Stars and Black Holes

[Harry Costas]

Hello All I was asked to start a thread by Ryan.

 

So here it is

 

Form many years I have wanted to know.

 

How is a Star formed?

What types are there?

 

Do Black Holes form from stars?

 

Do Black Holes form stars?

 

Is the process from stars to Black Holes to Stars a recyclic process?

[Jay-qu]

Stars form when large amounts of hydrogen gas compress due to the mutual gravitational attraction of the particles, as it compresses it heats up, eventually if there is enough hydrogen it will be compressed to the point where hydrogen nuclei start to fuse together releasing vast amounts of energy.

 

Check out racoon's thread on What types of stars for your 2nd question.

 

Yes, black holes form from stars - not the other way around, there is no recyclic process.

[adam_rockstar]

that just pretty much summed it all up ;)

[Harry Costas]

Hello all

 

 

Birth of stars

http://www.stsci.edu/stsci/meetings/shst2/ballyj.html

Quote:

"Stars are born in the dense cores of 10^6 to 10^6 M giant molecular clouds (GMCs). The total mass of molecular gas in the Galaxy is about 2 to 4 *10^9 M and there is a comparable amount of atomic hydrogen (HI). Thus, the total reservoir of interstellar gas that is available for star formation is about 5*10^9 M, a few percent of the baryonic mass of the Milky Way. Stars are forming at an average rate of about 3 Myr-1 throughout the Milky Way from this gas.

 

GMCs are supported against global gravitational collapse by magnetic fields and MHD turbulence. Gravitational collapse of molecular cloud cores can occur via two distinct modes (see Shu et al. 1993 and references therein). Magnetic supercritical collapse occurs when a sufficient density of material accumulates in a given region so that the inward pull of gravity overwhelms the outward pressure of magnetic fields. For mean GMC parameters near the Sun, this tends to occur on mass scales of order 10^3 M. Fragmentation must produce ultra-dense sub cores of stellar mass. Collapse can also occur via ambipolar diffusion which occurs more slowly as neutrals slip through the magnetic field (and the ions and electrons coupled to it), lowering the mass where collapse sets in to about 1 M. "

read more

 

other links

http://cfa-www.harvard.edu/swas/science1.html

 

http://www.space.com/scienceastronomy/astronomy/new_matter_020410.html

 

http://www.space.com/scienceastronomy/neutron_stars_031203.html

 

http://www-astronomy.mps.ohio-state.edu/~pogge/Ast162/Unit2/himass.html

quote:

 

"High-Mass Stars

O & B Stars (M > 4 Msun):

 

Burn Hot

Live Fast

Die Young

Main Sequence Phase:

 

Burn H to He in core via CNO cycle

Build up a He core, like low-mass stars

Last for only ~ 10 Myr"

 

the link will take your through the different phases.

[Harry Costas]

Hello Adam

 

Sums what up?

 

Hello Jay

 

That is partly right.

[Eclogite]

Which part do you think isn't right?

 

[Adam meant, I think, that Jay-qu had pretty well summed up the answers to your questions.]

[Racoon]

I am starting to get the concept of this Star stuff...You guys are great!

But I have a question?

 

Stars form from the hydrogen gas and gravitational attraction Jay-Qu mentioned, but where did the hydrogen originate from?

 

I'm not trying to lead into a Creationism spin, but I am wondering where the particles and atoms come from?

Did something come from nothing?

Is this where anti-matter comes into play. Dark matter?

I guess it seems kind of a mystery, at least to me.:)

 

I can buy into Big Bang, but that infinite "ball" of mass? How did it get there?

 

Does anyone know?

Its kinda' like a chicken and egg scenario.

Yes, we know how its made and formed, but where did it come from? :D

 

This Universe is amazingly complex and mysterious; Thats why its so great!

I wish an advanced Alien race would visit and explain to us...;)

[InfiniteNow]

Did

something

come from

nothing?

Congratulations Racoon, you've just asked the $64,000 question. :)

[Eclogite]

Stars form from the hydrogen gas and gravitational attraction Jay-Qu mentioned, but where did the hydrogen originate from?

I wish an advanced Alien race would visit and explain to us...:)

The hydrogen, as you seem to be aware, originated in the Big Bang, according to all the currently popular cosmological theories. Much of the helium and a touch of lithium and berylium emerged at the same time.

 

Never believe anything told you by an advanced alien race. :D Some of them are practical jokers.

[Jay-qu]

Hydrogen is the simplest element, just one proton and one electron - because its so easy to make it is the most abundant in the universe. Of course you can then go on to say where did the protons and electrons come from, but this is where my understanding diminishes. I think they are made up of quarks held together by gluons :beer: cant be certain though.

