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Astronomers discover the most massive neutron star

The discovery has wide implications for astrophysics and nuclear physics

The signals from the pulsar (behind) pass by a white dwarf and are amplified. Illustration: National Radio Observatory
The signals from the pulsar (behind) pass by a white dwarf and are amplified. Illustration: National Radio Observatory

Astronomers have discovered through the Green Bank Telescope (GBT) the most massive neutron star ever discovered, a discovery that has far-reaching implications for several fields in physics and astrophysics.

The research was carried out by Paul Demorest and Scott Ransom fromThe National Observatory for Radio Astronomy [[National Radio Astronomy Observatory (NRAO), along with Tim Panucci of the University of Virginia, Mallory Roberts of Eureka Scientific, and Jason Hassells of the Netherlands Institute for Radio Astronomy and the University of Amsterdam. It was published on October 28 in the scientific issue of the journal Nature. The preliminary article was published here.

Demorest said, “This neutron star is twice as massive as our Sun. This is a surprising discovery, and such an amount of mass means the negation of several theoretical models that now describe the internal composition of neutron stars." He added, "Measuring this mass also has implications for our understanding of all matter at extremely high densities and many details of nuclear physics."

Neutron stars are supernuclear cores of massive stars that exploded in a supernova process. A valve packed into the size of a sphere the size of a small city, with their protons and electrons squashed together into the neutrons. A neutron star can be many times more dense than an atomic nucleus, and a speck of material from a neutron star would weigh more than 500 million tons. This enormous density makes neutron stars an ideal natural laboratory for studying the most exotic and densest states of matter known to physics.

The scientists used a well-known effect from Einstein's theory of general relativity, known as The Shapiro delay effect, to measure the mass of the neutron star and its orbiting companion, a white dwarf star.

The neutron star is a pulsar that emits radio waves in pulses into space as it spins. This pulsar is called: PSR J1614-2230 and it rotates 317 times per second while its partner completes an orbit in nine days. The pulsar pair and the white dwarf are located at a distance of 3000 light years from us, they are in an orbit that appears almost perpendicular to the Earth. This orientation was the key to performing the mass measurement using the Shapiro delay effect.

While the orbit takes the white dwarf directly in front of the pulsar, the radio waves reaching Earth from the pulsar have to travel very close to the white dwarf. This close journey causes them to be delayed in reaching Earth due to the space-time distortion caused by the white dwarf's gravity. It's the Shapiro delay effect that allowed scientists to accurately measure the mass of the two stars.

The astronomers used a new digital device calledGreen Bank Ultimate Pulsar Processor Device” [Green Bank Ultimate Pulsar Processing Instrument (GUPPI)]. This instrument followed the binary stars this year as they made one complete orbit. Using the GUPPI the astronomers could measure the signals from the pulsar several times better than before.

The researchers expected the neutron star to have a mass that is about one and a half times that of the Sun. But instead, their observations revealed that its mass was twice that of the Sun. This enormous amount of mass already completely changes the understanding of neutron star composition.

Some theoretical models state that, in addition to neutrons, such stars will contain additional exotic subatomic particles called hyperons or clusters of kaons. Ransom said that the new results about the neutron star refute these assumptions.

The results of the study also show that if any quarks are present in the core of the neutron star, they cannot be "free," but instead must interact strongly with each other as they do in ordinary atomic nuclei, says Priel Ozal of the University of Arizona, author of another paper. on the subject, which the authors plan to publish in the Astrophysical Journal Letters.

The new research and observations carried out with the help of GBT have additional implications for other fields, beyond the characterization of matter at extreme densities. The fact that neutron stars can be as massive as the one discovered named PSR J1614-2230 could shed light on neutron star collisions, which are expected to produce gravitational waves; The latter are the target of a number of observations that operate in the US and Europe. According to the scientists, these waves will carry additional valuable information about the composition of the neutron stars.

For information on the World Radio Observatory website

For news in Science Daily

36 תגובות

  1. Zarathustra,

    The rotation of Kadaha around itself is indeed slowed down by the influence of the tidal forces of the moon:
    In the same way, the rotation time of a pulsar may also be slowed by tidal forces.
    When the scientists on whose behalf you have already decided that there are no gravitational waves present their paper, it will be worthwhile to discuss corrections to general relativity and it is likely that, like many good ones, they are also wrong - for now you have not presented more than a rumor here.

