Monday, November 14, 2011

the stars




Stars!!;)

What is a star?
Stars are large balls of hot glowing gas, and they have various different sizes and colors. Stars can be orange, blue, red ,yellow and white. Some stars are bigger than the sun, which is also a star. Even though they look really small up in the sky, they are apparently really big. Stars are either bright or dim and they also either cold or hot.

Type of star

Type of stars
They are four different types of stars:
 1)Super Giants are middle ages, medium, large, orange, cold and bright stars. Super Giants' spectral class stars from A to M.
2)Giants are middle ages , small, medium, red, cold, bright and dim stars. Giants' spectral class starts from G to M.
3)Main Sequence are middle, medium, white, yellow, orange, hot, cold stars. Main sequence’s spectral class starts from O to M.
4)White Dwarfs
are old, hot, medium, blue and white stars. their spectral class stars from B to F.
H-R Diagram
Map Astronomers used to classify stars by their luminosity, name, size  temperature , color, type and spectral class. It helps them distinguish stars in different categories.
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Nuclear fusion
when a star change hydrogen gas molecule into helium molecule and creates energy. Stars make their energy from nuclear fusion.

 
Life cycle of a star
first they were Stella Nebula, a big giant cloud of dust and gas. Gravity shrinks the clouds. it creates sun like stars, huge star and giant stars.from sun like stars , they became red giant, then planetary nebula( a cloud of gas and dust), later white Dwarf, it gets smaller and smaller and turn into black dwarf(a cold, dark object)
From Giant stars, it became red super giants, then supernova and finally black hole( when star collapse after an explosion)
 
from huge stars, it became red giants, then supernova( a giant explosion caused when stars burst) and last Neuron star( a small, dense object that spins very fast)