Giant stars reveal inner secrets for the first time

Mar 31, 2011
This discovery has led to new insight into how stars evolve.

(PhysOrg.com) -- University of Sydney astrophysicists are behind a major breakthrough in the study of stars known as red giants, finding a way to peer deep into their cores to discover which ones are in early infancy, which are fresh-faced teenagers, and which are facing their dying days.

The discovery, published in the latest edition of the journal Nature and made possible by observations using NASA's powerful Kepler , is shedding new light on the evolution of stars, including our own sun.

The paper's lead author, the University of Sydney's Professor Tim Bedding, explains that "red giants are evolved stars that have exhausted the supply of hydrogen in their cores that powers , and instead burn hydrogen in a surrounding shell. Towards the end of their lives, red giants begin burning the helium in their cores."

The Kepler space telescope has allowed Professor Bedding and colleagues to continuously study star light from hundreds of red giants at an unprecedented level of precision for nearly a year, giving a window into the stars' cores.

"The changes in brightness at a star's surface is a result of turbulent motions inside that cause continuous star-quakes, creating that travel down through the interior and back to the surface," Professor Bedding said.

"Under the right conditions, these waves interact with other waves trapped inside the star's helium core. It is these 'mixed' oscillation modes that are the key to understanding a star's particular life stage. By carefully measuring very subtle features of the oscillations in a star's brightness we can see that some stars have run out of hydrogen in the centre and are now burning helium, and therefore at a later stage of life."

Astronomer Travis Metcalfe of the US National Center for Atmospheric Research, in a companion piece in the same Nature issue which highlights the discovery's significance, compares red giants to Hollywood stars, whose age is not always obvious from the surface. "During certain phases in a star's life, its size and brightness are remarkably constant, even while profound transformations are taking place deep inside."

Professor Bedding and his colleagues work in an emerging field called asteroseismology. "In the same way that geologists use earthquakes to explore Earth's interior, we use star quakes to explore the internal structure of stars," he explained.

Professor Bedding said: "We are very excited about the results. We had some idea from theoretical models that these subtle oscillation patterns would be there, but this confirms our models. It allows us to tell apart, and we will be able to compare the fraction of stars that are at the different stages of evolution in a way that we couldn't before."

Daniel Huber, a PhD student working with Professor Bedding, added: "This shows how wonderful the Kepler satellite really is. The main aim of the telescope was to find Earth-sized planets that could be habitable, but it has also provided us with a great opportunity to improve our understanding of stars."

Explore further: Astronomer confirms a new "Super-Earth" planet

Provided by University of Sydney

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omatumr
1.9 / 5 (9) Mar 31, 2011
Thanks for the interesting report.

I look forward to learning if the cores of red giant stars are the same as the core of the Sun.

Neutron Repulsion [APEIRON (2011) in press]
http://arxiv.org/...2.1499v1

With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo

Shootist
5 / 5 (5) Mar 31, 2011
Dr. Maunel,

The article isn't real clear, but are not "Red Giants", evolved from main sequence stars with masses in the range of ~0.5 solar masses to somewhere between 4 and 6 solar masses?

Can we not point at many "Red Giants" and say, "That is the Sun, 5 billion years from present"?
omatumr
1.8 / 5 (10) Mar 31, 2011
Dr. Maunel,

Can we not point at many "Red Giants" and say, "That is the Sun, 5 billion years from present"?


That is the popular view. But I never took a class in astronomy.

My research has been concerned mostly with nuclear and isotope studies of material in the solar system. Almost 50 years of measurements were required to finally convince us that the photosphere is simply a glowing sphere of waste products (91% H and 9% He) from the Sun's compact, energetic core - a neutron star.

H-fusion generates 35% of the Sun's energy today, but that fraction might change later and cause the Sun to become a "Red Giant."

I do not know. Perhaps studies like this will answer the question.
Nik_2213
5 / 5 (4) Mar 31, 2011
"were required to finally convince us ..."

'Us' ??

I'm sorry, Dr Manuel but, IIRC, the neutron core hypothesis does not yet represent mainstream solar physics and may yet be disproven by helioseismology.
omatumr
2.7 / 5 (6) Mar 31, 2011
Us = Students, Coauthors, and Colleagues.

Thanks for your comment.

I did not mean to imply that the neutron core hypothesis is mainstream.

omatumr
2.3 / 5 (7) Mar 31, 2011
'Us' ??


