On 10 m=E4rts, 01:06, Tim Little <t...@[EMAIL PROTECTED]
>
wrote:
> On 2008-03-09, Crown-Horned Snorkack <chornedsnork...@[EMAIL PROTECTED]
> wrote:
>
> > When a neutron star fills and spills over its Roche lobe, some of the
> > escaping matter falls towards the other neutron star or black hole,
> > but some escapes outwards. But the part which escapes on the outer
> > side is not at infinity! It is bound, on a circular orbit, pretty deep
> > in the gravity well of the (old or new) black hole.
>
> Yes, some will. As I recall we were originally talking about matter
> that did actually escape, though. Certainly the accretion disk will
> have some strange nuclear species in it.
>
> > IIRC, tritium releases 18 keV per decay - half of which goes away with
> > neutrino.
>
> The neutrino doesn't go away - the thought experiment was an isolated
> system. If there's unobtainium strong enough to contain degenerate
> neutron matter I'm sure it would have to contain neutrinos too.
>
Surely not.
There is a very real obtainium strong enough to contain degenerate
neutron matter indefinitely.
The gravity field of an ordinary neutron star.
It does contain neutrinos - briefly. The neutrinos from a supernova
diffuse and leak away over the time period of a few tens of seconds.
If a neutron star is significantly expanded then it becomes far more
transparent for neutrinos. So the neutrinos will escape in a few
seconds or less.
A really hot rarefied neutron star matter is liable to emit through
Urca process. Of course, as the disc expands, it becomes transparent
to gamma and r=F6ntgen radiation as well...
> I did get the energy of tritium decay wrong, though. The final
> conclusion still stands - the energy of tritium decay is amply enough
> to trigger a state in which nuclear interactions are common and in
> which tritium will not make up much of the equilibrium mix.
>
> > It takes a lot of energy to induce fission of lead 208. Even thorium
> > 232 is pretty resistant to induced fission!
>
> It has to be more than merely "pretty resistant" in a dense soup of
> nuclei and other particles with energies in the MeV range. The
> question is not how long they will last (which will be very short
> indeed for any particular nucleus), but how commonly they will form.
>
But my point is, how long will the nuclear energy be in MeV range,
seeing that energy can be expended through expansion and through Urca
process?
> Which nuclei will fuse to form lead-208, and how frequently compared
> with other nuclei?
>
Lead 208 and bismuth 209 are at the terminus of s-process. So,
neutrons.
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