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Nebula By: Mckayla Morrison
What is a Nebula? • A nebula is an interstellar cloud in outer space that is made up of dust, hydrogen and helium gas, and plasma. It is formed when portions of the interstellar medium collapse and clump together due to the gravitational attraction of the particles that comprise them. Rather, it is made up of gas and dust known collectively as the interstellar medium or ISM. So, it is this dispersed matter that eventually collapses and forms a nebula.
What are the 5 types of nebula? • Reflection Nebulae • Emission Nebulae • Dark Nebulae • Planetary Nebulae • Supernova Remnant
Reflection nebulae • Reflection Nebulae have a very unique property. The dust and gas of this type of nebula does not emit its own light. Instead, it reflects light from nearby stars and/or galaxies. They are usually located near a really bright star in the sky.
Emission Nebulae • This type of star actually emits its own light, because of the radiation from stars within the nebulae. But the radiation emitted from the stars have a unique property. The radiation from the stars in the nebula is so strong that it can "excite" atoms that are within the nebulae, and the excited atoms will move from one energy level to the next. The result of this is the atoms emitting radiation as well.
Dark Nebulae • This type of Nebulae is different from a reflection nebulae and emission nebulae by which it absorbs some light from stars behind it. The light absorbed ends up heating the dust particles up, which results in the particles re-radiating, or emitting, some of the absorbed energy as infrared light.
Planetary Nebulae • Of all the nebulae described in this page, planetary nebulae are probably the most widely known nebula. They are formed when old stars of a size, similar to our Sun's size, have consumed most of their hydrogen fuel after billions of years. The star does not explode, but instead it ejects the gases at much lower speeds and at different times. As the star continues to cool and compress, the inner core of the star becomes very hot and explodes. The very high temperature radiation from the explosion causes the ejected gases to become radioactive. The end result is a star that glows.
Supernovae Nebula • Supernovae occur when a massive star ends its life in an amazing blaze of glory. For a few days a supernova emits as much energy as a whole galaxy. When it's all over, a large fraction of the star is blown into space as a supernova remnant. A typical supernova remnant is at most few light-years across. Where as a supernova is the explosion of a massive star.
What Causes A Nebula? • Gravitational instability of molecular nebulae causes formation of protostar, which evaluates to the star.Gravitational force causes the star nebula to begin to collapse in on itself. As the dust and gas come together, they begin to heat up. Eventually, the matter becomes so dense and hot that it forms a protostar. Protostars are not very stable and may not go on to be true stars. • If the gas within the protostar does not get hot enough, it will not achieve nuclear fusion and the protostar then becomes a brown dwarf.If the protostar contracts enough and becomes hot enough that it is successful in fusing its hydrogen into helium, it becomes what is called a "main sequence star." The fully grown star spends its entire lifetime, which can run to billions of years, fusing hydrogen. As it burns this fuel, it continues to slowly contract, which in turn causes it to heat up. When the star runs out of hydrogen it is at the end of its lifecycle. Massive stars may begin to fuse their helium and create other elements, such as carbon and iron, as byproducts.
How it Works! • 1. Gravity pulls gas and dust inward toward the core. • 2. Inside the core, temperature increases as gas atom collisions increase. • 3. Density of the core increases as more atoms try to share the same space. • 4. Gas pressure increases as atomic collisions and density (atoms/space) increase. • 5. The protostar’s gas pressure RESISTS the collapse of the nebula. • 6. When gas pressure = gravity, the protostar has reached equilibrium and accretion stops
