giant single start that was just totally destroy itself in a dwarf galaxy like SN2007bi?

3. SN2007bi should be even more massive to holdup a supper massive start like that. Isn’t it? Or it simply what we believe about supermassive black hole at the Galactic Center of the Milky Way is wrong? :?:

 

[origin]

I just read a news from here
http://news.yahoo.com/s/space/20091202/ ... estarknown

basically it talk about a discovery of extremely massive star. “Massive enough to create nuclear explosion that eats up the whole star”

from what I read from many more news source, it seem like this type of [super of super stars are more massive than a normal massive star that ends it's life by collapsing to a black whole].

You are right that the story states that a star that has a mass of 200 suns will not collapse to form a black hole.

Then I remember that scientist believe that “there is a supermassive black hole at the Galactic Center of the Milky Way.”

at this point, all thing start to make no sense to me.

These are not related that is the problem!

1.if the supper massive start as see on the news is more massive than the type of star that do the core-collapse and turn to a black whole. Then it should be a lot more massive than the massive black hole at the Galactic Center of the Milky Way, isn’t it?

The massive black hole at the center of the galaxy is not the result of a single large star collapsing. The initial formation of the blackhole may have been a star but most of the mass of the black hole in the center of the galaxy is from inflowing gas, stars and probably other black holes. Once a black hole has formed it will continue to get more massive as more matterial is pulled into it. I do not believe that there is a known upper limit on the mass of a black hole.

Because after all, massive black hole we have at the Galactic Center of the Milky Way is still there. seriously i have no idea how big it is, but for sure it is not big enough to totally destroy itself like a supper massive start in SN2007bi did.

I believe the most recent estimation of the mass is approximately 4 million suns!

That bring me to the next question.

2. as we know, milky way is not a small galaxy. If the answer from question#1 is yes, then how a massive galaxy like the milkyway could be held together by a smaller force than a giant single start that was just totally destroy itself in a dwarf galaxy like SN2007bi?

The galaxy is not held together by the black hole. The galaxy rotates around a common center of gravity. The majority of the observable mass of the galaxy are the stars, which is on the order of 200 billion, which is alot more than the 4 million star mass of the black hole.

3. SN2007bi should be even more massive to holdup a supper massive start like that. Isn’t it? Or it simply what we believe about supermassive black hole at the Galactic Center of the Milky Way is wrong? :?:

[/quote]

Not sure what you mean here. The star in the dwarf galaxy was not at the center of the galaxy. It was not responsible for holding the galaxy together. It was simply a very massive star that was in the galaxy. This star was tiny compared to the mass of the blackhole in the center of the milkyway. The important part of the story is that this star was larger than most astronomers thought was possible and its spectacular death is quite different from other massive stars demise.

 

[Fallingstar1971]

How does a star that big even form? Or perhaps this is the consequence for forming said star.

Oxygen core? So fusing Oxygen could no longer sustain the star? Wow! how big of a star would that have to be? Where the fusion released from oxygen isnt enough and you get the core collapse of an iron core event? Im just having a hard time getting my brain around that. This star must be truly staggering indeed.

Is it the elements? Why did it not form a wolf Rayet Star? What are the conditions required to make this?!?!? Where can we look for more stars like this?

Star

 

[Saiph]

I remember reading about pure hydrogen stars, or pure hydrogen/helium stars (don't remember which) could easily form much larger stars than today's late generation stars.

This is because metallic impurities act, basically, like catalysts in nuclear fusion reactions. It allows fusion at lower temperature/pressures, meaning the stars 'ignite' at smaller sizes. Once they begin fusion, the outporing of energy from the core quickly heats the star, and blows away any other matter that might have accumulated.

With a pure hydrogen (maybe helium? I don't recall) the size required to start the fusion cycle is much, much higher.

That's the first fundamental difference I'd expect in such a hyperstar anyway. But there could be other factors.

 

[SuperNard]

origin, thank you. that clear a lot of my questions.

it amazing how what was left from a dead star can suck in and manage to deal with the mass a lot better than when it was a giant star!

 

[MeteorWayne]

IIRC, the other thing that the non H and He "impurities" do is allow for more efficient cooling. This allows the protostellar cloud to contract much more quickly.

 

[Fallingstar1971]

OK i can understand how metals would allow better cooling........

So the first stars were all pure H and He. They required the bigger sizes to get their fusion going because they were pure. Am I understanding this correctly?

As the cloud cools and contracts, things heat up in the core until fusion ignites?

And the inward pull of gravity is stronger than the outward pressures generated by the heat, which eventually balances when the star ignites?

Am I understanding correctly?

Then this particular star fused up to O, but there was so much mass and gravity that O fusion wasnt enough? This is what blows my mind. I wonder what the math would look like to calculate the upper limit for O fusion. Just to get an idea of the size of this thing.

I was thinking maybe a smaller star in the middle of a dense H cloud, but if that were the case it would have been revealed in the spectra. Is this correct?

Star

 

[MeteorWayne]

You're right on up to the O burning part. At that time, it gets pretty complicated, since depending on the stellar mass there is C, O, Mg, Ne, Si, etc.

This wiki page is a good intro, if you follow all the links contained within for each process you'll get a good understanding. It's much too complicated to explain in a few pages here in the forum

It's a very good read and explains pretty much how all the elements are formed in the various linked sections.
It's really amazing stuff (as are we) :lol:

Wayne.

