Gravitational Wave Observations

Type-II Supernova and the role of neutrinos

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Neutrino, Supernovae

Mains level : NA

This newscard is an excerpt from the original article published in The Hindu.

Another space-based abstract terminology has appeared in TH.

What is the news about?

  • Many stars, towards the end of their lifetimes, form supernovas – massive explosions that send their outer layers shooting into the surrounding space.
  • Most of the energy of the supernova is carried away by neutrinos – tiny particles with no charge and which interact weakly with matter.
  • Researching the mechanisms of the so-called Type II supernovas, a team from IIT Guwahati has come up with new insights into the part played by neutrinos in this dramatic death of massive stars.

What are Neutrinos?

  • Proton, neutron, and electron are tiny particles that makeup atoms.
  • The neutrino is also a tiny elementary particle, but it is not part of the atom.
  • Neutrino has a very tiny mass, no charge and spins half.
  • It interacts very weakly with other matter particles.
  • Neutrinos come from the sun (solar neutrinos) and other stars, cosmic rays that come from beyond the solar system, and from the Big Bang from which our Universe originated.
  • They can also be produced in the lab.

Their types

  • Neutrinos come in three ‘flavours’, another name for ‘types’, and each flavour is associated with a light elementary particle.
  • For instance, the electron-neutrino is associated with the electron; the muon-neutrino with the muon and the tau-neutrino with the tau particle.

What is Supernova?

  • All the stars burn nuclear fuel in their cores to produce energy.
  • The heat generates internal pressure which pushes outwards and prevents the star from collapsing inward due to the action of gravity on its own mass.
  • But when the star ages and runs out of fuel to burn, it starts to cool inside.
  • This causes a lowering of its internal pressure and therefore the force of gravity wins; the star starts to collapse inwards.
  • This builds up shock waves because it happens very suddenly, and the shock wave sends the outer material of the star flying. This is what is perceived as a supernova. This happens in very massive stars.

Try this PYQ:

Q. Which of the following is/are cited by the scientists as evidence/evidence for the continued expansion of the universe?

  1. Detection of microwaves in space
  2. Observation of redshirt phenomenon in space
  3. Movement of asteroids in space
  4. Occurrence of supernova explosions in space code

(a) 1 and 2 only

(b) 2 only

(c) 1, 3 and 4

(d) None of the above can be cited as evidence

The Type-II Supernova

  • In stars that are more than eight times as massive as the Sun, the supernova is accompanied by a collapsing of the inner material of the dying star – this is also known as core-collapse supernova or Type II supernova.

Role of neutrinos

  • The collapsing core may form a black hole or a neutron star, according to its mass.
  • As they spew out of the raging supernova, the neutrinos can change from one flavour to another in a process known as neutrino oscillations.
  • Due to the high density and energy of the supernova, it generates neutrino oscillations happening simultaneously over different energies (unlike normal neutrino oscillation), termed collective neutrino oscillation.
  • The oscillation result may dramatically change when one allows the evolution with the angular asymmetry, the oscillations can happen at a nanosecond time scale, termed fast oscillation.
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