Chandra finds superfluid in neutron star's core

Feb 23, 2011
This image presents a beautiful composite of X-rays from Chandra (red, green, and blue) and optical data from Hubble (gold) of Cassiopeia A, the remains of a massive star that exploded in a supernova. Evidence for a bizarre state of matter has been found in the dense core of the star left behind, a so-called neutron star, based on cooling observed over a decade of Chandra observations. The artist's illustration in the inset shows a cutout of the interior of the neutron star where densities increase from the crust (orange) to the core (red) and finally to the region where the "superfluid" exists (inner red ball.) Credit: X-ray: NASA/CXC/UNAM/Ioffe/D.Page,P. Shternin et al; Optical: NASA/STScI; Illustration: NASA/CXC/M. Weiss

(PhysOrg.com) -- NASA's Chandra X-ray Observatory has discovered the first direct evidence for a superfluid, a bizarre, friction-free state of matter, at the core of a neutron star. Superfluids created in laboratories on Earth exhibit remarkable properties, such as the ability to climb upward and escape airtight containers. The finding has important implications for understanding nuclear interactions in matter at the highest known densities.

Neutron stars contain the densest known matter that is directly observable. One teaspoon of neutron star material weighs six billion tons. The pressure in the star's core is so high that most of the charged particles, electrons and protons, merge resulting in a star composed mostly of uncharged particles called neutrons.

Two independent research teams studied the supernova remnant Cassiopeia A, or Cas A for short, the remains of a massive star 11,000 light years away that would have appeared to explode about 330 years ago as observed from Earth. Chandra data found a rapid decline in the temperature of the ultra-dense neutron star that remained after the supernova, showing that it had cooled by about four percent over a 10-year period.

"This drop in temperature, although it sounds small, was really dramatic and surprising to see," said Dany Page of the National Autonomous University in Mexico, leader of a team with a paper published in the February 25, 2011 issue of the journal Physical Review Letters. "This means that something unusual is happening within this neutron star."

Superfluids containing charged particles are also superconductors, meaning they act as perfect electrical conductors and never lose energy. The new results strongly suggest that the remaining protons in the star's core are in a superfluid state and, because they carry a charge, also form a superconductor.

"The rapid cooling in Cas A's neutron star, seen with Chandra, is the first direct evidence that the cores of these neutron stars are, in fact, made of superfluid and superconducting material," said Peter Shternin of the Ioffe Institute in St Petersburg, Russia, leader of a team with a paper accepted in the journal Monthly Notices of the Royal Astronomical Society.

Both teams show that this rapid cooling is explained by the formation of a neutron superfluid in the core of the neutron star within about the last 100 years as seen from Earth. The rapid cooling is expected to continue for a few decades and then it should slow down.

"It turns out that Cas A may be a gift from the Universe because we would have to catch a very young neutron star at just the right point in time," said Page's co-author Madappa Prakash, from Ohio University. "Sometimes a little good fortune can go a long way in science."

The onset of superfluidity in materials on Earth occurs at extremely low temperatures near absolute zero, but in neutron stars, it can occur at temperatures near a billion degrees Celsius. Until now there was a very large uncertainty in estimates of this critical temperature. This new research constrains the critical temperature to between one half a billion to just under a billion degrees.

Cas A will allow researchers to test models of how the strong nuclear force, which binds subatomic particles, behaves in ultradense matter. These results are also important for understanding a range of behavior in neutron stars, including "glitches," neutron star precession and pulsation, magnetar outbursts and the evolution of neutron star magnetic fields.

Small sudden changes in the spin rate of rotating neutron stars, called glitches, have previously given evidence for superfluid neutrons in the crust of a neutron star, where densities are much lower than seen in the core of the star. This latest news from Cas A unveils new information about the ultra-dense inner region of the neutron star.

"Previously we had no idea how extended superconductivity of protons was in a neutron star," said Shternin's co-author Dmitry Yakovlev, also from the Ioffe Institute.

The cooling in the Cas A neutron star was first discovered by co-author Craig Heinke, from the University of Alberta, Canada, and Wynn Ho from the University of Southampton, UK, in 2010. It was the first time that astronomers have measured the rate of cooling of a young neutron star.

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User comments : 31

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Cave_Man
2.2 / 5 (16) Feb 23, 2011
Sounds like a giant space organism, analogous to a stellar brain, but then again the universe looks like a network of neurons on the large scale so I've already begun to assume everything is "alive" down to the rocks and dirt.
kaasinees
3.1 / 5 (17) Feb 23, 2011
The neutron expulsion guy must get a boner from this.

