WE ARE MADE OF WE ARE MADE OF STAR DUSTSTAR DUST

It all started with the It all started with the Big BangBig Bang (a (a scientific theory) 13.7 b.y.a. scientific theory) 13.7 b.y.a.

HydrogenHydrogen and and HeliumHelium were formed were formed..

So what IS Star dust?So what IS Star dust? Elements = chemical elements that we find on Elements = chemical elements that we find on

the periodic chart. It starts with the tiny H the periodic chart. It starts with the tiny H (hydrogen) . Check out your periodic chart!(hydrogen) . Check out your periodic chart!

Are we truly made up of stardust or Are we truly made up of stardust or where are all the elements formed? where are all the elements formed? a)In Big Bang (H, He)

b)In Stars

c) In Supernovae and Novae Explosions

( Man-made elements –not found in our bodies or nature)

All these main elements in our body All these main elements in our body were created in space! And then some!were created in space! And then some!

Stars create chemical elements through fusion – the same elements we find on Earth.

Recipe for Fusion:

1.Take some small elements.

2. Let them be pulled into the center by gravitational force.

3. Apply LOTS of pressure

3. Apply HIGH HIGH heat.

4. The nuclei of protons and neutrons will combine and form one nucleus.

5. The electrons will match in number the protons and electrons.

6. The “left overs” (positrons, neutrons) and energy (gamma rays) escape.

http://aether.lbl.gov/www/tour/elements/stellar/stellar_a.html (excellent article)

What are the elements formed in a star?

• The smallest elements are formed from what into what? _______ ______

• The largest element formed in a star are _______ .

• Our sun may be too small to produce all these elements. True/False?

• Do stars produce the most abundant elements organisms need? Yes/No? What are they? ____ _____ _______ _____

Larger elements get formed as part of nova and supernova events

• A nova or supernova is the explosion of a huge dying star’s contents.

• Lots of pressure, lots of heat• Lots of larger elements are formed.• Which ones? List some by consulting your

periodic chart: __________________http://aether.lbl.

gov/www/tour/elements/stellar/stellar_a.html (excellent article)

Orion’s Horsehead

Nebula• A: Nebulae are clouds of

gas and dust made up of chemical elements (H, He, O, C, Fe ..) that were created shortly after the big bang or are left-overs from violent supernovae explosions.

• A: In areas where dust and gas condense further, new star and solar systems are born out of this material.

How is this nebula picture created? Painstakingly.

• http://www.pbs.org/wgbh/nova/origins/hubble.html

Q: What IS a Nebula??

Q: Where in a Nebula do new Stars get born?

What is a nebula made up of?

• Nebulas consist of mostly ____ and ____ elements, but there is a whole smorgasbord of other elements in them as well.

• These elements are part of the ____ and ______ that make the nebula look like a cloud.

• Only (dense/loose) _______ regions of nebula can “give birth” to new stars.

• As these regions rotate (like eddies) and condense further, matter meets and forms larger structures.

As material rotates and condensed, two things happened:1. Motion forms a disk

2. The speed of rotation increased, hurling the heavier materials into the center where they heated up and up.

The Solar system – the sun and the nine planets – started off as a spinning cloud composed of its nebula’s

gas and solid grains of ice and rock. When the sun formed, its heat evaporated the icy grains near it, leaving only rock that grew into our small rocky planets. Further out, the icy grains survived, next to some rock, and the planets that formed attracted extra gas to be built into our gas giants

Review Q:

1. HOW did your Solar System develop?

2. Why is there no ice near the sun but far out by the gas giants?

3. Why is there no gas by the terrestrial planets?

4. Why does our planet have liquid water (and ice and water vapour) but the others don’t?

We Are Made of Stardust• Big Bangs produced the H and He.• Stars form chemical elements (He, C ..) through fusion in their

center.• At the end of their life stars explode and free these elements that get

collected into nebulae.• Nebulae are nurseries of new stars and solar systems now contain

these elements.• Our solar system also “inherited” these elements. So when Earth

formed, these elements were its building blocks.• And we humans, earthlings, are made up of just these same

elements ( H, He, C .. ) made once upon a time and put into the nurseries of stars, the nebulae..

• Cycling of Matter recycles these elements – our stardust – over and over again.

• We are made of Stardust – we are components of the Universe.

Recycling = Renewal

• Matter (elements in gas or dust form and other components) in the Universe are recycled through formation of stars and supernova events that produce the nursery for new stars. Where these stars produce new matter and explode and so it goes on and on for a while.

• Recycling of Matter in our biosphere is equally important, as the next slide demonstrates.

Non-living thingsWater

Carbon dioxideNutrientsSunlight

Primary producer

Primary consumer

Secondary consumer

Decomposer

Cycling of Matter ensures that our elements – stardust

get reused

How does light get How does light get produced?produced?

The sun produces light through The sun produces light through fusionfusion..

The moon and other shiny things The moon and other shiny things reflect lightreflect light that is produced from that is produced from another source.another source.

Most light bulbs produce light Most light bulbs produce light through incandescence or through incandescence or fluorescence. fluorescence.

How the Sun produces light.How the Sun produces light.

+ Fusion

Reflected lightReflected light

Earth

Earth, our moon and close objects are lighted up by the sun where and when it shines on it (our daytime!).

Earth’s Light is

Incandescent lightsIncandescent lights

Light is produced by heating up a wire with electricity until it is white hot.

90 % of the energy transformed as heat. Only10% of the total energy is transformed as light.

Fluorescent lightsFluorescent lights

The Fluorescent lights work because a ballast gives a high initial voltage to start an arch within the tube. The current is then reduced to just maintain the electric arc. In the lamp the electric arc between the two electrodes excites atoms of mercury present in the gas fill in the lamp, causing electrodes in the mercury atoms to absorb energy and then release it in the form of ultraviolet (UV) radiation.

This UV light then strikes the phosphorus coating the inside of the lamp tube which “Fluoresces” , producing visible light.

Glow in the Dark StuffGlow in the Dark Stuff

Photons (light particles) are absorbed by phosphors and released at a slow rate, after the light source has been removed.

The two chemicals used today are Zinc Sulfide and Strontium Aluminate.

The Sun produces as part of fusion far more than just Light: it produces lots of Energy!

+

The Sun (a star) produces the Whole ELECTROMAGNETIC SPECTRUM = energy!

Elements in the Sun: 4 hydrogens fuse to 1 Helium atom and energy.

Going further: Thermonuclear Reactions in the Sun

1H1 + 1H

1 1H2 + 1e

0

____________________________________________________________________

1H2 + 1H

1 2He3 + (gamma) radiation

____________________________________________________________________

2He3 + 2He3 2He4 + 1H

1 + 1H1

____________________________________________________________________

In the first reaction, 2 Protons combine to formdeuterium and a positron. One of the protons isconverted into a neutron and a positron.

Proton Neutron Positron

______________________________________________________________________

In the 2nd reaction a proton + deuterium unite toform the light isotope of helium, 2He3

____________________________________________________________________

The first two reactions must occur twice for the 3rd

reaction to occur.

_____________________________________________________________________

1e0

Summary of Solar Fusion Reactions

1H1

1H2

1H11H1

1H2 Energy

2He3

2He3 2He3

2He4

THE SUN: A PERFECT FUEL THE SUN: A PERFECT FUEL FOR LIFE ON OUR FOR LIFE ON OUR BLUE BLUE

BEAUTYBEAUTY

BLUE BEAUTYBLUE BEAUTY

Can we run out of energy? Yes, Can we run out of energy? Yes, should the sun no longer shine.should the sun no longer shine.

THE ENDTHE END