SUPERNOVA and NEUTRINO

Subject : Science & tech

Context : A team from IIT Guwahati has come up with new insights into the part played by neutrinos in this dramatic death of massive stars.

Concept:

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.

Supernova

All 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.
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.
The collapsing core may form a black hole or a neutron star, according as its mass.

Neutrinos

Proton, neutron, and electron are tiny particles that make up atoms
The neutrino is also a tiny elementary particle, but it is not part of the atom
They are the second most widely occurring particle in the universe, only second to photons, the particle which makes up light
Neutrino has a very tiny mass, no charge and spin half
It interacts very weakly with other matter particles

Origin of neutrino

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

Types of neutrino

Neutrinos come in three types or “flavors” – electron neutrino, tau neutrino and muon neutrino
They can change from one flavor to another as they travel.
This process is called neutrino oscillation and is an unusual quantum phenomenon

How are atmospheric neutrinos produced in nature?

Atmospheric neutrinos are produced from cosmic rays which consist of protons and heavy nuclei.
These collide with atmospheric molecules such as Nitrogen to give off pions and muons which further decay to produce neutrinos.