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Re: back to 1987a

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  • peaceharris
    ... one ... that you ... is almost ... recognize a ... Nisenson ... Harris: In a previous mail, I explained that there were some astronomers which claimed
    Message 1 of 10 , Apr 1, 2003
      > Pi:
      > Right. None of the professional astronomers have identified even
      one
      > additional supernova in that patch of sky ... let alone the two
      that you
      > claim.
      >
      > Nisenson does, however, say that the "bright object" he observed
      is "almost
      > certainly a phenomenon related to the SN." However, Nisenson is a
      > professional astronomer who could reasonably be expected to
      recognize a
      > supernova if he is looking at one. Yet, it is pretty clear that
      Nisenson
      > didn't think the additional object is/was another supernova.

      Harris:
      In a previous mail, I explained that there were some astronomers
      which claimed that the 2nd source was an independent light source,
      and not a "phenomenon related to the SN".



      > Pi:
      > I'm trying to tell you that:
      > 1) Neutrino bursts are a prediction with respect to TypeII
      supernovae.
      > 2) A neutrino burst was detected before sn1987a
      > 3) If, as you have asserted, there are additional (larger)
      supernovae in
      > that area, then we should also have detected neutrino's from them.
      >

      Harris:
      A type II supernova is defined as a supernova which has hydrogen
      lines.
      I have explained to Pi that the second source was not
      showing hydrogen lines. By definition, the 2nd source was not a type
      II supernova.

      Pi claims that if there were additional supernovae, we should have
      detected neutrinos from them. This is simply not true for the simple
      reason that we have not detected neutrinos from many other supernovae
      inspite that we have better equipment today than in 1987.

      > Pi:
      > No. I'm trying to tell you that there is no solid evidence of an
      additional
      > supernova (let alone two) in the vicinity of sn1987a and at about
      the same
      > time.

      Harris:
      If you detect a type I supernova, what is the evidence that it is a
      type I supernova?

      Pi:
      In the case of sn1987a, that
      > remnant is a developing neutron star. There should be similar
      remnants for
      > your other two alleged supernovae. Once again, not one astronomer
      has
      > reported such a finding.

      Harris:
      The current theory of type II supernovae predict that neutron stars
      are formed from type II supernova. Anyone who believes the book of
      Genesis, would know that stars and the sun were created on the same
      day, implying that the sun could never have been a supernova.

      Therefore believers have to conclude that the current theory is
      wrong. Anyway, if the current theory is correct, surely Pi would
      correct me by showing me a current photo of a neutron star in the
      same position where sn1987a was.

      (Those of us who have seen the most updated photos of sn1987a know
      that only the ring is slightly visible, the central source has
      completely blacked out)

      Pi is going to give the excuse that our telescopes are not powerful
      enough to see the neutron star. Maybe he can come up with a better
      excuse.
    • David Bowman
      ... I doubt any physicist made this prediction. All supernovae are *not* supposed to have a large neutrino burst. Only the supernovae that are due to the
      Message 2 of 10 , Apr 1, 2003
        Regarding the questions that Harris has asked in his discussion with Pi:

        > ...
        >Harris:
        >Who was the physicist which made the prediction that all supernovae
        >have a neutrino burst?

        I doubt any physicist made this prediction. All supernovae are *not*
        supposed to have a large neutrino burst. Only the supernovae that are
        due to the gravitational collapse of the spent iron-rich core of
        *high mass* stars (i.e. Type II, Type Ib/c supernovae that form a
        neutron core) are supposed to have a powerful neutrino burst.
        Supernovae that occur because a white dwarf accretes sufficient mass to
        exceed the Chandrasekhar white dwarf mass limit (i.e. Type Ia
        supernovae) are *not* supposed to have much of a neutrino burst.

        If Harris knew understood the scientific explanation of how the
        various types of supernovae work, and if he knew a little particle
        physics he would know the answer to his question.

        First off every time a u-quark is transmuted into d-quark (inverse
        beta-decay) a neutrino is emitted (or an antineutrino is absorbed).
        This happens whenever a proton (uud) is transmuted into a neutron (udd).
        (In the reverse process of regular beta decay a d-quark is transmuted
        into a u-quark and is accompanied by the absorption of a neutrino or the
        emission of an antineutrino.) What happens in inverse beta decay is
        that a u-quark in the proton emits a virtual W+ (weak vector boson
        charged current) particle and in the act the u-quark is converted to a
        d-quark. The virtual W+ particle *immediately* decays into a positron
        (anti-electron) and an electron-neutrino. In typical fusion reactions
        the positron annihilates with a hapless nearby electron and the neutrino
        escapes unscathed. Meanwhile, since one of the proton's 2 u-quarks has
        become a d-quark that proton is now a neutron.

        Fusion reactions that change the number of protons by having some of
        them convert to neutrons emit an electron-neutrino for every proton
        converted. For instance the fusion reactions that convert hydrogen
        (protium) into helium emit neutrinos. But fusion reactions that
        convert deuterium into He-4 or convert He-4 to C-12 or to O-16 do
        not emit any neutrinos.

