Download Amanda Boyle Starstuff

Amanda Boyle
Starstuff
"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
13.82 billion years ago the universe was formed. How the universe came into being is still up
for debate. Well, most of it is pretty well established: Big Bang, Expansion ad nauseum, eventual
decimation by black holes. But it's the more intimate "why"s and "so what"s and the more technical
things that are being fussed over. But that is the nature of science. It is flexible, ever changing, and
even the tiniest details are reasonable paths of study. Because in the quest of understanding it all,
nothing is too small. Nowadays, the community at large is pretty open to new ideas, theories, and
concepts so long as you back up your research with data, facts, and observations. There is no fear of
retribution or trying to fit your science into someone's framework: No inquisition, no hegemonic
dictator to answer to. In the past 100 years we have made borderline miraculous advancements,
from using mercury as 'medicine' to begin able to grow synthetic organs. However this is not the
most spectacular of all. We have learned about stars, and it is out of them, that we have been born.
If you take a moment to think about it, we should know absolutely nothing about stars.
Physically the farthest we can go is our moon, and just now are we gathering data about the edge of
our solar system. Heck, we didn't even know that Pluto, the poor little planet or not planet, had a
moon until 50 years after we found it. Then in 2005 we realized, oh wait, there are actually an
additional two more moons. We spotted another moon in 2011, and found the 5th in 2012 while
charting the trajectory for our interplanetary space probe to the edge of our solar system.
Considering that Pluto isn't that far, only 4.67 billion miles/7.5 billion kilometers, how can it be we
seem to know more about stars double, triple, quadruple the distance? We often don't 'see' asteroids
of doomsday capacity until they hurtle by us just out of our path, and unbeknownst to the average
person we have probably escaped total annihilation many more times with just a bit too much
regularity. But despite this, we have managed to learn more about our universe while we still
struggle to learn about our own oceans.
Early on in our lives many of us become fixated on stars, as we should be. When we look at
the night sky we see a vast multitude of pricks of light that when we ask, we are told they are stars. If
we are so unlucky we are told that they are angels up in heaven watching over you, and you will feel
indefinitely guilty with all of those morally superior beings watching over everything you do. These
pricks of light, while they seem all about the same, vary widely not only in size but also age and
temperature and luminosity. They are thus classified by their luminosity and temperature, which also
invariably tells us something about their size as well as where they are in there lifecycle.
The types are best remembered using the following mimetic: Oh Be A Fine Girl Kiss Me.
Can you tell that astronomers consist of mainly lonely and hopelessly romantic men?
O type stars are the most
luminous and hottest, the smoking
Victoria Secret supermodel turned
actress with a sugar daddy triple
her age. Whereas M stars are the
coolest and least luminous, the
slightly androgynous and plain
looking bank teller with the
stripper name who cashes your
paychecks on Tuesdays after sneezing all over
them. We measure and compare luminosity in relation to our sun, the cute and practical soccer mom
on the block, which is represented with ☉. It is easier to understand by using a Hertzsprung Russell diagram (HR Diagram) to visually represent what this means. So what scientists, and kids
doing labs in science class, do is using the luminosity and type of star, chart it on the HR diagram.
Most stars, for most of their life, follow the rules and exist in what is called the ‘main sequence’.
This just means that their luminosity, star type, and surface temperature all match up. The star is
healthy and still a kickin'. All is Status Quo. But not forever, because everything is temporary in the
universe. As they age they begin to die, wandering off and around the diagram before finally ceasing
to exist. But where do stars come from? And how can they ‘die’?
In the aftermath of the Big Bang, there was a bunch of dust, dirt, debris, and elements
floating around in a big soup. All of this stuff is called Interstellar Material (ISM). There is no small
amount of ISM either; these clouds hold enough material to form a minimum of 100,000 stars and up
to, and maybe even beyond, a few million. If there is one thing the universe always succeeds in
doing, it is making your head spin with the immense numbers, distances, and quantities it produces
and uses. But back to stars. ISM is 99% gases/elements, 1% dust. ISM, mass wise, is comprised of
about 74% Hydrogen, 25% Helium, and that last 1% is mostly comprised of metals.
The formation of a star is crucial to the rest of its existence. Kind of like predestination,
without the whole Heaven/Hell thing, because as non-living entities stars can't exactly go to heaven
or hell. When stars form, the amount of ISM they accumulate determines the rest of their lives. So
all of the condensing is highly critical in determining not only how luminous they will be, but also
how hot, how long they will live, and eventually how they will die. 90% of the star's life will fall in
the parameters of the main sequence, but it is here in formation that determines what happens after
that.