Coauthors include, for example

1. A professor of mathematics and statistics,
2. A bright high-school student from Germany,
3. Other professors with better credentials than me,
4. A freshman student who graduated in mathematics,
5. Other freshman students who now have PhD degrees.
Shootist
5 / 5 (4) Mar 31, 2011
Dr. Maunel,

Can we not point at many "Red Giants" and say, "That is the Sun, 5 billion years from present"?


That is the popular view. But I never took a class in astronomy.

My research has been concerned mostly with nuclear and isotope studies of material in the solar system.


Yes, I know. I read your posts and try to digest what I understand.

But a hypothesis must be testable. The currently accepted view of main sequence stellar evolution matches well, the currently accepted view of main sequence stellar nuclear processes and the inescapable buildup of "ash" (helium) and the depletion of hydrogen as a fuel source. You say you do not know if main sequence stars evolve into Red Giants, yet the physics itself suggests that is the case.

How can your hypothesis be tested? Can your hypothesis explain the various observed populations of stars as a predictable outcome of neutron repulsion powering stellar bodies?

Decimatus
2.6 / 5 (5) Mar 31, 2011
Oliver, I can't say I completely agree with your neutron repulsion theories(though I am also not saying they are wrong), but I do belive that the truth lies somewhere between your theory and the mainstream when it comes to the actual makeup of stars.

For instance, take a look at that picture attached to the article. Note how there is pretty much no room for heavy elements whatsoever. Given that the expected age of the universe is such that most stars form from some kind of supernova waste, you would have to expect a siginficant core of heavy elements.

Take the planets for example. They formed from the same waste as the Sun, yet most mainstream theories put the sun at some illogical % of H/HE.

Logically, the Sun has to have some large core of heavy elements, making up a high fraction of it's total mass. It could even be a neutron core, though that wouldn't have to be the case.
Decimatus
2 / 5 (5) Mar 31, 2011
Another problem I have with mainstream theories, and this goes along with my prior post, is that the theories usually state that elements beyond FE can not be created through normal stellar fusion, thus requiring supernova to produce.

That just doesn't fit well with me logically.

The Sun is so enourmously massive, that the combination of dense core and all the H/HE/etc sitting on top, should produce enough pressure to have varying degrees of fusion throughout the star, especially at the various element boundaries.

I could even see a transition from heavy element core, to a neutron core being the trigger for most supernova events.

Or not. Either way though, the mainstream theories are far too simplistic and illogical for me to put any stock into.
omatumr
1.7 / 5 (6) Mar 31, 2011
How can your hypothesis be tested?


Our hypothesis was developed to address experimental data:

a.) Missing solar neutrinos

b.) Age dating with short-lived radioactivities

www.omatumr.com/D...Data.htm

www.omatumr.com/D...Data.htm

www.omatumr.com/D...Data.htm

c.) Solar mass-fractionation

www.omatumr.com/D...ata1.htm

www.omatumr.com/D...Data.htm

d.) Nucleogenetic anomalies of elements and isotopes in meteorites and planets

www.omatumr.com/D...Data.htm

www.omatumr.com/D...Data.htm

www.omatumr.com/D...Data.htm

www.omatumr.com/D...Data.htm

www.omatumr.com/D...Data.htm

www.omatumr.com/D...Data.htm

Turn the story around and say the observations are tests.

Does anyone here have a better explanation for the above data?

omatumr
1 / 5 (5) Mar 31, 2011
a.) Nuclear rest mass data and neutron capture cross sections:

www.omatumr.com/D...Data.htm

www.omatumr.com/D...Data.htm

Discussed in these research papers:

1. "Attraction and repulsion of nucleons: Sources of stellar energy"
Journal of Fusion Energy 19, 93-98 (2001)

www.omatumr.com/a...tnuc.pdf

2. "Nuclear systematics: III. The source of solar luminosity",
Journal of Radioanalytical & Nuclear Chemistry 252, 3-7 (2002)

www.omatumr.com/a...sym3.pdf

3. "Neutron repulsion confirmed as energy source",
Journal of Fusion Energy 20, 197-201 (2003)

www.omatumr.com/a...nrep.pdf

"The Sun is a plasma diffuser that sorts atoms by mass",
Physics of Atomic Nuclei 69, 1847-1856 (2006)

http://arxiv.org/.../0609509

"Solar abundance of elements from neutron-capture
cross sections," LPSC, 1033 (2005)

http://arxiv.org/...412502v1

I regret that I will not be available to reply to any comments for a few days.
PinkElephant
4.4 / 5 (8) Apr 01, 2011
All well and good, except a neutron star cannot in principle have a mass smaller than 1.08 solar masses, even before any matter might have accreted on top of it:

http://arxiv.org/...91v1.pdf

What's the TOTAL mass of the Sun? Oh yeah, 1.00 solar masses, by definition.