@Cave_Man You must like the Gaia Theory, do you know it?
antialias
4.2 / 5 (11) Feb 23, 2011
Sounds like a giant space organism, analogous to a stellar brain, but then again the universe looks like a network of neurons on the large scale so I've already begun to assume everything is "alive" down to the rocks and dirt.

Doctrine of signatures? Sometimes analogies can be taken too far. You have taken yours beyond the illogic horizon and haven't stopped accelerating.
frajo
4.5 / 5 (10) Feb 23, 2011
A lot of buzzwords but nowhere a plausible hint how they got their conclusions.
It's not amusing when PhysOrg readers are confused with YellowPress readers.
Terrible_Bohr
4.2 / 5 (9) Feb 23, 2011
330 is a very precise measurement. It makes me wonder: how does one determine a neutron star's age, anyway?
omatumr
2.3 / 5 (16) Feb 23, 2011
Readers may want to scan the paper and the references cited in "Superfluidity in the solar interior: Implications for solar eruptions and climate" [ Journal of Fusion Energy 21 (2002) 193-198]

arxiv.org/pdf/astro-ph/0501441v1

With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo
omatumr
2.3 / 5 (15) Feb 23, 2011
The neutron expulsion guy . . .


Neutron repulsion causes neutron expulsion.

"Neutron Repulsion"
The APEIRON Journal
in press (2011), 19 pages
arxiv.org/pdf/1102.1499v1

pauljpease
4.8 / 5 (11) Feb 23, 2011
330 is a very precise measurement. It makes me wonder: how does one determine a neutron star's age, anyway?


Neutron stars form as a result of a supernova. Thus, if you can figure out when the star exploded, you know how old the neutron star is. This supernova was observed on Earth 330 years ago, so was witnessed by humans in the year ~1681 AD, and someone wrote down the observation, so we know exactly when this particular neutron star formed.
yyz
5 / 5 (12) Feb 23, 2011
@pauljpease:

While several galactic supernova have been observed in the past (Tycho, Kepler, etc), Cassiopeia A wasn't one of them.

The remnant was discovered at radio wavelengths in 1947 followed by optical detection in 1950. Measurements of the expansion of the remnants point to a date around 1680 for the supernova.

(there is a possible detection of the supernova by Flamsteed in 1680, though)

A light-echo of the supernova was detected recently by the Spitzer telescope, the first infrared echo observed from a supernova.

The age of the SN determined by the light echos was consistent with the previous age estimates.
Terrible_Bohr
5 / 5 (11) Feb 23, 2011
Ok, so there's a less obvious way to date a neutron star than simply observing it's formation: measuring the distance of the explosion's remnants. Good to know; thanks!

If the pitiful act of asking a question is worthy of a downrate, surely the weakness implicit in gratitude will also merit one. Click away, Thermodynamics.
TehDog
5 / 5 (7) Feb 23, 2011
Meh, both posts get a five from me. Downvoting summat like TB's post is grudge behaviour :(
xyz, pp, thanks also :)
omatumr
2 / 5 (12) Feb 23, 2011
Ok, so there's a less obvious way to date a neutron star than simply observing it's formation: measuring the distance of the explosion's remnants. in gratitude will also merit one. Click away, Thermodynamics.


The date of the local supernova that gave birth to the solar system was determined by combined age dating using two actinide elements, U (uranium) and Pu (plutonium).

That combined age-dating method indicated that a supernova made our actinide elements about 5 billion years ago [See Fig. 1, p. 173 of "Plutonium-244 fission xenon in the most primitive meteorites," Radiochimica Acta 64 (1994) 167-174].

adsabs.harvard.edu/abs/1994RadAc..64..167K
Shelgeyr
1.8 / 5 (18) Feb 23, 2011
Chandra finds superfluid in neutron star's core

No it didn't. Not by a long shot.

Evidence for a bizarre state of matter has been found in the dense core...(snip)...has discovered the first direct evidence for a superfluid (snip) at the core of a neutron star. (snip) Neutron stars contain the densest known matter that is directly observable.


These are 100% untrue statements when presented as scientific facts, violently abusing the terms "found", "discovered", "direct evidence", and "directly observable". At best - at BEST - these statements are blatant opinions... speculative hypotheses meant to explain the images Chandra has provided. At worst, the statement that "evidence 'for a bizarre state of matter' has been FOUND in the dense core" is fraudulent. They "found" nothing "in the core", much less evidence of what might be there (or even if there is a "there" there).

Why must they dress up "speculation" so? They've turned amazing data into bad science.
vidar_lund
4.8 / 5 (9) Feb 23, 2011
Chandra finds superfluid in neutron star's core

No it didn't. Not by a long shot.