How stars came to be in the beginning is anyone's guess, but they did. But nowadays, and
probably for the last 13 billion years, stars have come out of concentration of this Interstellar
Material (ISM) called Molecular Clouds. You might also know these stellar nurseries as a Nebula,
particularly a Star Forming Nebula. These clouds are barely above absolute zero (right around 10
Kelvin), as space is cold, and the density of all of the materials shields from stellar radiation and
allows basic molecules to form. Most of the compounds formed are H2O (Water), CO (Carbon
Monoxide), and H2 (Hydrogen Molecules). However more complex organic compounds such as
methanol and acetone, and possibly even formaldehyde. If you could smell these clouds, they would
smell nothing short of nasty. On the other hand, they are nothing short of breath taking, so the ability
to smell in this case is irrelevant.
Mystic Mountain,
located in the
Carina Nebula. The
colors seen come
from the presence
of different
elements: Oxygen
(Blue), Sulfur (Red),
Hydrogen and
Nitrogen (Green).
Taken by The NASA
Hubble Telescope,
February 2010
These molecules form, in different regions of the molecular cloud, and as they do so they
begin to create heat. The pressure of the gas makes it hotter too. Soon you have all of these hot and
bothered atoms and compounds running around making it hotter, and BAM. They begin to collide.
And they stick together. Then larger clumps of gas and atoms form what are called protostars. It's
like the fetus stage. It's getting there, you can see the little fingers and toes (if stars had fingers and
toes), but it still looks like a gross frog thing. In the case of stars, this is physically manifested by
beginning to emit microwaves and infrared radiation. Not as cute as little toes and fingers, but at
least it's not a gross frog looking thing. Stars are born in
groups called clusters, hundreds coming out of the same
Molecular Cloud. Eventually the gravity inserted in and
the pressure exerted out will balance and the gas will form
a 'solid' existence. Solid in the sense that the pressure and
gravity keep the star as solid as it could be. A star truly
becomes a star when the gas and elements that have been concentrating themselves becomes so
dense, pressurized, and hot that they kick start fusion.
Fusion is not Fission. Fission is what we have in our nuclear power plants: taking heavy
radioactive elements and splicing them for energy. Fusion only happens in stars like our sun. Two
atoms collide at high speeds and form a new element, and a little bit of extra energy on the side. This
is important because all of the elements in our universe are for the most part created in the miracle
factories we call stars. But we'll get to the dispersal of all these fun compounds in a little bit. Fusion
is important because it is how stars fuel themselves: the 'burning' of hydrogen and helium is how
they produce their light, heat, and energy.
Stars come into existence when they begin to fuel their existence with fusion. The biggest
and most luminous stars are born first, and there are only a few of these O and B Stars. As you go
down the line, more and more of each kind exist with the most common being M. Our Sun is a G.
Not as in a gangster, or bro though in a way our sun is a bro because without the sun we would be
dead. Because space is cold. And very dark. While stars are not themselves alive, they produce light
and heat and radiation that allows us to live. Without stars, we would have never existed, for they
not only create all of the elements that make up our existence, but they also provide the very energy
we need to survive. No stars, no light, no heat, no photosynthesis, no gravity, no evolution, no Earth
as we know it. We owe stars everything, yet they ask for nothing.
Because they are so dense stars have really strong centers of gravity, which cause them to
slowly drift away from their peers to other sources of gravity, like other stars, debris, and black holes
(aka gravity on crack-cocaine). Most stars exist in solitude drifting through the galaxy. Some,
however, exist in a binary or multiple star system, in which two or more stars rotate around each
other or a central point of gravity. Is it not romantic, a pair of literal star crossed lovers, too afraid to
bear the universe alone? The two stars sling shot around each other. The gravity that drew them
together throwing them away only to bring them back together again. However, sometimes there are
more than two. A love triangle forms. The Plot thickens. The three or more stars whip around each
other in the same way as the two, but in a chaotic mess. Two result are possible, inevitably. Chaos
cannot exist for long in a place as organized as the universe. A star or stars wander off, gravity
(love), not strong enough to keep them there. Or two stars collide. Like a car crash, how fast they are
moving determines the damage. If it's at a slower pace, in a place of low star concentration and not a
whole lot of gravity, they can merge without a whole lot of fuss. At a fast pace, say near a black
hole, then the collision is an incredibly violent affair. The two stars fall to pieces, shattered and
broken hearted, never to exist as a star again. Or, with some types of stars, their collision can create
black holes and they drag everything down with themselves. But stellar collisions are not so
common, at least to us because the universe operates in billions of years, and as a result our fleeting
existence makes it difficult to speak with authority on these things. But we do understand the
mainstream life of stars.
Stars take one of two paths in life, that of the massive star or that of an average star.
The average star is well, average. They live somewhere between 500 and 200,000 million
years. That means some M class stars have not 'died' yet since the beginning of things. Stars run on
hydrogen, it is their everything. It takes all of its hydrogen in its core and uses the collision of all of
those atoms to fuel itself. In fueling itself it creates new, heavier elements. As it does so the core gets
more and more dense and eventually, the core is all helium. No more hydrogen. But pressure has
been building. And helium is close enough to hydrogen. With enough pressure the star will use
helium to sustain itself. This it does through shell burning, literally a thin shell encompassing the
core. Meaning that the star keeps on trucking. However,
this also causes the star to swell in size, like how you do
after eating a fantastic holiday meal with two helpings of
dessert to boot, with helium being that fattening dessert.
