Where did all the Elements come from?Nucleogenesis and Fusion of Subatomic Particles

Reviewing the Beginning13.7 billion years ago

Extremely hot

Expanding “soup of particles”

Inflation: early phase rapid expansion

Cooling with steady, constant expansion

Nuclear Weak Force

Nuclear Strong Force

Cosmic Background Microwave Radiation

Baryons: Protons & Neutrons (made up of quarks)

Big Bang Fusion of nuclei Hydrogen (makes up 90% of the Universe today) Helium Lithium Beryllium

No electrons attached to these nuclei, they are too hot

Predominance of the lightest element = Evidence of the Big Bang

The Nuclear Weak ForceWhy don’t negatively charged electrons

fall into positively charged protons? THE NUCLEAR WEAK FORCE!! Neutron --> Proton + Electron!

The Weak Force is responsible for Initiating hydrogen fusion in stars the radioactive decay of subatomic

particleso Large nuclei are unstable

o β-decay: Neutrons fall apart to form a proton and an electron, the electron escaping into the orbital of the atom

Nuclear Strong ForceProtons are all positive and would love to repel

each other

The nuclear strong force holds the nucleus together You must have energy to exert a force. Nuclear energy powers the strong force.

Affects very small space

HUGE amount of energy – released in fission…bombs

Nuclear Strong Force: Squeezing a Nerf Ball

The nuclear strong force is like an invisible hand that holds the nucleus (Nerf ball) together.

Without it, there could only be Hydrogen in the Universe

FusionProton-Proton Chain

2 Hydrogen fuse to form Helium Helium fuse to form Carbon Carbon fuses with Hydrogen to form Nitrogen Nitrogen fuses with Hydrogen to form Oxygen…..

Requirements of FusionHeat-Heat-Heat

Gravity pulls the atoms together

Gravitational pressure heats the gases to millions of degrees

Mass - Stars: the bigger they are the hotter they are More Mass = More heat =

more fusion = more elements

H - He - C - O - Ne - Mg - Si - Fe

IronFusion in stars can form nuclei that have up to 26

protons = IRON Too much energy is required to overcome the

electromagnetic repulsion

• Creating elements heavier that iron requires more energy

Fusion also Creates Isotopes

Neutrons are captured by other atoms to form Isotopes

Isotopes are forms of standard elements with extra neutrons

The Heavier ElementsSupernova of extremely massive stars

Cores of these stars are saturated with iron Extreme pressure and temperature

Gamma radiation breaks the iron nuclei releasing more energy

Shock-wave produces enough energy to fuse elements heavier than iron up to and including Uranium

HOW DO WE KNOW ANY OF THIS????

The Electro-Magnetic Spectrum

Light PropertiesThe Speed of Light = c

3 x 108 m/s190,000 miles/second

Light could travel around the world about 8 times in one second

EM SpectrumSpectrum means “a range”

EM spectrum ranges from long wavelengths to short

Shorter wavelength = higher energy Highest energy waves are bad for our

bodies

EM WavesHave properties of waves…Crests & troughsReflect & refract (bend)

…and particlesCan travel through empty

space

Wavelength and Frequency

λ = Wavelength, the distance between 2 peaks (or troughs)

f =Frequency, the number of waves per second

Velocity of a wave, v = λf EM waves all travel at 3 x 108 m/s A longer wavelength means a lower

frequency A shorter wavelength means a

higher frequencywww.nasa.gov

The Speed of Light

c=

c = speed of light

= frequency

= wavelength of light

Hertz (Hz) = unit of frequency Hz = 1/ second

Wavelength is measured in units of length, meters to nanometers

Energy

As frequency decreases, energy increases

E = h h = 6.626 x 10-34 Joules *second

Energy Unit J = Joule = Watts/m2

Higher energy = higher frequency= shorter wavelength

Frequency

Energy

Light as a ParticleLight = photons

Photons are considered to be both particle and a wave

What does that mean?A photon is a “wave packet”A photon is a “light particle”

Electromagnetic Radiation and YouLight is sometimes called E-M radiation

All things emit E-M radiation

You emit radia-tion• RADIO • MI-

CROWAVES• Infrared

(heat)

The Visible Spectrum

violet 380-420 nm

indigo 420-450 nm

blue 450-495 nm

green 495-570 nm

yellow 570-590 nm

orange 590-620 nm

red 620-750 nm

Visible Light

Visible LightNot all animals see the same wavelengths as

humans

Some see shorter wavelengths (ultraviolet) Hummingbirds Bees Mantis Shrimp

Others see longer wavelengths (infrared) Bats Snakes …and Mantis Shrimp… they do have the best eyes

on Earth, unfortunately they have very small brains and probably do not appreciate what they are seeing…

Visible Light vs. UVFlower in visible light Flower in UV light

Visible Light vs. InfraredBats in infrared

lightBats in

visible light

Full Visible Spectrum

Red Orange Yellow Green Blue Violet

(Indigo)

What does this have to do with

Astronomy??

How do we know what a star is made of??

By looking at its EM spectrum

The star’s “fingerprint”

Hydrogen

How light or electromagnetic radiation is used in Astronomy

• Astronomers use spectroscopes separate starlight into its colors Identify star’s composition, temperature,

luminosity

• Different wavelengths provide different information Temperature – Blackbody Radiation Composition – Absorption Spectrum Luminosity/Brightness

Two Girls in the IRIs this in “true color?”

http://en.wikipedia.org/wiki/Infrared

Emission SpectraFull

spectrum

Wavelengths:

H

Models of a Hydrogen AtomPhET's Model of a Hydrogen Atom

Composition of stars