Minor Phenomena

Do you often read astronomy articles and get confused by some terms introduced ? Here are the few Major Ones

Hydrogen Fusing

All the stars possess hydrogen in their cores which fuses to helium and provides energy(heat) which creates outward pressure which prevents star from collapsing due to its own gravity(due to mass).

Red Giant

When all of the hydrogen burns to helium and the balance of the fusion energy and gravity doesn’t remain and gravity and gravity takes the edge and starts contracting the star , then heat builds up inside the star’s core and the little hydrogen fuses to helium. This ignition of hydrogen expands the outer layer of the star and it grows bigger and takes the name of Red Giant(big enough to swallow mercury)

Red Giant

Triple Alpha process

A reaction that takes place in the core of red giant when the helium gets converted(burned) to carbon

He(4) + He(4) à Be(8) + gamma rays

Be(8) + He(4) à C(12) + gamma rays

Binary Systems

Binary symbolizes two stars/bodies. Two astronomical bodies due to their attraction of gravity start to orbit each other around the barycenter. These astronomical bodies orbit pretty close to each other.

Two stars(binary bodies) orbiting each other

Barycenter

The point where center of mass of two bodies lie.

Gravity Collapse

The contraction and collapse of an astronomical body as a result of its own gravity which is due to its immense mass . And this tends to draw all of this star’s matter towards the center of gravity of star.

Electron Degenerating pressure

In a white dwarf the electrons of atoms inside are so close that they smash each other and acquire all the energy levels and gravity can’t push the star further as the electrons are forced to go where they can’t go. So this force which opposes the gravity is called electron degeneracy pressure.

Chandrasekhar’s limit

When the force of gravity acts on white dwarf , electrons get closer and closer until they squeeze and can be squeezed no more. This degenerate matter(inside white dwarf) has quite abnormal behavior , for example the more massive the dwarf will be the more electrons will be squeezed together to handle the weight of dwarf , but there’s a limit to this squeezing of electrons i.e the increase of mass. This limit is called Chandrasekhar’s limit. This reads as the maximum mass a dwarf can have is 1.4 x (solar mass).Beyond that mass while dwarf is subject to further gravitational collapse which makes it either a neutron star or black hole.

Carbon Detonation

A white dwarf’s inside(the core) contains carbon and the dwarf isn’t hot enough to burn the carbon. If a white dwarf finds a binary companion accretion starts.

Accretion:

When a white dwarf comes in contact with a star , it starts pulling matter from the other star onto itself resulting an increase in mass.

Accretion Process

When this accretion starts the dwarf gains matter and mass becomes to humongous that the gravity takes a plus point over electron degeneracy pressure and white dwarf starts to contract and heat is produced which is enough to ignite the carbon within , and this fusion process should create enough pressure to counter balance the gravity and expand the star but unfortunately this fusion doesn’t create enough outward pressure. This blockage of expansion of dwarf and immense heat in the core increases temperature dramatically leading to thermal runaway reaction which leads to Type-2 supernova in which the outer layer of dwarf explodes and the core implodes , creating a shock wave and a lot of luminosity.

Other way of carbon detonation is when two white dwarfs bind to each other and collective mass exceeds Chandrasekhar’s limit and the fate is same as described above except in this case the explosion is called Type 1a supernova.

SN1006

An event abbreviated as “Super Nova 1006” is the brightest occurred stellar in the history. It’s brightness was 16 times the brightness of Venus and this could be seen in day time too. It was observed across China , Iraq , Egypt and Europe. This happened between April 30 , and May 1 , 1006 AD on constellation of Lupus. In  1960 first generation X-Ray satellites were sent in space and SN1006 was one of the faintest X-Ray source.

A picture taken of SN1006

Black dwarf

White dwarfs are extremely hot. The heat is trapped within the  layer and the only heat that escapes is the one on the outer layer through thermal radiation as conduction can’t take place. So it takes trillions of years for the white dwarf to cool down and when it does it turns into a black dwarf which has no energy to give and has zero luminosity , and black dwarfs may evaporate as they are a composition of protons and others.

Black Dwarf

Nova

It is an astronomical event that causes sudden appearance of a bright light which has a lot of magnitude and it fades away with time.

Roche Lobe

The region around a star in a binary system within which the orbiting material is gravitationally bound to that star. It is usually a tear drop shape , with apex of tear drop pointing to the star.(apex is L1( Lagrangian point))

Roche Lobe demonstration