StarsTwitter: @LilyKotze

large balls of gas

Stars are

that radiate light.

Large quantities of energy come from hydrogen nuclei colliding to form a Helium nucleus. This is called nuclear fusion.

Stars exist for a limited time.

Stars form inside nebulae, which are pulled together by gravity.

Nebulae: Large clouds of dust and gas.

born,When a star is it is relatively cold.

As gases are compressed due to gravity, temperature increases.

When temperatures are high enough,

nuclear fusion reactions

occur.

Hydrogen nuclei join up.

Large amounts of energy are radiated into space.

changes

In the early phases, these stars are known as protostars. They are often known as brown dwarfs.

Stars change in appearance over a very long time.

Stars that look blue are hotter and usually younger than stars that look red.

Our sun is about halfway through its life cycle.It is a medium-sized yellow star.

Towards the end of the life of a sun-like star,

it will swell up to form red giants.

Life

A red giant is a massive star: • Small to medium size mass.• Later stage of life• Nuclear fusion: in the shell, on the outside of

the core.• The gases in the core are extremely

compressed.• The outer atmosphere is swollen and sparse.• The tail of the star is enormous.• The surface temperature is low.

Death

Some time to the end, the nuclear reactions run out of fuel.

For stars like our sun, the core contracts to

become a white dwarf.

The outer gases of the star are ejected into space.

They become an expanding cloud around the white dwarf.

Planetary nebulae are lit up by their central white dwarf.

White dwarfs that are isolated can, cool down and become dimmer until they eventually are invisible.

They are then called black dwarfs.

The heavy elements that are created by stars are the start of the next stars.

Title: https://farm6.staticflickr.com/5442/9076385353_8a75f19806_o_d.jpg Slide 3: http://spaceplace.nasa.gov/review/story-superstar/page13.png ; fusion: http://fusionforenergy.europa.eu/understandingfusion/whatisfusion/Whatisfusion_2.jpg ; joke: http://mrdclassified.weebly.com/uploads/1/3/5/0/13508015/627364475_orig.jpg?164 Slide 4: http://sci.esa.int/science-e-media/img/5a/Herschel_Hubble_Crab_Nebula_highres.jpg Slide 5: Hydrogen: http://theodoregray.com/PeriodicTable/Samples/001.x3/s15s.JPG ; Helium: http://periodictable.com/Samples/002.6/s13.JPG Slide 6: http://exoplanet.as.arizona.edu/~lclose/teaching/a202/disk-lr.jpg Slide 8: http://whyfiles.org/wp-content/uploads/2013/06/sun_diagram.jpg Slide 9 : http://kepler.nasa.gov/files/mws/kasc3.jpg Slide 11: http://www.nasa.gov/images/content/49887main_stellar2.jpg Slide 13: Helix nebula: https://upload.wikimedia.org/wikipedia/commons/b/b1/NGC7293_(2004).jpg Slide 14: http://scienceblogs.com/startswithabang/files/2011/09/star_dwarf_5.jpeg Slide 15: http://www.einstein-online.info/images/spotlights/redshift_white_dwarfsI/wd_comp.gif Slide 16: http://headwatersacademyearthsci.weebly.com/uploads/2/1/9/1/21919828/411679_orig.jpg