09+STAR+LIFE+CYCLES+AND+GRAVITY


 * //3.11 Describe the evolution of stars of similar mass to the Sun through the following stages://**
 * //a) nebula//**
 * //b) star (main sequence)//**
 * //c) red giant//**
 * //d) white dwarf//**
 * //3.12 Describe the role of gravity in the lfie cyle of stars.//**
 * //3.13 Describe how the evolution of stars with a mass larger than the Sun is different, and may end in a black hole or neutron star.//**

__ Evolution of Stars and Gravity __


 * # ======Stellar evolution begins with the gravitational collapse of a giant molecular cloud. As it collapses, a GMC breaks into smaller and smaller pieces. In each of these fragments, the collapsing gas releases gravitationalpotential energy as heat. As its temperature and pressure increase, a fragment condenses into a rotating sphere of superhot gas known as a protostar. ======
 * 1) A **red giant** is a luminous giant star of low or intermediate mass. The appearance of the red giant is from yellow orange to red, including the spectral types K and M, but also class S stars and most carbon stars. The most common red giants are the so-called red giant branch stars (RGB stars) whose shells are still fusing hydrogen into helium, while the core is inactive helium.
 * 2) ======**(THE SUN WILL BE A RED GIANT IN AROUND 0.5 BILLION YEARS)** ======
 * 3) A **planetary nebula** is an emission nebula consisting of an expanding glowing shell of ionozed gas ejected during the asymptotic giant branch phase of certain types of stars late in their life.  ||

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[] - extremely good website, with explanations and diagrams of things you need to know on this subject. ======

GRAVITY IN STARS All stars exists in a constant balance of gravity squeezing them smaller and the nuclear reactions in their cores trying to make them explode apart. Gravity eventually wins as stars run out of nuclear fuel to keep them going.

Put this into perspective on Earth if you fall off a 1 meter ladder you would hit the ground at roughly 7mph now if you fall off that same ladder on a neutron star (which is roughly 12km in diameter) you will hit the ground at a whopping 1.5 million mph.

A black hole is the ultimate triumph of gravity over matter. This region of space has such strong gravity that not even light can escape. They are usually 2 times heavier than the Sun and are mostly formed from the death of massive stars. Gravity is imminent on the largest scales, shaping planets and stars, as well as the small things that many people don't notice, such as the Moon's gravity changing the tides. 