Antimatter

In this post, we will be understanding something quite fascinating- antimatter. 

Basically, it is the mirror image of matter. As you must know that in the nucleus of the atom, lie neutrons, which have a neutral charge and protons which have a positive charge. In the orbits around the nucleus lie electrons, which have a negative charge. Electrons and protons are equal in number, neutralizing the effect of each other.

But in antimatter, it is the complete opposite. In the nucleus lie antiprotons which have a negative charge and in the orbits lie the positrons (anti electrons) which have a positive charge. 

When antimatter and matter come in contact with each other, they both annihilate each other, leaving nothing but energy. It is believed that during the Big Bang, equal amounts of matter. But then a question arises. If equal amounts of matter and antimatter were created, they must have annihilated each other, and had left energy behind. But then why do we have all of this matter around us, while antimatter isn't so common.

Why has matter (Baryons) dominated antimatter?

This is what we call the Baryon asymmetry. We do not yet have any solid explanation behind this, but we do have some theories that might be some help. 

The most widely accepted theory is that of baryogenesis. This is a hypothetical phenomenon, according to which a tiny amount of surplus matter was created. so when matter and antimatter did annihilate, this tiny around survived and that is what everything we see around us is constituted of.

I hope you found this helpful. 

If you have any suggestions feel free to drop them down. 

See you next Sunday!

Dwarf Galaxies: to small to be galaxies

Dwarf galaxies are simply galaxies relatively smaller in size and containing just a few hundred of thousand or just a few few billions of stars. This sounds like a lot, but when compared with larger galaxies such as ours (between 100 to 400 billion stars), the number appears somewhat smaller.

Being small and containing lesser stars, they have low mass. Due to the lack of abundance of stars, they have low luminosity too. They are very common actually. 

In fact loads of them also orbit other galaxies. take ours for example. The Milky Way has at the very least, about 14 galaxies orbiting it. 

Formation: Dwarf galaxies can be formed due to the collision between galaxies, which ejects streams of materials and dark matter, which cluster together to form smaller dwarf galaxies.

Another possibility can be that they were formed during the early stages the creation of the larger galaxies.

Types: Dwarf galaxies can be broadly categorized into five categories. Three of them are the same as the that of the 'regular' galaxies. But the last two get interesting.

Irregular dwarf galaxies:- They are irregular in their shape, just as the name sounds.

Elliptical dwarf galaxy:- They are ellipsoidal in shape, and smooth and featureless in appearance. 

Spiral dwarf galaxy:- Again, as the name suggests, they are spiral in shape (similar to the Milky Way)

Blue Compact Dwarf:- They contain massive hot stars (the blue ones are the hottest). These hot ones make the star look blue in colour.

Ultra Faint Galaxies:- They have the least number of stars, making them look faint. They also have large amounts of dark matter.

Examples: 

• Leo A: Irregular Dwarf galaxy
• Small Magellanic Cloud 2: Irregular Dwarf and a satellite of the milky way

Binary stars

When observed for a long time, some stars seem to change the amount of light emitting. It can be caused due to two reason. Either they are a variable star (which I will discuss in a separate post) or they are in a binary system and one star had eclipsed the other. 

In order to understand the massive paragraph above, you will have to understand the term 'binary stars."

BINARY STARS

Binary stars are a system of two stars which are gravitationally bound to each orbit a common centre (called the barycentre). 

These two stars can differ in shape, size, masses and stability. The larger star is called the primary star and the smaller star is called the secondary or the companion star.

The eclipses of these stars are very much important to us. These can help us in determining their size, shape, masses, diameters, and sometimes their orbits too.

Binary stars might seem uncommon but about 85% of the total stars exist in binary systems.

THE DEMON AND THE DOPPLER EFFECT

With some binary stars, we are lucky enough to discover their orbits simply by looking at them, but that is really not the case very often. For instance Algol (meaning demon in Arabic). 

In this binary stars system, the two stars are so close, that it is almost impossible to distinguish them as individuals, even through a telescope.

In such cases, the Doppler effect comes into help. The Doppler effect help in determining their individual orbits as they move farther from us and the colour of the light coming from them changes too.

ALLIANCE

If the two stars are very close, then one star's tidal effect can affect the other's shape and size, and hence influencing it's lifespan. These stars can sometimes collide to form elements like gold and platinum.

MULTIPLE STAR SYSTEM

just like two star system, multiple star systems also exist, though these are somewhat uncommon to find.

That is it for this post.

See you next Sunday!