It wasn't very clear from the article but I think the point is that the rapid cooling of the neutron star is hard to explain without some very powerful mechanism for heat transfer from the interior to the exterior of the neutron star. A superfluid superconducting core sounds like a very effective heat transmitter to me but I'm not by any means an expert on this.
barakn
3.9 / 5 (12) Feb 24, 2011
The date of the local supernova that gave birth to the solar system was determined by combined age dating using two actinide elements, U (uranium) and Pu (plutonium).

That combined age-dating method indicated that a supernova made our actinide elements about 5 billion years ago [See Fig. 1, p. 173 of "Plutonium-244 fission xenon in the most primitive meteorites," Radiochimica Acta 64 (1994) 167-174].

adsabs.harvard.edu/abs/1994RadAc..64..167K
Don't be modest, the abstract says MORE than 5 billion years, which is substantially earlier than the 4.56 billion years measured in other meteorite inclusions. This suggests that material from multiple supernovae mixed together to form the solar system, which goes directly against your thesis that the solar system is formed from the remnants of just one supernova. If you were smart you'd quietly expunge any mention of this paper from your website and papers.
omatumr
2.4 / 5 (10) Feb 24, 2011
Thanks, barakn.

The oldest meteorite inclusions are also ~5 billion years. Please see the data points themselves here:

omatumr.com/Data/1994Data.htm
barakn
4 / 5 (9) Feb 24, 2011
The data points are artificial, as one entire axis is not of a measured quantity but of a derived quantity. Got anything better than that?
gwrede
4 / 5 (4) Feb 24, 2011
Shelgeyr wrote:
...statements when presented as scientific facts, violently abusing the terms "found", "discovered", "direct evidence", and "directly observable".
I have to agree to a certain extent. The article presents measurements that fit a theoretical model as hard facts. It also takes liberties with tone and grade that are not consistent with good scientific presentation.

The authors come out as arrogant, sloppy and corner-cutting people who jump to premature conclusions. Good science is nothing like that.
omatumr
1.9 / 5 (9) Feb 24, 2011
The data points are artificial, as one entire axis is not of a measured quantity but of a derived quantity. Got anything better than that?


No. Data points show the (Pu-244/U-238) ratio on the vertical scale. The horizontal scale simple shows you when the (Pu-244/U-238) ratio had that value.

Oliver K. Manuel
barakn
3.7 / 5 (6) Feb 24, 2011
So your graph is mislabeled.
barakn
4 / 5 (8) Feb 24, 2011
And just how is it that the exact same graph appears here: omatumr.com/summary/figure2.html
but with Th replaced by U-235 in the title and Xe-136 and Pb-206,207 showing up in the subtitle? Clearly one of these graphs is mislabeled.
omatumr
1.9 / 5 (8) Feb 24, 2011
You are right, barakn.

Th, U and Pu are three radioactive actinide elements that were present in the early solar system.

Two isotopes of uranium, U-235 and U-238, are used in U-Pb age dating.

One isotope of plutonium, Pu-244, is used in Pu-Xe age dating.

These two methods were combined by Kuroda and Myers.

The two graphs are, in fact, identical, but Th should not have been in the title.

Thanks for pointing that out!

While I have your attention, can I ask you to comment on the neutron star at the Sun's core: "Neutron Repulsion" [The APEIRON Journal, in press (2011) 19 pages]

arxiv.org/pdf/1102.1499v1

A2G
1.5 / 5 (8) Feb 27, 2011
I agree with others here. There is no proof that what this article put forth is verifiable at all. This is nothing more than speculation as to what might be going on in this so-called supernova remnant. I say so-called supernova remnant because it is also speculation that this formation in space came about because of the explosion of a star many years ago. But the wave front velocity of this so-called explosion does not match up to what would be found if this was truly a star that exploded. This exploding star theory is only assumed to be correct, but not provable. It is speculation, just as this article is. Keeps the funding coming in though.
lomed
5 / 5 (1) Feb 27, 2011
arxiv.org/pdf/1102.1499v1
I know I am not barakn, but I decided I would have a look at the paper. There seem to be two questions that I find myself asking: How do you explain the muon and tau neutrinos that the Sun emits (you mention the observations at the Sudbury observatory but seem to dismiss them as irrelevant)? Can the emission rate of neutrons be determined theoretically (so that one can determine the lifetime of a neutron star with a given mass)?
omatumr
1 / 5 (4) Feb 27, 2011
[ q] "Neutron Repulsion": arxiv.org/pdf/1102.1499v1


1. How do you explain the muon and tau neutrinos that the Sun emits (you mention the observations at the Sudbury observatory but seem to dismiss them as irrelevant)?