But who cares about theory? It's not like we actually have ridiculous quantities of observations of stars in the process of forming amid giant molecular clouds, without any help from any neutron star cores... Oh wait, we do!
That is the popular view. But I never took a class in astronomy.
Oh, hell. That WOULD explain a lot. After all, why should one familiarize oneself with even the very basics of a field to which one aspires to contribute?

Naaah, existing knowledge and data are irrelevant, and definitely interfere with cranking.
PinkElephant
4.8 / 5 (6) Apr 01, 2011
@Decimatus,
the expected age of the universe is such that most stars form from some kind of supernova waste
What are the MEASURED relative element abundances in the universe? By mass fraction: 74% hydrogen, ~24% helium. Everything else added together: ~2%.

http://en.wikiped...Universe
Logically, the Sun has to have some large core of heavy elements, making up a high fraction of it's total mass.
How is that logical? The Sun is 99.86% of the solar system's mass. Its composition reflects the contents (and metallicity) of the protostellar nebula which gave birth to it. Why should that nebula have differed so drastically from the rest of the universe?

http://en.wikiped...tructure
Take the planets for example
Which ones? The giant gas bags, or the tiny rocky specks and asteroids that couldn't hold on to H/He gravitationally, so it all blew away when the Sun ignited?
PinkElephant
5 / 5 (6) Apr 01, 2011
ctd.

The Sun's average density is measured at just ~1.4 times that of ordinary water at room temperature and pressure.

http://nssdc.gsfc...act.html

Considering the Sun's powerful gravity and large volume, most of its gaseous content is quite dense, even long before you get closer down to the core (where the pressures reach billions of atmospheres.) What room do you see for there being any significant concentrations of heavy elements, while keeping the Sun's overall density (as ratio of mass to volume) what is actually is?
the theories usually state that elements beyond FE can not be created through normal stellar fusion
In bulk terms, that's right. It has to do with whether a given fusion reaction yields any energy, or actually soaks up energy. The moment a massive star can no longer generate sufficient energy at its core, it collapses and its outer layers blow away in a supernova. E.g. see here:

http://en.wikiped...ron_peak
that_guy
5 / 5 (1) Apr 02, 2011
@pinkElephant

5 Stars. You're on a roll today.
Quantum_Conundrum
2 / 5 (4) Apr 02, 2011
In bulk terms, that's right. It has to do with whether a given fusion reaction yields any energy, or actually soaks up energy. The moment a massive star can no longer generate sufficient energy at its core, it collapses and its outer layers blow away in a supernova. E.g. see here:


Except that I've already proven mathematically exactly what happened to the Crab Nebula's missing mass, and it was not and cannot be any form of "Nuclear Fusion". Roughly 1/4 to 1/3rd of the mass ended up in the Neutron Star, a further 1/3rd ended up in the expanding nebula which is well above the escape velocity of the gravity well of the Neutron Star and the Cloud's mass combined, and the remaining 1/3rd of the original mass was completely annihilated in a matter-anti-matter annihilation. The math works so perfectly as to be almost completely beyond any chance of coincidence.

Nuclear Fusion alone is not capable of producing the energy levels needed to obtain escape velocity from a 10M star.
Shootist
not rated yet Apr 02, 2011
Pair instability super nova?
Shootist
not rated yet Apr 02, 2011
edit doesn't work.

But no that doesn't leave behind a neutron star. Are you suggesting some kind of pair instability/core collapse super nova?
PinkElephant
3.7 / 5 (3) Apr 03, 2011
edit doesn't work.
I found the workaround is to reload the page. After that, when hitting "edit" the "Submit" button is no longer greyed out. Of course, the 3-minute editing window still applies, so if you reload after 3 minutes from posting, you won't any longer have the option to edit.
Are you suggesting...
With QC, the suggestion typically is that he's a genius and everyone else (including the experts in the field) is an idiot. Of course, in his above post there are so many nakedly nonsensical statements, that personally I don't even have any desire to respond to it...
Quantum_Conundrum
1 / 5 (2) Apr 03, 2011
edit doesn't work.

But no that doesn't leave behind a neutron star. Are you suggesting some kind of pair instability/core collapse super nova?


