The Life And Times Of An Average Star

If you’re anything like me; you would find this picture absolutely beautiful. It contains a unique, sort of universal beauty. Something that can be adequately appreciated by almost anyone. The most amazing thing is that this is real; nature at it’s finest. The bright, wispy cloud of coppery white unattached, hovering over the vast enveloping darkness of space. At the right you can see an ethereal blob of green; merely a few inches on your screen but in reality a couple of light-years across.

File:VST image of the star-forming region Messier 17.jpg

Just your average portrait of the Universe

But perhaps even more awe-inspiring is the sheer immensity of it. The specks of light you see riddled across your screen are stars. Stars just as massive and radiant as our own sun. This cascade of colour and light you see on your screen is a nebula. A stellar nursery. The maternity ward of the stars. Across the universe, it is in places like these that gas and dust coalesces and fabricate stars such as our sun.

File:ESO-The Omega Nebula-phot-25a-09-fullres.jpg

Still the Omega Nebula

Considered one of the brightest and most massive star-forming regions of our galaxy; this particular little beauty is called the Omega Nebula. Discovered by Philippe Loys de Chéseaux in 1745.  It is located in the rich starfields of the Sagittarius area of the Milky Way; around 5,000 to 6,000 light-years from Earth. Just to fully fathom what 6,000 light years could mean, imagine taking a trip from London to New York and back 5,089,610,231 times. That’s FIVE BILLION, EIGHTY-NINE MILLION, SIX HUNDRED AND TEN THOUSAND AND TWO HUNDRED AND THIRTY ONE times. If you travel to the Omega Nebula from an average, everyday airliner (assuming you can store enough fuel aboard your plane) ; it would take you 71,254,543,220 hours to get there. So you would be around 8,134,080 years old by the time you reach it if you had begun the journey since birth. In other words you would die long before you ever saw the nebula. The nebula itself spans some 15 light-years in diameter (I’ll let you imagine for yourself how enormous that must be) and the total mass of the Omega Nebula is an estimated 800 solar masses-  800 times the mass of our sun.

However, it doesn’t just stop there. As I’ve said before, each speck of light you see in the picture is essentially a sun. Nebulas such as these-and especially the Omega Nebula- are amongst the most densely populated in terms of stars. To get a sense of how big your average star is, have a look at this image:

The Sun is bigger than you think

The Earth -our home- is barely distinguishable as a small black dot in juxtaposition with the mighty sun. In actuality, the sun is 93 millions miles away from Earth . Despite this, it still has the power to illuminate and heat up the surface of our planet, a testimony to the fact that the sun is certainly one of the most powerful things that we know of. If you could stack Earth upon Earth inside, you would be able to fit in around a million of them. The Omega Nebula itself has hundreds of stars, all of which emphasize the scale of what we’re looking at here.

Nevertheless, before we get lost in the seemingly never-ending extent of this one nebula; let’s find out how exactly it works.

Nebulae are often star-forming regions, such as in the Eagle Nebula. This nebula is depicted in one of NASA’s most famous images, the “Pillars of Creation“. In these regions the formations of gas, dust, and other materials “clump” together to form larger masses, which attract further matter, and eventually will become massive enough to form stars. The remaining materials are then believed to form planets, and other planetary system objects.

Hubble telescope image known as Pillars of Cre...

Hubble telescope image known as Pillars of Creation, where stars are forming in the Eagle Nebula. (Photo credit: Wikipedia)

However, stars aren’t just there to look beautiful above in the heavens. Most of us don’t realise just how important stars are to our existence. Firstly, consider this quote:

“If you wish to make an apple pie from scratch, you must first invent the universe.”

-Carl Sagan

Certainly quite vague and mystifying, although, keep in mind that this is one of Carl Sagan’s most famous quotes. He wasn’t exactly a poet but this single quote contains a very deep meaning, something that essentially defines what it means to be a human. He meant that all the elements that make up everything on Earth (including his beloved apple pie) come from the heart of stars riddled within the universe. This is suitably accompanied with this quote:

“The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff.”

