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!

Neutron stars: fast spinning spheres

Can you think of something that is perhaps the size of your city but weighs more than our sun, that's what you call a neutron star!

Neutron stars are the remains of the cores of dying stars. They are formed when a star which has the mass of 6 to 20 suns explodes into a supernova. They are small in size but extremely dense. About a tablespoon of material of neutron stars would weight about one billion ton, more than the Mount Everest. 

They are also the objects with the strongest known magnetic fields, billions of times that of the Earth's.

They spin, much like a lot of objects in the space. But their pace in very fast. These rapid spins, combined with the strong magnetic fields, causes these to emit light. These are called pulsars. The pulsar, PLS J 1748-2446A spins about 43000 times every single minute. 

And for a little bit of a fun fact the signals from the neutron stars first made the astronomers believe that they were messages from aliens .

Well, that is it for this post. See you next Sunday!!!

gravitational waves

Gravitational waves are like 'ripples' in space. They are invisible and travel at the speed of light. 

But before going into their properties, let us discuss how they're formed. 

Just as I mentioned above, imagine you move your finger though a calm water body. Ripples would be formed, right? That is somewhat similar to how gravitational waves are formed.

Picture it like this. Your finger is a body in space that accelerates, and the calm water is the fabric of space time.  That is how these waves are formed. 

They are formed due to the acceleration of anything, even you and me. But the light weighed objects produce very weak waves, which cause no direct effect and cannot be detected using present technologies.

We can only detect waves that are very strong. And the strength of a gravitational wave is directly proportional to the mass of the cause. So, the greater the mass of the objects accelerating, the stronger the wave.

These strong gravitational waves include the ones formed when two black holes merge, or when there is an asymmetrical supernova formation, or neuron star collisions!

Now, let's understand the physics behind this.

When these massive objects accelerate they disrupt the fabric of space time that waves form

Now speaking of their properties, gravitational waves stretch and squeeze the fabric of space time itself as they pass, resulting the stretching and squeezing of the matter that come in the way. 

However, they do impact the matter that comes in way but they do not interact with matter, meaning they don't get blocked by it. This comes as an advantage for research because light and electromagnetic radiations get absorbed or scattered the matter coming in their way. But gravitational waves do not, meaning we can study their sources in detail.

If there is anything in particular about space that fascinates you, please share you enthusiasm in the comments down below!

The observable universe: The part we can see

Observable universe, on hearing, might sound like the amount of universe we have observed so far. But that is not what it is. So the observable universe (with a diameter of 93 billion light-years) is the region from which light has had the time to reach our Earth so far.

Let me explain. So, as we all know, our universe is about 13.8 billion years old. This means that the light from the distant object has to travel about 13.8 billion years. 

And as no object can travel faster than the speed of light. However, the universe or space is expanding faster than the speed of light. So light has to travel this obscure amount of space, and it is getting redshifted (I have discussed redshift in detail in one of my previous posts.)

Some amount of this redshifted light is significant so we can see it. But the light of the bodies far away from us is getting redshifted to the radio spectrum, which cannot be seen by us.

But don't worry as the observable is, in fact, constantly growing.

I hope you found this post helpful. 

See you next Sunday! 

Why were constellations so important so the ancients

 It is truly fascinating how all of the ancient civilisations gave significance to constellations. Then a question arises, why were constellations so important to them? They weren't scientifically developed enough to think an alien life might exist on a planet near any of these. 

So again, why? 

The First reason could be their search for a reason. Ever since its early stages, humanity has tried to find a reason for everything. Whether it be the rain, eclipses, mountains, snow, or our own existence. Constellations also come in this list. That is why they tried to find a reason as to why certain stars always exist in groups and form a certain shape. They used it in storytelling, connected it to mythology and folklore, comparing them to gods and goddesses and connecting them to legends. 

People needed something to guide them philosophically. And hence astrology came into existence. 

But this guidance was not just emotional. They also needed it to guide them through journeys as they did not have maps, and physical features like wind and weather were not reliable. 

But constellations were. They were stationary. 

Constellations appeared at different times of the year. And hence helped in determining the season, helping in determining cropping patterns.