    By the way, in the book E=mc^2 (Nigel Conder) there is a nice chapter that deals with this very subject and explains why scientists are convinced of the existence of gravitational waves (this is the way bodies know about the change of position of massive bodies that are near them) - as well as the great difficulty in detection .

  2. Zarathustra:
    I don't know why you're talking about a watch and what it has to do with us.
    I also don't know what you want me to explain to you, but I know what explanation you need at this stage of your life, and it's not an explanation about pulsar clocks, but an explanation about how to study science.
    In science there is no possibility to start straight from the university. You need to understand some basic things first.
    You do not have the basis and it is not possible to explain anything else to you at this point.
    The point is that your attitude towards the subject also prevents you from learning the basics.

  3. Machel
    I mean the change in the pulser frequency.
    And if you know, explain if the frequency slows down, how can you tell that this is the result of a tide.
    And in what cases it will accelerate.

  4. Zarathustra:
    I don't know why you are talking about a watch. It has nothing to do with us.
    If you understand my explanation you will be able to tell the difference between one binary pair and another.
    All of them have tidal forces and the manner of their influence is, as I said, a result of the position of each of them in relation to the synchronous orbit of the other.
    In general, the argument "I don't know how to do this and that" can only support the writer's claim of ignorance. He cannot support any other claim and certainly not a claim that contradicts the claims of those who are indeed experts in the field in which the writer claims ignorance.
    I know this is a complex sentence, so please concentrate.

  5. Machel
    I don't claim to be as knowledgeable in the field as you are, but these researchers surely knew how to point out the source of the difference between speeding up and slowing down the clock. After your explanation I won't be able to tell the difference between one binary pair and another. Why are there tidal forces here and not here?

  6. And it has already been explained to you many times that the above distance has a very good reason in the form of tidal forces (or are you proposing to eliminate this part of physics as well?)

  7. deer
    Everything you wrote is agreed upon and I do not pretend to an alternative theory. but…
    A paper is due out by researchers who have found examples of binary stars that demonstrate a change in the opposite direction of the pulsar clock as I mentioned above at the beginning.
    This may present a small problem with the theory.

  8. Zarathustra,

    I am tired of discussing with you, I have no doubt that you are not interested in learning anything but only repeating your mantra over and over again.
    Systematic changes of cycle times in neutron stars is very significant and this is due to their tremendous level of precision - therefore saying a few millionths is a lot on the scale of neutron stars.

    If you are so right, propose an adequate mechanism that will produce the same effect (for details) - make a calculation and propose it to a scientific monthly. If you succeed in contradicting all the experts (who were happy to succeed in discovering such a significant mistake), you will surely gain world fame and I will cry for not stealing from you the discovery that would surely have guaranteed me a coveted professorship.
    As far as I'm concerned - NASA, the Nobel Prize committee and every physics professor I've heard of are sufficient authority.

  9. deer
    It is clear and known to everyone that gavitational projection is a fundamental component of general relativity.
    and yet….
    Measuring a change in the pulsar's clock over several years which is less than a millionth of the lifetime of the binary orbit. and conclude that this is due to gravitational radiation. And not because of another possible residual effect from another body???
    It is not clear where this confidence comes from?
    When at stake are dark matter and energy that we don't know much about.
    It is possible that when the lot is removed from these mysteries it will be necessary to update some things in the general relationship.

  10. Khaizarathostra:
    I'm writing this comment only because I like puns.
    I have already convinced myself that there is nothing to continue talking to you.

  11. Zarathustra,

    As I have already said a million times - the detectors that have been built to date are weak relative to what is required and were not expected to detect gravitational radiation except from unusual events - which simply did not occur. Therefore, it is not surprising that nothing was discovered.
    Your explanation is far more puzzling and strange and requires a lot of coincidences -
    The simple thing is to assume that the theory of relativity (which has already been proven in countless tests) is also true in this prediction which simply has not been tested yet because the Galen are too weak.

    Since you can continue to claim that you are right even though you have never studied general relativity (which you will do as expected) - try for a change to give a quote from Mishno who knows general relativity at a reasonable level and who maintains that gravitational radiation is a questionable thing.

