What is the nebula all about?
The nebulae are distinguished by being large clouds consisting mainly of gas and dust. The gas that it forms is mainly hydrogen and helium. However, nebulae are not always the same. For this reason, we find several types of nebulae, which vary according to their characteristics and their origin. We also find nebulae with totally different origins. Such is the case of nebulae from which stars are born and nebulae that form when a star dies.
Examples of nebulae
Hundreds or thousands of nebulae can be seen in the sky. Adjacent stars excite the gas in the nebula, resulting in ionization. In this way, the gas in the nebula is capable of exposing light at different wavelengths according to the gas that forms them and the energy it receives from the surrounding stars.
These in particular do not receive enough energy from nearby stars to emit their own light. However, they have the ability to reflect the light of nearby stars. These nebulae are generally bluish in color. However, we can find reflection nebulae of other colors as in the case of Rho Ophiuchi.
These kinds of nebulae are difficult to observe, because they are not as bright. The typical example of reflection nebulae is found in the pleiades. This cluster of stars still shows parts of the nebula from which the stars have emerged. Specifically, these young and bluish stars are the ones that illuminate the gas cloud that remains around them. From a dark sky and through a telescope we can visualize nebulosity surrounding the cluster of stars.
This type of nebula has a main characteristic and that is that they shine with their own light. Nearby stars excite the nebula gas, resulting in ionization. In this way, the gas in the nebula is capable of receiving light at different wavelengths depending on the gas that makes it up and the energy that the surrounding star receives.
These nebulae are usually the brightest and most spectacular . It is characterized by its irregular shape, however, it will always appear surrounded by stars. This kind of nebula predominates in the vicinity of the galactic center, so during the summer is when we can visualize much more.
Emission and reflection nebulae
This classification is not closed and, on certain occasions, there may be nebulae that fall into one or more categories . A clear example of this is the ntren nebula in one or more sorion categories, which mixes emission and reflection regions. The center of the nebula is illuminated by the young stars that make up the popular trapezoid, while the rest of the nebula exposes its own Light. In fact, it is one of the brightest and most spectacular nebulae that can be seen in the sky.
Dark and absorption nebulae
Dark nebulae are not linked to any stars. Therefore, they are not ionized or reflect the light of any star. Thus, a dark nebula is an area of dust and gas that does not shine or emit light. Through the telescope it will appear as a dark region that hides the stars or the gas behind it.
They are very different from the rest of the other nebulae due to their origin. Although, they are emission nebulae, since the gas cloud shines by itself as it is ionized by the energy emitted by the remains (the white dwarf) of the stars that form it. In this case, the gas cloud is formed thanks to the gradual and unstoppable growth of the outer layers of the stars, until reaching the point where these layers are completely divided from the stellar nucleus.