        When it comes to supernovae those that occur because of the
        gravitational collapse of a spent iron core in a massive star emit a
        huge number of neutrinos since most of the protons in all those iron
        nuclei are converted to neutrons forming the neutron star's neutron-rich
        core that much of the rest of the collapsing material bounces off of.
        The huge outbound flux of neutrinos (along with the core bounce) is
        significantly responsible for propelling the rest of the formerly
        inbound material outward as the supernova explosion in a Type-II (or
        Type Ib, or Type Ic) supernova.

        But in a Type Ia supernova a white dwarf (mostly a ball of carbon and
        oxygen about the size of the earth but with over a solar mass or so)
        accretes enough matter so that its mass exceed the Chandrasekhar limit
        of 1.4 solar masses which is the largest mass that a white dwarf can
        have and still remain stable with it being supported against gravity by
        its electron degeneracy pressure. Once this mass limit is transgressed
        the electron degeneracy pressure is no match for the inward
        gravitational forces pulling the nuclei closer together. The higher
        density and temperature caused by the gravitational squeezing action of
        the compressing carbon-oxygen mixture eventually reaches the point of
        igniting explosive carbon-carbon fusion reactions that produce mostly
        Ne-20 and Mg-24. Since both the reactants and the products have an
        equal number of protons and neutrons essentially no protons are being
        converted to neutrons and no neutrinos are emitted as a neutrino burst
        from this explosive reaction that propels the supernova.

        This doesn't mean that *no* neutrinos are emitted at all. They just are
        not emitted in the main relations that power the supernova's energetic
        release. The carbon bomb that is a Type Ia supernova is extremely
        energetic and luminous and in the outbound debris from it are produced
        a plethora of other nuclei and a whole assortment of various isotopes
        of many kinds of elements (e.g. Co56) and--many of these are
        transmutations of some other minority species of other types of nuclei
        already present in smaller amounts. Some of these secondary relations
        involve inverse beta reactions (which liberate neutrinos) and others
        involve beta-decay relations (that liberate anti-neutrinos). But the
        total flux of these neutrinos and anti-neutrinos is much smaller than
        the huge neutrino burst from a Type-II supernova that results from the
        very rapid formation of a neutron core of over a solar mass.

        > ...
        >Is Pi trying to tell me that all fusion reactions emit neutrinos?

        I think Pi specified that he was discussing Type II supernovae which
        *do* happen to emit a neutrino burst. Recall that SN1987a was a
        Type-II supernova.

        I guess I ought to mention that it is conceivable that under some
        special circumstances it *might* be possible for some protons to be
        converted to neutrons without the emission of any neutrinos, but the
        possibility of this is subject to serious doubt, it would have to violate
        the standard model of particle physics, and it has never been seen to
        date. It is conceivable that neutrinos are there own antiparticle. In
        the standard model anti-neutrinos are distinct from neutrinos, but that
        distinction has never been definitively verified by experiment. It is
        only a theoretical result from the standard model. *If* it so happens
        that neutrinos *are* their own antiparticle, and if they have a nonzero
        mass (which the recently observed oscillations seen in the flux of solar
        neutrinos indicates is the case since neutrino oscillations can only
        occur if the neutrinos have a nonzero mass) then they would be a type of
        particle called a Majorana fermion, and if they were such Majorana
        fermions then there is an allowed beta-decay mode and inverse beta-decay
        mode involving an even number of protons coherently changing into an
        even number of neutrons (or vise versa) that result in the emission of
        no neutrinos at all. This hypothetical process is called "neutrinoless
        double beta decay" but it has never yet been observed although there has
        been much experimental research aimed at looking for it. Also, even *if*
        it is possible for pairs of protons to be interconverted with pairs of
        neutrons without the emission of neutrinos, it would still be a very rare
        occurrence that requires special circumstances that would not have much
        effect on the overall flux of neutrinos coming from stars and supernovae.

        > ...
        >Harris:
        >If you detect a type I supernova, what is the evidence that it is a
        >type I supernova?

        Type I supernovae do not have hydrogen absorption lines in their
        spectra. It is thought that this is because the progenitor stars of
        type I supernovae are missing a hydrogen-rich outer envelope. In the
        special case of type Ia supernovae they are missing hydrogen in their
        spectra because their progenitor star is a white dwarf made of mostly
        carbon and oxygen. They expelled their hydrogen envelope much earlier
        as a planetary nebula when the white dwarf was being formed. Type Ic
        supernovae are thought to come from high-mass stars whose outermost
        hydrogen envelope had been previously stripped off if it (possibly due
        to interactions with a close-in compact binary companion). Type Ib
        supernovae are very similar but both their outer hydrogen envelope and
        the next helium-rich layer had been stripped away before blowing up as
        supernova.

        But type II supernovae *do* have hydrogen absorption lines in their
        spectra and it is thought that they have their outer hydrogen envelope
        more or less intact when they blow up as a supernova.

        >Pi:
        >> In the case of sn1987a, that
        >> remnant is a developing neutron star.