-Carl Sagan

Quite eloquently, Carl Sagan was simply expounding on the fact that stars are the nuclear powerhouses that build up the objects you see around you. The stars are essentially factories that produce all the elements that compose you and everything else (Including the apple pie). This process of creating elements has been carried out by stars since the very beginning of the universe. So how exactly do stars do this?

To find out, let’s just back up a little bit, by a little bit I mean around 13.5 Billion years back.

Rewind 13.5 billion years and you’re in a Universe much more uniform and bleak. The Universe of yonder wasn’t as dynamic or even as large as we can witness it now. Back then, there was only one element- not the 92 naturally occurring ones we’ve found up till today. The universe was abundant with hydrogen gas; the simplest element that we know of. Gravity began to coalesce this hydrogen gas together, forming vast clouds of hydrogen. It’s important to note that despite being an extremely simple element; hydrogen is immensely powerful. As a species, we’ve been able to envisage how we can use hydrogen’s immense source of energy. This research came into fruition during the years of 1942 and 1946- The Manhattan Project helped the military to utilise the potential of hydrogen for their own purposes. Hence forming the creation of perhaps the most destructive thing that we’ve ever created: The thermonuclear bomb.

Anyway, before we get carried away with politics and the so-called ‘Tsar Bomba‘ (you have to admit, awesome name). Let’s get back to hydrogen’s immense source of power, and how this helped create the Universe that we know of today.

The immense gravitational forces that acted upon hydrogen eventually heated it up to around 10 million degrees its ‘sweet spot’ if you like. At this temperature, hydrogen begins to emit the energy that makes the stars shine. This ‘sweet-spot’ ultimately supplies the Universe with warmth and light. So, without this ‘sweet-spot’ the sun wouldn’t have formed and it wouldn’t have provided life on planet Earth with warmth and energy. Put simply: without this ‘sweet-spot’, we would never have existed.

So how does hydrogen’s energy emitting capabilities work?

It all starts with a process called nuclear fusion.

1) Gravity begins to coalesce and squish hydrogen gas together, condensing it into a single small point. Imagine a sports field full of hydrogen gas all getting squeezed down into a smaller and smaller space.

2) As the hydrogen compacts, the atoms of the hydrogen gas start bumping into each other. Saint Mary’s University in Nova Scotia, Canada demonstrate this with a bunch of small balls.

3) As the atoms vigorously smash into each other the temperature begins to rise. When the temperature reaches the critical 10 million degrees; the space the hydrogen gas occupies is about the size of a soccer ball.

4) The ’10 million’ sweet-spot is when the temperature and pressure between the atoms of the hydrogen gas is so great that the atoms actually begin to fuse together. Thus forming a new, overall heavier material called helium.

5) It turns out that it takes four hydrogen nuclei to form one helium atom, and it was known that a helium atom was less massive than all the four hydrogen nuclei on their own. It was a scientist called Arthur Eddington who first proposed that the sun shines because the hydrogen nuclei ( or atoms) fuse together to make helium, releasing the missing mass as energy.

English: English astrophysicist Sir Arthur Sta...

English astrophysicist Sir Arthur Stanley Eddington (1882–1944) (Photo credit: Wikipedia)

Arthur Eddington certainly made one of the most important discoveries in science. He had essentially found out where everything in the universe comes from, and how it continues to come about. Although, with all due respect to the guy, he was just building on a discovery made earlier In 1905.

This discovery is definitely one of the most important and profound finding in science. Also, the equation that comes with it is probably the most famous:

Urban education

This equation has grown to become one of the most famous in science. (Photo credit: wokka)

There are plenty of reasons why E=MC2 has been given so much significance and importance, amongst other things it reveals the key to the energy source of stars like our sun. The letters in the formula stand for:

Energy= Mass x Speed of light squared.

The speed of light squared is the speed of light multiplied by itself, which is a tremendous number; containing 16 noughts.

C^2 = 90000000000000000

Einstein’s equation revealed an incredible facet of nature, showing that an object with an incredibly minuscule amount of mass contains within it a tremendous expanse of energy. Consider a piece of paper money:

A British ten pound note with a picture of Darwin (Nice touch huh?)