 

and Harry you asked a question, I gave you an answer and now you tell me Im only partly right :cake: care to tell me whats wrong?:beer:

[Harry Costas]

Hello Jay

 

Your right but don't stop at that level look deeper into star formation.

 

As for Hydrogen

Where did it come from?

 

Hydrogen has been here always. If you think along the lines of the BBT than formed about 14 Billion years ago.

But it can come from the centre of stars as the ultra dense matter releases its subatomic particles hydrogen is formed.

Or it can come from the collapse of matter during the formation of the star core.

It can come from the jets of Black holes.

and so on.

[Eclogite]

But [hydrogen] can come from the centre of stars as the ultra dense matter releases its subatomic particles hydrogen is formed.

Or it can come from the collapse of matter during the formation of the star core.

It can come from the jets of Black holes.

and so on.

Would you care to share the mechanisms for the creation of hydrogen in each of these instances?

 

They are all news to me.

[Harry Costas]

Hello Eglogite

 

Look it mate, do some homework.

I'm off to bed,,,,,,,,,

[Eclogite]

Harry,

I am pretty certain I don't need to do any homework on this one. The vast bulk of the hydrogen in the Universe was created during the early phases of the Big Bang. Subsequently a very small amount is produced by two mechanisms, neither of which is in your list.

 

a) Spallation: nuclear fission (generally of carbon, oxygen or nitrogen) initiated by direct impact on the nucleus by high energy cosmic rays.

:confused: Spontaneous nuclear fission of unstable isotopes.

 

I am unaware of any of the reactions of nucleosynthesis taking place in the core of stars that will release significant numbers of protons. This applies whether in the hydrodynamically stable state of normal stellar processing, or the special conditions applying during a supernovae. That appears to eliminate the first two items on your list.

 

Black holes don't emit anything (I'm ignoring the possible mechanism of evaporation via virtual particles). So, I am confused by what you are referring to here.

 

So, I ask again. You seem to be aware of processes for creating hydrogen that I am unaware of. I would be interested to learn what these are. Please amplify.

[Harry Costas]

Hello Eglogite

 

First lets look at jets from Black Holes and Stars.

 

Read this link on the formation of stars

 

http://www.stsci.edu/stsci/meetings/shst2/ballyj.html

http://antwrp.gsfc.nasa.gov/apod/ap060203.html

http://antwrp.gsfc.nasa.gov/apod/ap030127.html

 

 

Read this on Black holes ejections.

http://antwrp.gsfc.nasa.gov/apod/ap971202.html

http://antwrp.gsfc.nasa.gov/apod/ap010905.html

http://antwrp.gsfc.nasa.gov/apod/ap031128.html

http://antwrp.gsfc.nasa.gov/apod/ap060412.html

http://antwrp.gsfc.nasa.gov/apod/ap970405.html

http://antwrp.gsfc.nasa.gov/apod/ap970613.html

http://www.jb.man.ac.uk/merlin/about/layman/jet.html

http://antwrp.gsfc.nasa.gov/apod/ap041211.html

http://antwrp.gsfc.nasa.gov/apod/ap990216.html

 

about Black Holes

http://cosmology.berkeley.edu/Education/BHfaq.html

 

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What happens to matter when it enters Black Holes, neutron stars and quark stars.

 

Matter degenerates down to an ultra dense plasma matter.

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http://plasmadictionary.llnl.gov/terms.lasso?-MaxRecords=1&-SkipRecords=0&-SortField=Term&-SortOrder=ascending&ABC=Q&page=detail

Term: Quark-gluon plasma

Definition: A state of matter in which quarks and gluons, the fundamental constituents of matter, are no longer confined within the dimensions of the nucleon, but free to move around over a volume in which a high enough temperature and/or density prevails. This type of plasma has recently, 2/2000, been observed indirectly by the European laboratory for particle physics, CERN. These plasmas result in effective quark masses which are much larger than the actual masses. Calculations for the transition temperature to this new state give values between 140 and 180 MeV. This is more than 10,000 times the nominal fusion plasma temperature of 10keV. 150 MeV is the characteristic energy of a particle in a plasma at roughly 1.5 trillion Kelvin. This corresponds to an energy density in the neighborhood of seven times that of nuclear matter. Temperatures and energy densities above these values existed in the early universe during the first few microseconds after the Big Bang.

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When jets from stars and black holes eject this plasma the subatomic particals are no longer controlled by the super massive electromagnetic and gravitational forces that allow the subatomic partical to move freely.

