Information gathered from the MIT web site and NASA
Extra resources
What is a Star?
Stars are hot bodies of glowing gas that start their life in Nebulae. They vary in size, mass and temperature. The color of a star is determined by its temperature, the hottest stars are blue and the coolest stars are red. The Sun has a surface temperature of 5,500 degrees Celsius, its color appears yellow.
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Stage
1- Stars are born were there are lots of small stars called a
Nebulae. The star is born when gas and dust collect in one spot and contracts with
the weight of it's own gravity.
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2- After the dust and gas collect, it will begin to heat up and
start to glow forming Protostars. If
a protostar contains enough matter the
central temperature reaches 15 million degrees centigrade.
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Stage 3 -
At
this temperature, nuclear reactions in which hydrogen fuses to form helium can
start. The star will continue to glow and it will begin to create it's own
energy. Most of the protostar cloud has vaporized to
reveal the core. This stage is called Pre-Main
Sequence.
Video
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| Stage 4 - The star begins to release energy, stopping it from contracting even more and causes it to shine. It is now a Main Sequence Star. |
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| Stage 5 - A star of one solar mass remains in main sequence for about 10 billion years, until all of the hydrogen has fused to form helium. Our own sun is in this stage. |
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Stage 6 - The helium core now starts to contract further. Reactions begin and a shell is formed around the inner core as it constricts.
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Stage 7 - Towards the end of a star's life, the temperature near the core rises and this causes the size of the star to expand. The core is hot enough for the helium to fuse to form carbon. The outer layers begin to expand, cool and shine less brightly. The expanding star is now called a Red Giant. |
| Stage 8 - The helium core runs out, and the outer layers drift away from the core as a gaseous shell, this gas that surrounds the core is called a Planetary Nebulae. |
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Stage 9 - The core becomes a White Dwarf the star eventually cools and dims. This star has exhausted most or all of its nuclear fuel and has collapsed to a very small size; such a star is near its final stage of life. When it stops shining, the now dead star is called a Black Dwarf.
Resources
MIT
History
of the Universe
Chandra telescope