Thus the star enters the Red Giant Phase. The star goes
into as many rounds of shell burning as it can, before all
the unburned outer layers of the star is cast off and enters
the stage of planetary nebula. The core condenses and contracts and the drifting outer layers are lit
up as they are hit with ultraviolent from the now exposed core. Planetary Nebulas are very
picturesque and have a habit of looking like eyes.
But they are temporary, as are all things in the universe. The layers drift away and the
elements created by the star return to the ISM and drift though the galaxy. The core however has
now entered its last phase: white dwarf. Small and hot, these former cores slowly fade into oblivion
eventually becoming dark matter.
The Ring Nebula, also known as
Messier 57. Red is ionized
nitrogen, Green is ionized oxygen,
and Blue is super hot helium.
Taken by The NASA Hubble
Telescope, October 1998
While this sounds imposing and terrifying, in reality it is not. Dark matter is simply all the
things in the galaxy, or universe, that are not illuminated and therefore we cannot see. Not only does
the average star fade into oblivion, it fades into obscurity never to be known again. But stars, unlike
us, take this fate with elegance and grace. It's not like they have a real choice in the matter. It's been
predestined since birth. And they aren't alive, as far as we know, and therefore cannot do anything to
switch up their path in life. But even as living creatures, sometimes we have no more control over
our supposed fate and destiny than stars. Maybe it's simply all part of being made up of stardust.
Massive Stars follow a similar life path growing into red super giants, going through many more
rounds of shell burning, creating significantly heavier elements beyond helium including: carbon,
oxygen, magnesium, sodium, neon, silicon, sulfur, phosphorus, iron, and nickel. Just to name a few.
In the end these massive stars have not only gotten huge but in a last ditch attempt to suck up any
last bits of hydrogen they can begin to pulsate, to throb, to swell and shrink in size. Then the star
goes supernova sometime between the young age of 3 million and 15 million. The core begins to
compress and contract down and upon hitting maximum saturation, the smallest it can get, the outer
layers hit the super condensed core and begin to heat rapidly as they all pile up. It is in this
superheated moment that metals like gold, uranium, and platinum are formed. Then the gases and
elements superheated and heavily pressurized exploded outwards into space. The core collapses
down in less than 1 second. It takes about 15 minutes for the star to build up to its supernova. The
explosion itself lasts around100 seconds. The supernova creates a fantastic image too, visible for
many days after the incident, sometimes over a year. In space time, these stars die faster than a blink
of an eye. In blinking, the universe might miss it. Thankfully, no supernovas have occurred in our
neck of the galaxy or else we would be dead from the potent and concentrated gamma rays that shoot
out.
From here two option remain for the core remnant, the condensed and now exposed former
core. For the cores of less mass, contraction and collapse eventually stops and they create a neutron
star. These hella dense little suckers, like the white dwarfs, slowly fade into oblivion, but shoot out
x-rays and can have a powerful impact on the space around them causing gravitational magnetic
distortions. They can be so powerful that they distort the shape of atoms. If the core remnant is
larger, however, then it keeps collapsing in on itself to a super compact point called a black hole. It's
called a black hole because the velocity you need to escape the sheer gravity of the phenomenon is
greater than the speed of light. And nothing is faster than the speed of light. Yet. Meaning if you
were to stumble into a black hole, there would be no way out. You would suddenly be sucked into
universe time, as you looked around you would see everything moving fast. You would miss
supernovas, and some stars would live and die in what would seem like a matter of hours.
Cassiopeia A, a well examined Supernova remnant over 10 light years across. This image is
a false color image, a compilation of multiple exposure of different wavelengths.
Taken by The NASA Hubble Telescope, Spitzer Telescope, Chandra X-ray Observatory in
June 2005
While the remnants of the core are important, for our sake what is most crucial to our
existence is the outer shells that these stars shed as they die. The gases and elements in them return
to the ISM and clump back together into clouds and keep the cycle going. However, not all do so.
These elements drift through the galaxy and somehow, by some means, ended up on our tiny little
rock of a planet. We come out of the gelatinous muck that congregates on our rock in the sky and
over the next 4.5 billion years, humanity evolves to exist as you and I know it so that we can be
born. So that we can breathe. So that we can dream. And Love. And simply be.
So whenever you are having a slow and sad day and are feeling insignificant in this world:
Remember, you are the stuff of stars and that in of itself, is nothing short of beautiful.
"Though my soul may set in darkness, it will rise in perfect light, I have loved the stars too fondly to be
fearful of the night."
-Sarah Williams