What I suggested was that when the neutron star is forming as the core collapses, particle collisions caused by the insane gravity well fuse a huge amount of the remaining materials to Neutrons (but some of it ends up as anti-neutrons, which you'll need to check google and wikipedia about how that happens.) Once this happens, the anti-neutrons annihilate with the nuetrons.

Additionally, the nuclear chemistry for it all actually works, in theory, accurate to within a fraction of a solar mass, producing a total annihilation and precisely the amount of energy needed to overcome the gravity of the Crab and end up with the 1500km/s velocity of the expanding nebula.

In addition, you can figure the apparrent brightness of the crab from the historical record and use this plus the inverse square law to calculate how much energy...
Quantum_Conundrum
1 / 5 (2) Apr 03, 2011
...to calculate how much energy escaped the star and the nebula as visible light during the years immediately following the explosion. The visible light came from the gamma rays being absorbed and re-emitted inside the cloud over and over, until some of it escaped.

When you do the math, which I did on the main forum a couple months ago, you find that the amount of energy released from the crab can only be consistent with it's observed brightness if it was indeed a matter-antimatter annihilation, as nuclear fusion, even total fusion of all matter to the heaviest elements, could not have produced that much energy to appear so bright from such a distance.
RobertT
5 / 5 (1) Apr 03, 2011
Wikipedia?

... ha ha ha ....
omatumr
1 / 5 (4) Apr 03, 2011
a.) a neutron star cannot in principle have a mass smaller than 1.08 solar masses, . . .

b.) existing knowledge and data are irrelevant, and definitely interfere with cranking.


a.) The lower mass limit of 1.08 solar masses does not consider neutron repulsion.

Neutron repulsion causes neutron stars to emit neutrons. Neutrons "evaporate" from the surfaces of neutron stars as water evaporates from the surface of water.

www.youtube.com/w...yLYSiPO0

b.) Here are some experimental data that you ignore:

www.omatumr.com/D...Data.htm

www.omatumr.com/D...ata1.htm

www.omatumr.com/D...Data.htm

www.omatumr.com/D...Data.htm

www.omatumr.com/D...Data.htm

www.omatumr.com/D...Data.htm

www.omatumr.com/i...Fig2.htm

www.omatumr.com/i...Fig1.htm

www.omatumr.com/i...Fig3.htm

www.omatumr.com/i...Fig4.htm

omatumr
1 / 5 (4) Apr 03, 2011


The Sun's average density is measured at just ~1.4 times that of ordinary water at room temperature and pressure.

http://nssdc.gsfc...act.html


We addressed this misinformation in "Earth's Heat Source - The Sun" [Energy & Environment 20 (2009) 131.

http://arxiv.org/pdf/0905.0704

"Densities within the Sun span many orders of magnitude. The average overall density of the Sun, which depends on both internal structure and composition, may be as meaningless as the average overall density in the Rutherford-Bohr model of the atom."

"The solar density is about 10^-6 g/cm^3 in the photosphere, and the density of material
in the nuclear solar core is at least equal to that of the atomic nucleus, ~10^+15 g/cm^3.
The Sun extends outward about 100 AU above the photosphere and has an average
overall density of about 1.4 x 10^-13 g/cm^3."

PinkElephant
3.7 / 5 (3) Apr 04, 2011
Neutron repulsion causes neutron stars to emit neutrons.
Oh but what magical force keeps the Sun's "mostly iron" interior from collapsing onto its neutron star core, which has typical escape velocity of ~100,000 km/s (i.e. 1/3 the speed of light)? And where did all that iron in the Sun come from: fairy dust?
The average overall density of the Sun, which depends on both internal structure and composition, may be as meaningless as the average overall density in the Rutherford-Bohr model of the atom
Oh really? The Sun is mostly empty space? This just gets better and better.
The solar density is about 10^-6 g/cm^3 in the photosphere...
You're the one claiming that the Sun's composition is mostly Fe. Is Earth's orbit determined by the photosphere, or the OVERWHELMING BULK of the Sun's mass located beneath the photosphere?

Earth's density is almost 4 times higher than that of the Sun. And they're made of similar stuff, which means I'm an actual pink elephant.
omatumr
1 / 5 (2) Apr 10, 2011
Earth's density is almost 4 times higher than that of the Sun. And they're made of similar stuff, which means I'm an actual pink elephant.


No.

Read the information just above your post:

"The Sun extends outward about 100 AU above the photosphere and has an average overall density of about 1.4 x 10^-13 g/cm^3."

Earth's density is greater than the Sun's density by a factor of ~40,000,000,000,000.

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