If you hold a £10 note in your hand, you’ll find it’s feather-light. Nevertheless, woven into a bank-note is enough energy given off from a nuclear bomb. So drop the weapon, before somebody gets hurt.

What Einstein found was that ‘matter’-things you can feel and touch- is just an incredibly condensed form of energy. This links back to what Eddington meant when the missing mass given off when the four hydrogen nuclei fuse into hydrogen is released as energy. Energy and mass are two sides of the same coin. In fact, the sun alone loses 4 million tonnes of mass every second.

Right. So we’ve found out how stars form and where they get their energy. But what about Carl Sagan? What did he mean when he said “We are made of starstuff” ?. To answer this question, you have to go back to the same process that converts hydrogen into helium; nuclear fusion, and ultimately to the death of a star.

The universe isn’t just made up of hydrogen and helium, you need a bigger variety of ingredients; you require carbon, iron, nitrogen, oxygen etc. You simply can’t build a world like ours without them. The process that makes helium from hydrogen just so happens to make up the heavier elements that we associate with. Once the hydrogen has converted into helium, the helium sinks down into the core of the star. This happens because the helium is slightly more dense, hence causing the lighter hydrogen to rise above. As the helium atoms fuse together, they again form a slightly heavier element; carbon. Already, a star has produced something that is vital to every living thing; organic compounds contain carbon, and organic compounds are what life is made of. Carbon is part of all life as we know it. The missing mass again is released in massive expanses of energy. This process continues to carry on; with the new, heavier element that’s formed sinking down into the centre of the sun. This eventually causes the star to because layered, causing a sort of ‘Russian Doll’ of elements.

Throughout it’s life; a star becomes layered like an onion.

If you go deeper down towards the centre of the star, you’ll find that the elements become increasingly dense. Here, you would find elements like neon and oxygen; something that is essential for our respiration process. This happens until you hit Iron, which is when things start to change. Iron doesn’t produce energy when it fuses, so the star is now unable to sustain itself. More and more Iron starts developing in the star’s core before nearly all the remaining fuel runs out. I stress the word nearly because then, the atoms of the element next heaviest to iron would be completely dedicated to fusing into iron, therefore, there wouldn’t be any of the element left.

As the star cannot sustain itself, gravity: the great sculptor of the universe, takes over. It begins to squash the star in on itself, compressing the core to immense pressures. The temperature then begins to soar to phenomenal levels. Finally the star collapses and explodes, bursting out its ‘enriched guts’ into the space beyond. This is called a ‘supernova’. 

A Supernova is the death of a star, and what a spectacular death it is!

The elements bundled within the star are now released out, free to form whatever they might in the universe.

However, it doesn’t just end there, in the brief microseconds where the elements are blasted out, something new gets born. When the star explodes, a massive shock wave passes through it and the blast is so powerful that it forces some of the iron to fuse together to form even heavier elements. And that’s how heavy elements such as gold or platinum or lead are made. They are forged in the heart of an exploding star. Sometimes, the supernova of a star may contribute to the formation of a new star, nonetheless, it’s countless supernovas such as these that have ultimately forged the elements on Earth. As well as the heavy elements in the rest of the universe.

The gold adorning your body has a violent past.

In fact, everything in our world has a violent past. We are all fundamentally children of the stars, born out of the chaotic explosion at it’s death. Stephen Hawking puts it best:

“It never seizes to amaze me that our bodies are constructed of the stuff of stars”

– Stephen Hawking

In many ways, knowing this places much more beauty and elegance into the already dazzling allure of the stars. In the beginning I’ve talked about how the beauty of the stars and the nebulae is a sort of beauty that can be appreciated by anyone. Now, we realise that the stars are even more radiant and magnificent than we ever could’ve imagined.

That, Is the nature of science.

Other awesome stuff:

Just a badass image.

‘They May Be Giants’, a band that sings about science. What more could you possibly want?

Stephen Hawking:

 

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One thought on “The Life And Times Of An Average Star

  1. Pingback: Lyrical Essay (Part 2): “Escapism” « Arza Winters

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