Journey to the Centre of a Neutron Star (Lecture - 11) by Professor G Srinivasan

Summer course 2018 - A Random walk in astro-physics
Lecture - 11 : Journey to the Centre of a Neutron Star
by Professor G Srinivasan, Raman Research Institute (Retired)
10.00 to 12.00 Friday, 18 May 2018
Madhava Lecture Hall, ICTS Bangalore
The range of densities, temperatures, magnetic fields, etc. that obtain in the Universe are staggering: from 10-27 g cm-3 to 1015 g cm-3, from 3K to 1010 K, from 10-6 G to 1015 G. Not surprisingly, the variety of physical phenomena one encounters during the study of celestial objects is truly impressive. This set of lectures is intended to illustrate the richness of Astrophysics. It will be a random walk in basic physics, with numerous illustrations from astronomy. The topics in physics that will be reviewed have been chosen on the basis of their importance in contemporary astronomy.
Topics:
Absorption and emission of radiation
Radiation from relativistic electrons
Compton scattering of radiation
Spontaneous and stimulated emission
Hyperfine splitting of energy levels
Molecular spectra
Astrophysical plasma.
Quantum tunnelling.
Nuclear matter
Neutrino Oscillation
Phase transitions and the early Universe
During this random walk in physics, one will encounter a range of astronomical objects and phenomena, such as, Solar wind, gaseous nebulae, interstellar hydrogen clouds, giant molecular clouds, neutron stars and pulsars, supernova remnants, radio galaxies and quasars, active galactic nuclei, the cosmic microwave background, etc.
www.icts.res.in/summercourse2018
Table of Contents (powered by videoken.com)
0:00:00 Summer course 2018 - A Random walk in astro-physics
0:00:10 Journey to the Center of a Neutron Star (Lecture - 11)
0:01:50 How does Nature make Neutron Stars?
0:08:04 Onion skin model of a star
0:12:17 Core collapse -Neutron star -Supernova
0:12:51 Neutron Star as "ground state of matter"
0:18:28 Absolute ground state of matter at zero pressure
0:26:05 A journey to the centre
0:34:56 Beta Equilibrium in the fluid core
0:38:34 Equation of state above the "neutron drip"
0:53:44 Exotic states near the centre?
0:54:40 Exotic states?
0:58:07 Bose - Einstein Statistics
0:58:35 Bose-Einstein Distribution & Fermi-Dirac Distribution
0:59:41 Bose-Einstein Condensation
1:00:45 Degenerate Bose Gas
1:04:55 Pion condensation
1:09:17 Quark - Gluon soup?!
1:14:12 Superfluidity in Neutron Stars
1:14:53 BCS Theory of Superconductivity
1:18:21 Order Parameter
1:19:23 Why superconductivity is a low temperature phenomenon?
1:21:13 Superconductors are diamagnets
1:21:48 Superfluidity and Superconductivity
1:24:38 Superfluid states in Neutron Stars
1:31:21 Superfluid in a rotating vessel
1:41:52 Neutron superfluidity
1:45:15 Proton Superconductivity
1:47:43 Type II Superconductors
1:49:34 Type II Superconductivity
1:52:25 Abrikosov vortex lattices
1:53:27 Proton superconductivity in neutron stars
1:53:32 Proton Superconductivity
1:54:26 The inter-pinning of the fluxoids and vortices
1:54:34 Coupled 'Super states'
1:57:02 Next Lecture: Millisecond Pulsars
1:57:10 Q&A

[@scenFor109]

Properties that turn metal in to superconductors 1:28:00

[@uscdave1124]

The "random walk" pun made me smile

[@mbusbridge1]

Okay. Dumb guy here... I tried to work out how far down you would have to go before the pressure was comparable to that at the centre of the earth. I came up with 7 millimeters! That way off right? I took a colum 6371km high and multiplied it by 5.51 (avg density of the earth) to get 35 billion kg roughly. Then used the billion kg per tablespoon or 5ml. 5 billion kg/ 5cm³ into 35 billion kg gave me 7mm down! Where did I screw up?

[@abhinavswami3584]

Gem

[@santyclause8034]

Why would the neutron star surface be 'solid' if its mass is so dense that it cannot form a regular crystalline molecular lattice. Would a liquid crystal be possible? Can a liquid be so densely constrained that it is to all intents a 'solid' by ordinary standards of mechanical rigidity?

[@mbusbridge1]

My guess (and it's only a guess) Would be that the solid part of the crust would be very thin, like on the order of centimeters or inches. Very thin. I think at those densities, the atoms are far enough apart that they can act like a proper crystal. It's the physical ordering of the atoms that makes them behave as such. Electrons just swim about amongst and in-between. Go down just a bit and things get weird and start behaving like liquids because of quantum effects, they get too close together and have to do a diffrent dance to follow the rules I guess. But yeah, I imagine that the iron/nickel crust is unlike anything that we have seen up close in a lab. Frozen beyond frozen, yet tens of millions of degrees K. These things boggle the mind more than black holes I say.

[@amedeofilippi6336]

I. Wonder why nobody takes into duly account the constant angular momentum of a collapsing star that could fiercely oppose to becoming a neutron star because of increasing centrifugal force.

[@santyclause8034]

Depends on the core mass not -radial velocity- Angular Momentum, still not a terrible postulate. The weight of a mass over the center of a stellar fusion body is an instantaneous moment of force, as long as the fusion mass has a critical volume density anywhere above center point, whereas radial force increases with circumferential velocity and has a gradient (rate of change) such that a distributed interval of difference is too wide to effectively balance -accelerating- rising pressure toward core singularity. Its just a guess.

[@cymoonrbacpro9426]

Remarkable a whole lecture and something that is totally hypothetical!

[@deepcoolclear]

Cymoon RBACpro it’s not hypothetical. Neutron stars exist.

[@gsyamsri8122]

My guess is YOU have something totally hypothetical in mind that you want to believe so you need to criticize anything reasonable that contraries your idea....