Mike Chris

The Life Cycle of Stars

Life of a Small to Medium-Mass Star

Stars begin as a nebula, or clouds scattered dust made mostly of hydrogen

As the nebula collapses the contents of it begin to to heat up. This is known as a protostar

This phase can be referred to as the fetus of the star

Nebulas And Protostars

http://www.godandscience.org/images/nebula.jpg

Brown dwarfs are objects in space

They are not technically stars, and are bigger than planets

Brown Dwarf

http://seanf.hypexr.org/project/Brown_Dwarf.jpg

Brown Dwarf

The main sequence is where stars live most of their lives

Right now, our sun is in the main sequence

A star begins the main sequence when nuclear fusion begins

Main Sequence

http://www.noaanews.noaa.gov/stories2005/images/sun-soho011905-1919z.jpg

Main Sequence Star

FusionNuclear fusion is when two atoms combine to make a larger one

In stars this is between hydrogen and helium

When a star runs out of hydrogen, it starts fusing helium and carbon

Larger stars can fuse carbon into even heavier elements like iron

When a star starts burning helium, it starts to pack the atoms tighter together, causing the outside of the star to expand

When this happens, it is classified as a red giant

This is the first step into old age

Red Giants

http://www.lancs.ac.uk/ug/hilditch/pic3.gif

Red Giant

Planetary nebula is a nebula that has gas and plasma

Planetary nebulas are made of dead starsAfter a red giant a planetary nebula is made

Planetary Nebula

http://en.wikipedia.org/wiki/File:NGC6543.jpg

Planetary Nebula

The cores of low-mass stars are white dwarfsWhite dwarfs are close to the size of the Earth, but

may weigh as much as our sunThey are not as bright as larger starsWhite dwarfs are very bright because of the heat

made when the star collapsedA black dwarf is made when white dwarf

becomes coldBlack have not been proven to exist because it

takes longer for a white dwarf to become one than the universe has been in existence

White and Black Dwarfs

http://cactus.dixie.edu/smblack/chem1010/images/Unit_4/4A_white_dwarf_star.jpgWhite Dwarf

Life of a High-Mass Star

Massive main sequence stars are the same as small or medium-mass except that they are bigger so they burn hydrogen faster

Massive Main Sequence

https://segue.atlas.uiuc.edu/uploads/ryemm2/blue%20main%20sequence.jpg

Massive Main Sequence Star

Supergiants are the largest stars in our universe

They can have a diameter of around 1,000 times bigger than our sun

Supergiant

http://isc.astro.cornell.edu/~sloan/fun/figures/star_agb.gif

Supergiant

A supernova is an explosion of a high-mass stars

This happens when a star’s supply of energy and light runs out

This only happens every few millions of years

Supernova

http://imagine.gsfc.nasa.gov/Images/bios/stecker/large.supernova.jpg

Supernova Remnant E0102-72

Neutron Star

A neutron star is the result of a supernova

A neutron star is small and dense and is mostly made up of neutrons , hence the name

A neutron star is bigger in mass than our sun

http://nrumiano.free.fr/Images/Neutron_star_E.gif

Black Holes

A black hole is another result of a supernova

It is a thing in space that has such a strong pull of gravity so strongly that light can’t be seen

Until recently, astronomers didn’t know that black holes even existed because black holes can’t be seen with a telescope

http://ucsdnews.ucsd.edu/graphics/images/2006/neutron-star-jet_bg.jpg

Black Hole

Why high-mass and low-mass stars live different livesHigh-mass and low-mass

stars take different paths at the end of their lives

High mass stars burn their fuel faster than low-mass stars, which is why low-mass star live much longer than high-mass stars

Also, high mass stars end their lives with a supernova, then a black hole or a neutron star

Low mass stars end their lives by becoming a white dwarf

http://www.geosociety.org/graphics/04denver/blackhole.jpg

Black Hole

Ages of Different Mass Stars

Most massive-20 million years

Our sun-10 billion years

Least massive-1 trillion years

http://www.keyway2.ca/jpg/stars.jpg

http://nasascience.nasa.gov/astrophysics/how-do-stars-form-and-evolve

http://sunshine.chpc.utah.edu/labs/star_life/starlife_main.html

http://simple.wikipedia.org/wiki/Supergiant http://simple.wikipedia.org/wiki/White_dwarf http://simple.wikipedia.org/wiki/Red_giant http://simple.wikipedia.org/wiki/Black_hole http://simple.wikipedia.org/wiki/Main_sequence http://simple.wikipedia.org/wiki/Neutron_star

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