NUCLEOSYNTHESISNUCLEOSYNTHESIS

WHERE DID ELEMENTS COME FROM?

Our universe started with aOur universe started with a BIG BIG BANG.BANG.

big bang n. (cosmology) the cosmic explosion that is hypothesized to have marked the origin of the universe.

After the BIG BANG, the universe started to

expand.

The first seconds after the BIG BANG, it was very hot.

Then, the universe started to cool down.

Right after the BIG BANG, the p+, the n0 and the e- were flying

around without control.

When it started to cool down, the quarks started making primitive elements:

1H1Hydrogen, 1 proton

1H2Hydrogen, 1 proton, 1 neutron

2H3Helium, 2 protons, 1 neuron

2H4Helium, 2 protons, 2 neurons

Those elements started forming stars.

Star n. a self-luminous gaseous spherical celestial body of great mass which produces energy by means of nuclear fusion reactions .

In the stars, because of high pressure, the elements started bonding and forming heavier elements

HOW WILL WE END?

WE all star

We all started with the BIG BANG…

… but how will we end?

Some scientists are sure that the universe will continue to

expand forever.

However, there is a theory that our universe will end in

“big crunch”

It states that someday the universe will stop expanding

and crunch together.

There is no proof for that theory.

Classifying Stars

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TO RECOGNISE STARS, SCIENTISTS HAVE TO CLASSIFY THEM

STARS ARE CLASSIFIED

BY

TEMPERATURE

COLOR

size

size

size

size

brightness

If the star is blueblue, it means it

is very hot . (≈50,000 C°)

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ColdCold stars are stars are redred.

The biggerbigger or hotterhotter the star is, the brighterbrighter it is.

Brightness is measured in 2 ways:

apparent brightness apparent brightness (brightness seen from earth)(brightness seen from earth)

absolute brightness (the “real” absolute brightness (the “real” brightness of the star)brightness of the star)

Stars are mostly made out of hydrogen.

Helium is about ¼ of the stars’ composition.

Enjar Hertzsprung and Henry Norris Russell made a diagram that classifies stars.

The hertzsprung-russel diagramThe hertzsprung-russel diagram

stars

temperature

size

color of star

Scientists measure Scientists measure distance between distance between

stars using stars using parallaxparallax

Parallax n. apparent change in apposition of an object when you look at it from different places

Scientists watch the positions of stars during different times of the year to figure out it’s position.

LIVES OF STARS

Stars do not do not live forever.

The larger a star is,

the shorter its life is.

Stars are born in nebulas.nebulas.

Nebula n. a large cloud of dust in space

Gravity pulls dust together so it forms a protostar

Protostar n. an early stage in the evolution of a star, after the beginning of the collapse of the gas cloud from which it is formed, but before sufficient contraction has occurred to permit initiation of nuclear reactions at its core.

As the protostar gets denser and denser, it forms a star

as the star becomes older, it

becomes a red giant

red giant= star uses up

its energy and becomes cooler, so it expands

Layers of the red giant fall off, releasing dust and gas into space.

It is called a planetary nebula.

The remaining star is very densedense and

brightbright.

It is a white dwarf.

When a white dwarf stops glowing, it is called a black black dwarf.dwarf.

high-mass stars are different.

When they die, they make a supernova – a

giant explosion.

After the supernova, the star becomes either a neutron starneutron star or a black hole.black hole.

a neutron stara neutron star: a white dwarf that has

very high pressure and temperature

A black hole is a neutron star with gravity so strong that

nothing, even light, can escape.

CAREERS

Nucleosynthesis is been studied by physicists

and astronomers.

www.nasa.gov

http://www.dictionary.net/big+bang

http://dictionary.reference.com/browse/star

http://www.wolaver.org/Space/abell39nebula.jpg https://segue.atlas.uiuc.edu/uploads/ryemm2/heic0409a.jpg http://www.janis.or.jp/users/kitahara/sww/rigel-z.jpg http://www.dorlingkindersley-uk.co.uk/static/clipart/uk/dk/sci_space/image_sci_space013.jpg http://www.mauthelimited.com/Assignments/Dreamweaver/Science_Class/Images/stars/whitedwarf_star.jpg http://cse.ssl.berkeley.edu/bmendez/ay10/2000/cycle/redgiant.gif

http://www.agdesktop.com/wallpapers\space\nebula\nebula-0006.jpg http://www.abc.net.au/unleashed/images/OpenBook_Stock_400.jpghttp://techlibrarian.files.wordpress.com/2009/06/horsehead-nebula2.jpg