Nebulae are a complex gas and dust collection that entered Turkish as nebula. Although it is said to be formed mainly by hydrogen and helium gases, other gases also have an effect on the formation of nebulae. All the stars in the universe were formed in nebulae. Therefore, nebulae are very important for the formation of stars and star systems.
Nebulas are categorized according to the way they occur. These are known as Emission Nebulae, Dark Nebulae, Supernova Nebulae (dead star remnant), Planetary Nebulae, and Reflection Nebula. To examine according to their formations;
The amount of hydrogen in the Emission Nebulae structure is slightly higher than the others. They emit light at a certain frequency due to interactions between electrons (electrons transition from their current energy level to a lower energy level). For this reason, they are known for their red or red undertones. In this case, we conclude that Emission Nebulae tend to produce light rather than reflect it. The most common emission nebula results from the ionization of O- and B-type stars with a dense neutral hydrogen atom. It is the closest type of nebula to Earth, and the best-known example is the Orion Nebula.
Dark Nebulae get their name because of their density. These nebulae, which have a very dense structure, pass very little light. This causes us to observe them as blackouts. A solitary Dark Nebula is very difficult to spot. It usually co-occurs with the Emission Nebula and the Reflection Nebula. It is also called the Absorption Nebula because it does not transmit light. In fact, the reason why it does not pass light (visible) is due to the dust particles it contains. These dust particles have the ability to absorb light. Consequently, if we want to observe the Dark Nebula, we will need infrared lights. The best-known Dark Nebulae are the Horsehead Nebula in Orion and the Coalsack nebula in Crux.
Reflection Nebulae, as the name suggests, do not produce light internally, but rather reflect the presence of a nearby star. It is a type of nebula that reflects the light it emits. The brightest Reflection Nebula is where a new star is forming. It is colder than other nebulae. However, if it coincides with the formation of a new star, it can rise to almost twice the surface temperature of the Sun. It is known that the mass of a nebula in this phase can be 3.5 times greater when compared to the Sun. One of the best examples is the Trifid Nebula (also called M20).
Supernova Nebulae are formed as a result of the massive explosion of massive stars at the end of their lives. It may actually look more like a death nebula than a birth nebula. For this reason, they are known as remnants rather than nebulae. Since the destructive power caused by the violent explosion is high and irregular, dust and gas particles are scattered randomly in the space. Randomly dispersed particles are the most important features that distinguish Supernova Nebulae from Planetary Nebulae. Planetary nebulae, in contrast to Supernova, exhibit a highly ordered and symmetrical behavior. The best known Supernova remnant is the Veil Nebula.
The naming of Planetary Nebulae can lead to misunderstandings that it is composed of planets, as it was made by the inexperience of the early periods of astronomy history. But that’s not the case, and Planetary Nebulae have nothing to do with planets, contrary to popular belief. The Planetary Nebula is known as a late-end nebula because it is low in mass and has consumed all its fuel. The nebula is known for the effect of the star, which begins to release its surface layers into space during this phase. In fact, as a result of nuclear fusion reaching extreme dimensions, it loses its hydrostatic balance and begins to swell. The next is the red giant stage. The most familiar Planetary Nebula is the Helix Nebula.
Author: İsra Feza Cried