Life cycle of a star
Stars are born in nebulae. Huge clouds of dust and gas collapse under gravitational forces, forming protostars. These young stars undergo further collapse, forming main sequence stars.
Stars expand as they grow old. As the core runs out of hydrogen and then helium, the core contacts and the outer layers expand, cool, and become less bright. This is a red giant or a red super giant (depending on the initial mass of the star). It will eventually collapse and explode. Its fate is determined by the original mass of the star; it will become either a black dwarf, neutron star, or black hole.
NEBULA -A nebula is a cloud of gas (hydrogen) and dust in space. Nebulae are the birthplaces of stars within the nebula there are varying regions when gravity causes this dust and gas to stick together. STAR -A star is a luminous globe of gas producing its own heat and light by nuclear reactions (nuclear fusion). They are born from nebulae and consist mostly of hydrogen and helium gas. the corresponding colours from red to blue-white.. They live for less than a million years before exploding as supernovae. The faintest stars are the red dwarfs, less than one-thousandth the brightness of the Sun. RED GIANT-This is a large bright star with a cool surface. It is formed during the later stages of the evolution of a star like the Sun, as it runs out of hydrogen fuel at its centre. They are very bright because they are so large; Very large stars (red giants) are often called Super Giants. RED DWARF- These are very cool, faint and small stars, They burn very slowly and have estimated lifetimes of 100 billion years. Proxima Centauri and Barnard's Star are red dwarfs.
WHITE DWARF-This is very small, hot star, the last stage in the life cycle of a star like the Sun. The surface temperature of a white dwarf is 8000C or more, White dwarfs are the shrunken remains of normal stars, whose nuclear energy supplies have been used up. White SUPERNOVA -This is the...
Please join StudyMode to read the full document