When a giant star dies in a supernova explosion
a stellar core is left. If the stellar core
has a mass ranging from 1.4 to 3 solar mass,
it collapses, as gravity is so strong that
electrons and protons combine to form neutrons
giving birth to a neutron star. It does not
collapse further because of Neutron degeneracy
pressure.
A neutron star is one of the densest objects
in space. Just imagine compressing sun to
the size of Manhatten that is around 20 km.
If you takeout a sugar cube amount of neutron
star it will weigh about 3 billion tons.
As the name suggests neutron stars are composed
almost entirely of neutrons. Its immense gravitational
field which is 200 billion times that of the
earth, combines electrons and protons to form
neutrons. Neutron stars are very hot having
a surface temperature of around 600 thousand
K. Its magnetic field ranges from 100 million
to 1 quadrillion times stronger than the field
of the Earth.
When stellar core collapse it starts spinning
faster due to the conservation of angular
momentum. In day to day life, we can see its
effect on ice skating. When an ice skater
moves its arm and legs inward, the moment
of inertia decreases and since the conservation
of angular momentum is constant, the angular
velocity increases, resulting in the faster
spin of the skater. Due to this very reason
Neutron stars spins very fast and can exceed
100 times per second.
Because of fast rotation speed, some neutron
stars become highly magnetized and emits a
beam of electromagnetic radiation from its
poles. These neutron stars are termed as Pulsars.
When its beam of emission is pointed towards
the earth we can observe its radiation.
A Millisecond pulsar is a fast rotating neutron
star with a rotational period of 1–10 milliseconds.
Its rotation speed is triggered by accretion
of matter which is siphoned from a companion
star. It can devour the whole star material
by its extreme gravitational force. The fastest
spinning neutron star discovered rotates 716
times per second.
A Magnetar is a type of neutron star believed
to have an extremely powerful magnetic field.
Its magnetic field is quadrillion of times
more powerful than the field surrounding Earth.
When the magnetic field decay it triggers
the emission of X-rays and gamma rays. The
first recorded burst of gamma rays thought
to have been from a magnetar had been detected
on March 5, 1979
PSR J1745-2900 is a magnetar, orbiting the
supermassive black hole Sagittarius A* at
the center of our milky way galaxy.
When two neutron stars or a neutron star and
a black hole merge into each other, a spectacular
transient astronomical event occurs known
as Kilonova.
On October 16, 2017, the LIGO and Virgo alliance
announced the first simultaneous detections
of gravitational waves and electromagnetic
radiation. After analyzing the data they found
out that source was a kilonova, caused by
a binary neutron star merger. The event occurred
130 million light-years away from the Earth
in the galaxy, NGC 4993.
From the observation of Kilonova remnant,
scientists unravel the mystery behind the
occurrence of the heaviest elements in the
Universe. A neutron star merger can create
heavier elements like gold, platinum up to
uranium. Before this discovery, heavier elements
were thought to be manufactured somehow in
a supernova. A Kilonova event can create more
than 50,000,000,000,000,000,000,000,000 (Septillion)
kg of gold.
I think that’s enough for today. I will
see you in the next video. Smash the like
button and don’t forget to subscribe for
more informative videos. Thanks for watching!