        Actually the neutron-rich core forms nearly instantaneously at the
        moment of the initial explosion. What takes time is for that neutron
        star core to become visible after the surrounding envelope of luminous
        remnant material thins and fades out sufficiently to uncover it.

        >> There should be similar remnants for
        >> your other two alleged supernovae. Once again, not one astronomer has
        >> reported such a finding.
        >
        >Harris:
        >The current theory of type II supernovae predict that neutron stars
        >are formed from type II supernova. Anyone who believes the book of
        >Genesis, would know that stars and the sun were created on the same
        >day, implying that the sun could never have been a supernova.

        Anyone who knows the rudiments of astrophysics knows that the sun
        was never a supernova anyway. But it is likely that the sun formed
        from the gravitational collapse of a region of the interstellar medium
        that had been enriched by the material that came from a relatively
        nearby type II supernova, and the shock wave that so enriched it
        probably triggered the collapse itself.

        >Therefore believers have to conclude that the current theory is
        >wrong. Anyway, if the current theory is correct, surely Pi would
        >correct me by showing me a current photo of a neutron star in the
        >same position where sn1987a was.

        Give it time to become uncovered. BTW neutron stars tend to be
        mostly invisible in visible light at large distances because they
        are only about 10 km in radius or so and even a very bright surface
        results in a tiny luminosity in visible light. Neutron stars tend
        to have their presence betrayed by powerful radio pulsar emissions
        resulting from an interaction of the trapped rotating magnetic field of
        the neutron star with a plasma of matter surrounding it, or from
        various x-ray emission phenomena that are energetic enough to be seen
        in spite of their tiny surface area.

        >(Those of us who have seen the most updated photos of sn1987a know
        >that only the ring is slightly visible, the central source has
        >completely blacked out)
        >
        >Pi is going to give the excuse that our telescopes are not powerful
        >enough to see the neutron star. Maybe he can come up with a better
        >excuse.

        What's needed is to wait for the debris around the neutron star core
        to thin to the point that it is uncovered enough to make its presence
        known.

        Dave Bowman
      • peaceharris
        ... *not* ... Harris: The reason why I asked that question was because Pi asked me whether another neutrino burst was observed in march 1987. Bowman: Only the
        Message 3 of 10 , Apr 1, 2003
          --- In OriginsTalk@yahoogroups.com, "David Bowman"
          <David_Bowman@g...> wrote:
          > I doubt any physicist made this prediction. All supernovae are
          *not*
          > supposed to have a large neutrino burst.

          Harris:
          The reason why I asked that question was because Pi asked me whether
          another neutrino burst was observed in march 1987.

          Bowman:
          Only the supernovae that are
          > due to the gravitational collapse of the spent iron-rich core of
          > *high mass* stars (i.e. Type II, Type Ib/c supernovae that form a
          > neutron core) are supposed to have a powerful neutrino burst.
          > Supernovae that occur because a white dwarf accretes sufficient
          mass to
          > exceed the Chandrasekhar white dwarf mass limit (i.e. Type Ia
          > supernovae) are *not* supposed to have much of a neutrino burst.
          >
          > If Harris knew understood the scientific explanation of how the
          > various types of supernovae work, and if he knew a little particle
          > physics he would know the answer to his question.

          Harris:
          I don't know the scientific explanation for various types of
          supernovae. All I know that if a supernova consists of predominantly
          1H, then any fusion reaction to form heavier elements must be
          accompanied by neutrino emission, since the reaction of protons to
          form a new neutron is accompanied by neutrino emission.

          As far as other fusion reactions are concerned, neutrino emission may
          be possible but not a neccessity.


          Bowman:
          > Anyone who knows the rudiments of astrophysics knows that the sun
          > was never a supernova anyway. But it is likely that the sun formed
          > from the gravitational collapse of a region of the interstellar
          medium
          > that had been enriched by the material that came from a relatively
          > nearby type II supernova, and the shock wave that so enriched it
          > probably triggered the collapse itself.
          >
          >
          > Give it time to become uncovered. BTW neutron stars tend to be
          > mostly invisible in visible light at large distances because they
          > are only about 10 km in radius or so and even a very bright surface
          > results in a tiny luminosity in visible light. Neutron stars tend
          > to have their presence betrayed by powerful radio pulsar emissions
          > resulting from an interaction of the trapped rotating magnetic
          field of
          > the neutron star with a plasma of matter surrounding it, or from
          > various x-ray emission phenomena that are energetic enough to be
          seen
          > in spite of their tiny surface area.

          Harris:
          Thank you for correcting me. I was wrongly under the impression that
          neutron stars are defined as those stars which produce and emit
          neutrons (as its name suggests). After checking my textbooks, I
          realized that the definition of a neutron star is as you say.

          Bowman:

          >
          > What's needed is to wait for the debris around the neutron star core
          > to thin to the point that it is uncovered enough to make its
          presence
          > known.

          Harris:
          If this happens during my lifetime, I will conclude that the
          physicist who made this prediction was a mighty genius.
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