    I'll save you some searching:
    The Nobel Prize Committee in Physics and NASA (which approved the expansion of the LISA project at enormous cost) do not agree with you - neither does Wikipedia, whose entry on the subject does not include any sub-entry on the subject of "disputes regarding the existence of gravitational radiation".

  12. Machel
    If you prefer to assume that these pulsars are spinning in empty space isolated from any gravitational influence.
    Ok so aliens also exist.

  13. Zarathustra:
    I think the chance is almost 100%.
    By the way - in your opinion, what is the probability that an electron exists?
    Has anyone seen an electron?
    Almost everything important in nature is detected by indirect measurements - that is - by its effect on other things and the indirect effect of gravitational waves on the orbits of the stars is a very strong evidence.
    But you have already convinced me of one thing and that is that there is no way to convince you: the entire scientific community can think A and you will still argue passionately and confidently (and without any reasoning!) Q B.

  14. Zvi Machal
    What is the chance that the orbit of the binary pair is not affected by additional gravity versus the chance that gravitational waves exist. When all the detectors built to date gave negative results.
    This does not justify the solution even if it is more convenient and simpler.
    In the same way you can assume that there are aliens that are responsible for the appearance of life.
    Many problems have simple solutions assuming you're willing to take the plunge.

  15. I have already had this argument for a long time.
    There is a simple theory that explains the phenomena in a precise way and you can see all the calculations in it and argue about it. Zarathustra offers a complicated theory that he doesn't even try to show how it explains the results but expects us to be convinced.
    Maybe we should stop wasting our time?

  16. The shift of the perihelion is not an orbital resonance by definition - in any case this debate is not important because the shift of the perihelion does not mean a change in the cycle time/characteristic distance between bodies anyway.

    A black hole is a very, very difficult requirement - remember that these are not distant bodies at all, since otherwise the gravitational radiation between them would be negligible (its intensity is paraproportional to the distance by (5-):

    In this case, their distance is 2 million km - about 100 times closer than the distance of the Sun from Earth

    Note that it took 19 years to award a Nobel Prize for this so someone would have thought about tilting the plane of observation if it was important - in this case it is not important because what is measured are changes in cycle time.

    As for Ockham's razor.
    If you look at the moon and don't see the US flag there, it would be wrong to believe that you don't see it because aliens abducted it or that the US faked the landing there - it is much more likely to understand that the device in your hand (eye in this case) is not sharp enough to notice a small flag from such a great distance.
    The same is true in the case of gravitational radiation - even according to the theory we were not supposed to discover it yet, this does not mean that it is not there and especially when its prophecies are so successful

  17. deer
    In addition, it must be remembered that in the universe you will not find a separate binary track free of influences.
    All orbits are always more than two bodies, especially when it comes to bodies with a mass that is twice that of one sun or more.
    The black hole that affects all binary stars is at the center of every galaxy and it is certainly possible that it has the same residual effect on a binary pair.
    that you give the solutions obtained.

  18. deer
    The deviation of the perihelion or orbital tilt is essentially an orbital resonance and one of the first proofs of the difference between relativistic and Newtonian calculations.
    A black hole located at a suitable point will cause a resonance that will give identical solutions.
    Remember that these are very distant bodies.
    I meant the inclination of the binary orbital plane relative to the observation point from Earth.
    When there is a possibility of solutions based on physical laws that have empirical proofs and on the other hand those that do not. According to Okam, it is advisable to choose the former.

  19. Zarathustra,
    How many points:

    1. Note that none of the solutions you proposed talks about a two-body problem (two neutron stars) but requires that the problem be three-body - this is contrary to what has been observed - although they may not have seen the black hole, or the object that makes an orbital resonance - but this already requires Explanation (How come a massive object like a black hole does not affect anything at first order and only creates a residual effect of convergence?).

    2. Your statements regarding the planet Hema are confused and incorrect - orbital resonance is a classical effect and not a relativistic one. The planet Mercury has a relationship between the length of the day and the length of the year as a result of the interaction with the Sun (3 to 2 ratio). Other effects of orbital resonance are related to other stars (three-body problem) - besides, the planet Hema has a shift of the perihelion due to a relativistic effect - but this is not related.