 

So they reform atoms and one such atom is proton to hydrogen. Other atoms are formed.

 

------------------------------------------------------------------------

 

the reverse occurs with heavy atoms entering star and black holes. They break down to protons before they break down to ultra dense plasma matter.

 

 

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http://www.space.com/scienceastronomy/astronomy/new_matter_020410.html

Astronomers announced Wednesday the discovery of evidence for a new state of matter heavier than any previously known, equivalent in density to stuffing all of Earth into an auditorium.

 

The apparent discovery, made with NASA's orbiting Chandra X-Ray Observatory, provides support for a two-decade-old theory suggesting the existence of so-called "strange quark stars." The findings were discussed at a press conference at NASA headquarters in Washington D.C.

 

The research involved two stars expected to be neutron stars, remnants of exploded stars that are composed primarily of neutrons and would be very dense. One of the stars, however, was found to be much smaller than expected.

 

"It is too small to be explained by the theory that governs neutron stars," said Jeremy Drake, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics.

 

Drake and his colleagues examined a star called RXJ-1856. It was found to be about 1.2 million degrees Fahrenheit (700,000 degrees Celsius) and has a diameter of roughly 7 miles (11.3 kilometers). Drake said it's possible they measured a hot spot, but he thinks it's more likely that the observations are correct and the theory of neutron stars needs revision.

 

A paper on the work will appear in the June 20 issue of the Astrophysical Journal.

 

The other object, called 3C-58, became a new star in the sky in the year 1181, when it exploded. According to neutron star theory, some of the material collapsed into a dense core, while the rest was cast off into space.

 

Now, more than eight centuries later, researchers observed the remaining core with certain expectations about how much it should have cooled off. The star' temperature is less than a million degrees Celsius, far below what was expected.

 

"Our observations suggest that the core of this star is made of a new kind of exotic material," said David Helfand, professor of astronomy and astrophysics at Columbia University in New York. "It appears that neutron stars are not made of pure neutrons after all."

 

Instead, each of the stars in the two new studies may contain exotic particles called quarks.

 

Michael Turner, a widely respected cosmologist at the University of Chicago, said both studies appear to show that Nature is able to produce forms of matter that scientists have been unable to create in laboratories.

 

Quarks are thought to be fundamental building blocks of matter. But they have never been observed alone, instead always existing together as the components of other matter. If they were liberated inside a star, they could theoretically be compressed into a smaller sphere, researchers said.

 

The results "suggest the existence of a new state of matter that's made of undifferentiated quarks," Turner said. "If this is indeed the case, then astronomers have provided us with a stunning insight on quarks."

 

Turner said powerful telescopes like Chandra are making it more and more possible to use the universe as a laboratory to study Nature's tiniest phenomena.

 

Norman Glendenning is one of those researchers who has been unable to isolate quarks in a lab. The senior scientist emeritus at the Lawrence Berkeley National Laboratory said that if the observations are correct, then RXJ-1856 appears to be made only of quarks, and as so it would have a sharp edge, not the gradual fuzzy outer surface typical of neutron stars and other stars.

 

"If all that is so, this star is in a class quite by itself and will be an astonishing discovery of fundamental significance," Glendenning said.

 

And there may be deeper implications to the two discoveries.

 

If the work is correct, "it will tells us that there were two paths that the universe might have taken" at inception, Glendenning said. The other universe, had it developed instead, might have been limited in the sorts of matter that were created.

 

"It made all the difference in the world that the universe evolved along one path and not the other, or else we would not be here to contemplate its wonders," Glendenning said.

 

Anne Kinney, director of the Astronomy and Physics Division at NASA's Office of Space Science, cautioned, "I'd like to emphasize that this is evidence for, not proof of, a new form of matter."

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So! there is much to be learnt.

[Harry Costas]

Hello All

 

As for the Big Bang its only a theory and not actual.

So is other theories

 

Read more on recent findings.

[Eclogite]

Harry,

are you able to stay on topic?

 

We are discussing the creation of hydrogen, which you seem to feel is a commonplace

a) When stellar cores collapse

:confused: When ultra-dense stellar matter 'releases' sub-atomic particles

c) In jets from balck holes

 

You then present a series of links and detailed quotes which contain nothing about the creation of hydrogen in any of the settings you describe.

 

I do not know which of the following is the case:

 

a) You do not understand the contents of the links and think they support your position.

B) You hope to blind people in general, and me in particular, with the volume of superficially related material.

c) You cannot stay on topic and are merely jumping from item to item as it catches your imagination.

d) Other.

 

Which is it? I'd really like to know.