 

[Fallingstar1971]

Ok so depending on the mass, we could have a supernova at any of those elements.

I will check out that page. TYVM

Star

 

[MeteorWayne]

OOoooppppsss, I forgot the link: :shock:

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

Thanx for the reminder Boris

 

[neilsox]

Part of the problem is we use adjectives instead of numbers such as 400 million solar mass. The extremely massive star is likely less than a millionth that big. When it goes super nova today or a million years from now, it will lose about half of it's mass and be a puny black hole compared to the black hole at the center of our galaxy which is puny compared to some super massive black holes that are more than a billion solar mass. Stars more than about 4 times the mass of our sun go super nova when they are about a billion years old, because their core ran out of nuclear fuel. Possibly the most massive stars eject 90% of their mass (when they go super nova, but I doubt all the mass as the article seemed to imply.
"Then it should be a lot more massive than the massive black hole at the Galactic Center of the Milky Way, isn’t it?" unquote No, in this case extremely massive is more than a million times smaller than super massive. Neither size black hole will blow up. Except for microscopic black holes (none have been found) black holes lose about a millionth of their mass in a billion years. Typically more mass falls in than the black hole evaporates. I don't think we know how the black holes at the center of large galaxies (such as our galaxy) got that big, as our galaxy's supermassive black hole captures perhaps one earth mass per year, so growth is extremely slow.
SN2007bi did. No, not yet, the article is guessing.

"2. then how a massive galaxy like the milkyway could be held together by a smaller force than a giant single star that was just totally destroy itself in a dwarf galaxy like SN2007bi?" Galaxies can be held together without a 100 plus mass star or black hole

The article about "3. SN2007bi" may be correct, but the inference is wrong. Stars do not need a galaxy and galaxies don't need a large mass at the center.
What we believe about the "supermassive black hole at the Galactic Center of the Milky Way is likely" correct. Neil

 

[Fallingstar1971]

OK so now a math problem is setting up.........

We have X amount of energy released from Oxygen fusion.

The total mass of the star will determine its gravity

When the gravity is stronger than the energy output from fusion, the core collapses and fusion kicks in for the next element.

But Oxygen can make all of these things:

O16 + O16 → S32 + γ
O16 + O16 → P31 + p
O16 + O16 → S31 + n
O16 + O16 → Si28 + He4
O16 + O16 → Mg24 + 2 He4

Does each element release a different amount of energy? I would think so since Iron takes more energy to fuse then is released, I would imagine the energy gets less and less the farther up the food chain you go.

Could the spectra of the supernova indicate how much of each element was present? Or does it just say the element is there? How would you determine how much of a star is Carbon, and say, how much is Helium?

Star

 

[MeteorWayne]

I guess you didn't bother to read through the details on the link I provided.
I guess I shouldn't bother then

Yes, each reaction produces (or consumes) a different amount of energy, as you would have found out....

 

[Fallingstar1971]

I wasnt trying to be difficult whats obvious to you isnt as obvious to me. I did read through most of it, but I had to run uptown and wanted to post my question before I left.

And yes, I suppose it could be viewed as a waste of time. When your computer goes down, you call tech support. If your on campus, you will call the NOC. Gee, the person that then answers YOUR questions will then be me or someone JUST like me

So remember, we are all smart in our particular fields. Yours may be physics and astronomy, but mine keeps you talking to your colleges. And all of us in tech support just LOVE those calls from know-it-all professors that just cant understand why their mothers would send them email viruses

Star

 

[MeteorWayne]

The problem is that the questions you are asking have very complicated answers. So my question becomes, why should I spend my time researching the answers for you, if you are not going to follow on with your own effort. I gave you the tools to answer the questions, you didn't read them and came back with another question. If you want to learn, you have to put in some effort, not just ask simple questions with complicated amswers. It's not obvious to me, I have to do the research, just as you need to do, to build up some background in physics.

It's not my specialty, that's meteors. So to answer your questions, I spend an hour or so reading and researching, gave you the links so you could understand it, and you didn't.

Believe it or not, computers are much simpler than physics

 

[Fallingstar1971]

Thats just it though, YOU do not have to. If someone knew the answer offhand, than that is one thing.

ANd no, computers are not as difficult as Physics, not by a long shot. But I will bet money that isnt going to stop you from calling tech support when your machine goes down now is it?

And no, Neither is auto mechanics, but that is not going to stop you from taking your car in for a tune up now is it?

Why Wayne? When you can just apply a little "common" sense and do a little "research" and fix the problems yourself?

I know my questions have complicated answers which is why I ask them. The best answers lead to more questions. Please do not feel obligated to answer them. You did provide a reference point, and for that I thank you. However, its the equivalent of me handing you your computers owners manual and telling you to fix it yourself.

If you understood your computer, then you wouldn't need to call tech support

If you understood your car, then you wouldn't need a mechanic

And if I understood all the wonders of physics, I wouldn't have to post questions here

God I wish I was your Sysadmin. I would teach you just how complicated computers and network administration REALLY is. Then the playing field would be level. And when that last lockup causes the last hair from your head to fall out, I will hand you all my materials on system administration and tell you the answer is in there.......somewhere...... and laugh maniacally as walk away. Oh I'm sure I will hear all about your "deadlines" and how your programs funding will be cut if so-and-so doesn't get his report on time, but hey, you have the answers in that library of books I gave you ...chop chop Like I said, we LOVE those calls from the nutty professors.