    3. "Tends towards a ball" is a very misunderstood concept

    Anyway, the gist of it is this:
    There is a scientific prediction (gravitational waves) based on a proven and very successful theory (general relativity) which predicts results in an astrophysical system (a pair of neutron stars). Instead of accepting this, you insist that maybe the theory is wrong (despite all its evidence) and therefore the prediction is also wrong and the fact that the prediction comes true is just a coincidence resulting from countless other coincidences that led to a cumulative effect identical to the effect of the wrong prediction.
    In this way, you could say that the fact that every time a lamp turns on, it is not because I closed an electrical circuit, but because just then a small piece of sunlight flew (due to the solar wind of course) and entered the lamp just in time to create the illusion that it was the pressing of the switch that turned on the lamp.

  20. deer
    There are many mechanisms that can be thought of for example the effect of a black hole in the environment of the binaries.
    Orbital resonance is a very common phenomenon in all celestial bodies.
    Such a resonance exists because of a relativistic effect between only two bodies such as the planet Mercury.
    It is possible that the orbital plane of the measured binaries is inclined to a sphere in such a way that the changes in the orbital resonance reflected the solution for which the Nobel Prize was awarded.
    While it is generally a solution of an orbital resonance section.

  21. Zarathustra,

    It's nice that you say "a system that oscillates between two short and long tracks"
    But such a statement without proposing a physical mechanism is meaningless - orbits do not oscillate just like that.

    The point is that tidal forces - as Michael said tend to transfer angular momentum from the individual stars to the orbit and therefore there is a drift (this is an irreversible process, as it results from friction within each of the bodies).

    The convergence process cannot be explained by any known non-relativistic mechanical mechanism - and the mechanism that explained it in the most convincing way (including quantitative predictions of the convergence rate) - is gravitational radiation.

  22. Machel
    It is possible that in the end he will find that it is a system that oscillates between two short and long tracks.
    For this they will probably have to award another Nobel Prize.

  23. Zarathustra:
    It would have been better if you had mentioned sources.
    There are reasons for both moving closer and moving away, and what happens in the end is the result of calculations that take everything into account and the result can be moving away or moving closer.
    For example, one of the reasons for moving away is tidal forces.
    If the orbit is above the stationary orbit, the tidal forces will cause it to move away, and if it is below it, they will cause it to approach.
    The Nobel Prize was awarded because the final result that took into account both tidal forces and gravity waves was correct.

  24. deer
    Although true, recently two astrophysicists did a survey on pairs of neutron stars.
    And it turned out that there is a completely opposite phenomenon of moving away and increasing the track, the matter is still under testing. If it is approved, will it be necessary to return the Nobel? Maybe?

  25. In addition to Michael's words, it is important to emphasize two points:

    1. The evidence for the existence of gravitational waves (the approach of two neutron stars) is very reliable and a Nobel Prize was awarded long ago in this matter (no small thing).

    2. Gravitational waves have not been detected to date due to the required sensitivity of the instruments - the non-detection so far is in accordance with the theory (which predicts that with the instruments in our hands we can only detect extreme events that occur once in many years) and therefore the non-detection does not indicate the non-existence of gravitational waves. Most likely (as most of those involved in the field believe) gravitational waves will be discovered in the coming years.

  26. A. Ben Ner:
    It is true that gravitational waves have not been measured directly, but indirect evidence of their existence was received a long time ago - and precisely in the context in which they were mentioned here - namely - the decay of stellar orbits.
    You are welcome to read for example here:

    Look for the word evidence

  27. To Michael
    Along with what you wrote, it is worth noting that gravitational waves have not yet been measured and are still a prediction.

  28. Hi Hayadan:
    Please edit this article! The Hebrew is awful!
    No need to publish this response, just fix the article - it is way below your standard.

  29. Sherlock:
    So what? You still don't understand? I told you that understanding is not your territory!

  30. Mahmoud:
    There is a known mechanism that causes two neutron stars like any two stars orbiting each other to lose momentum and collapse into each other.
    This mechanism is called...
    Gravitational waves.
    Accelerated mass creates, according to the theory of relativity, gravitational waves and circular or elliptical motion is accelerated motion.

  31. There is no known mechanism that can allow two neutron stars orbiting each other to lose momentum and crash into each other. They can rotate for hundreds or thousands of billions of years without changes in orbit.
    Also, the diameter of neutron stars is so small that the chance of a random collision is zero relative to the chance of suns colliding.
    Therefore the chance of measuring gravitational waves resulting from the collision of neutron stars is zero.

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