2. Can the emission rate of neutrons be determined theoretically (so that one can determine the lifetime of a neutron star with a given mass)?

Thanks for your comments.

1. Later research showed that the electron, muon and tau neutrinos cannot directly oscillate into each other. There would have to be a fourth type of neutrino, the "sterile" neutrino. I think that I referenced that finding in the paper.

2. Yes, we can and have used solar luminosity and the measured flux of electron neutrinos to estimate the lifetime of the neutron star at the core of the Sun. Those results have not yet been published.

Thanks for taking the time to read and comment on the paper.

With kind regards,
Oliver K. Manuel
jsa09
5 / 5 (1) Feb 28, 2011
Chandra finds superfluid in neutron star's core

No it didn't. Not by a long shot.

It wasn't very clear from the article but I think the point is that the rapid cooling of the neutron star is hard to explain without some very powerful mechanism for heat transfer from the interior to the exterior of the neutron star. A superfluid superconducting core sounds like a very effective heat transmitter to me but I'm not by any means an expert on this.


A super insulator would be just as good an explanation, except we don't know of any examples yet.
ZephirAWT
Mar 01, 2011
This comment has been removed by a moderator.
GSwift7
1.7 / 5 (3) Mar 04, 2011
@ Shelgeyr:

evidence 'for a bizarre state of matter' has been FOUND


They said they found evidence. That's a fair statement I think.

@ lomed:

I know I am not barakn


lol, taken out of context, we could have a lot of fun with that statement. Can you provide evidence with error bounds? What is the chance that you are mistaken and that in reality you are Barakn! OMG!! Many people with mental illness like accute personality disorders are unaware that they have a problem, you know. :)
lomed
5 / 5 (1) Mar 05, 2011
statement...I think...taken out of context...fun...is...with...accute...disorders..., you know. :)
Amazing the things you can make people say with quotes.
What is the chance that you are mistaken and that in reality you are Barakn!
You seem to answer yourself with:
Many people with mental illness like accute personality disorders are unaware that they have a problem
So, since the second quote implies any response by me would be inconclusive, you must be talking to yourself, which can only mean...personality disorders all around!

By the way, the designation of the Arxiv article associated with this Physorg article is:
1011.6142v2 [astro-ph.HE]
Shelgeyr
1.6 / 5 (7) Mar 05, 2011
GSwift7, they claim to have found "evidence" of what it is like at the core of a neutron star. No. They interpreted the observed cooling as being applicable to the core (an assumption) of a neutron star (another assumption well skip for now), then acting as if their assumptions were true, worked backwards and decided it must mean the core is in a superfluid state (another assumption). Then they say this:
Superfluids containing charged particles are also superconductors, meaning they act as perfect electrical conductors and never lose energy.

Notice that this is simply asserted as fact. A "given". It is NOT a fact. It is not even a theory because there is no evidence of its truth, it hasn't been formulated (although that would be an interesting and potentially very profitable challenge), there does not exist a superconducting superfluid anywhere on Earth, and it is NOT testable. At best it's a hypothesis. This tissue of assumptions does not support the claim of discovery.
lomed
5 / 5 (2) Mar 05, 2011
there does not exist a superconducting superfluid anywhere on Earth, and it is NOT testable. At best its a hypothesis. This tissue of assumptions does not support the claim of discovery.
I think the combination of these two properties may have been a mistake of the author of the Physorg article. As far as I can tell there was no such claim in the original paper (assuming the paper I found was the original), and that section is not in quotes.
neutron stars are, in fact, made of superfluid and superconducting material," said Peter Shternin
I can see how this statement could be misconstrued to say that the same material is both superconducting and a superfluid. However, the paper indicates the model they use predicts that the relatively small number of protons superconduct, and the neutrons are a superfluid. The attitude of the paper seems to be optimistic that the observed cooling validates their models, but that it will take several more years of observations to be sure.
Shelgeyr
1.6 / 5 (7) Mar 06, 2011
Iomed, while I certainly think the author is mistaken, I don't think they made a mistake, i.e. I don't think they misinterpreted the material from which this article was written.

I obviously don't know this to be true, but I base my supposition on another physorg.com article which says in part:
Separately, the two phenomena are well understood. A superconductor allows a flow of current without resistance. Similarly, a superfluid flows without friction. Unlike superconductors and superfluids, a superfluid-superconductor does not exist on earth. But, understanding its hybrid behavior may be a first step toward creating one in the lab and understanding what goes on inside neutron stars.

The URL for this other article is physorg.com/news136863422.html and this quote is the fourth paragraph.

So I think they mean it... I also think they're wrong.

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