The word nebula itself comes from the Latin word nebula, which means cloud. In fact, it is a dust and gas cloud that provides ideal conditions for star birth or death. These celestial wonders are illuminated by internal or nearby stars.
Nebula’s contain amazing clusters of stars, dust and gas, which often affect their shape. Of course, you need a good telescope to get high-quality images. The color palette appears only on long exposures, showing hydrogen (pink), helium (blue), nitrogen (red) and oxygen (blue-green).
But the nebula can be dark. This view was discovered by William Herschel, presenting dust and gas clouds, devoid of illumination of the stars, and too dense to pass the light.
5 Nebula Types
1. Emission nebula
The emission lines and the emission nebula create their own luminosity. Hydrogen atoms come into activity because of the powerful ultraviolet light of stars. Then hydrogen is ionized (it loses the electron emitting the photon).
O-type stars can ionize gas within a radius of 350 light years. The M17 nebula discovered de Chezau in 1746, and in 1764 Charles Messier reopened it. It is located in Sagittarius and is also called the Swan, Omega, Horseshoe and Lobster nebula. Incredibly bright and its pink glow can be seen without the use of technology in low latitudes (visible value – 6). Inside are the young stars creating the HII area. Ionized hydrogen is responsible for the red color.
Infrared light helps to find a huge amount of dust hinting at active star formation. Inside there is a cluster of 30 stars, shaded by a nebula, rubbed in a diameter of 40 light years. The total mass of 800 times the sun.
M17 removed by 5500 light years. Together with the M16 is located in the same spiral arm of the Milky Way (Sagittarius-Carina).
2. Reflection Nebula
This type of nebula is filled with hydrogen (the most common element in the universe) and dust. It reflects the light, sending it to the stars it contains. This effect can be traced to the Pleiades blue nebula.
Emission emissions are often mixed with reflective nebulae. An example is M42 (Orion Nebula). A glowing gas surrounds young stars located on the edge of a giant molecular cloud that is 1,500 light-years distant from us.
In the center, four blue stars are visible, forming a trapezium and illuminating the substance in space. Atoms absorb starlight and forward in their own color. Radio astronomy studies show that the Orion Nebula is part of the large and opaque Orion cloud. Cloud compression appeared in trapezoid stars and a group of protostar nebulae that are located behind the Orion Nebula. This is the nearest star formation area.
3. ark nebula
A dark nebula is a cloud filled with dust and cold gas that does not let in visible light, which closes visibility to the inner stars. The average dust diameter is 1 micron (0.001 mm). This is the density of cigarette smoke. Small particles collect a small amount of molecules.
4. Planetary nebula
If diffuse (reflection and emission) nebulae are associated with the appearance of stars, then planetary nebulae are their remnants. The name planetary is taken from the first observations of objects with a circular aspect. At the time of completion, the star begins to emit strong ultraviolet flares. The light illuminates the extruded gas, and we see a planetary nebula. Hydrogen appears in red light, and oxygen – green.
The Snail Nebula attracts amateur astronomers due to its bright colors and resemblance to a huge eye. It was found in the 18th century and removed 650 light years (the constellation Aquarius).
5. Supernova remnant Nebulae
Supernova remnants form when a star completes life in a massive explosion known as a supernova. The explosion carries a large amount of star matter into space. This cloud of matter is ablaze with the remnants of the star that produced them. One of the best examples of a supernova remnant is the Crab Nebula (M1) in the constellation Taurus. It is illuminated by a pulsar, which was formed by a supernova.
Nebula formation
Nebula appears when ISM particles undergo gravitational collapse. Due to the mutual gravitational influence, the matter approaches and creates areas with greater density. Stars can form in the center, whose ultraviolet ionizing radiation causes the surrounding gas to become visible at optical wavelengths.
Most of the nebulae are large, and their diameter reaches hundreds of light years. They are denser than the surrounding space, but they are inferior to the vacuum created in the terrestrial environment. If a nebula resembling Earth existed, then its mass would reach a couple kilograms.
History of observations
In ancient times, people noticed a lot of astronomical objects. The first recorded observation of the nebula occurred in 150 AD. At that time, Ptolemy found 5 stars. In his book Almagest, he also noted the bright areas between Ursa Major and Leo, who were not tied up by any observable star.
The Persian astronomer Abd al-Rahman al-Sufi first recorded the nebula in the Book of Fixed Stars (964 AD). He talked about the cloud, where Andromeda is now located. In addition, he recorded the Omicron of Sails and the Brohci Cluster.
On July 4, 1054, a supernova broke out that created the Crab Nebula (SN 1054). Chinese and Arab astronomers were able to see it and register. There were testimonies that many civilizations noticed all these objects, but did not leave records behind them.
In the 17th century, observations became even more accessible due to the appearance of telescopes. It all began in 1610, when the first astronomer Nebula was registered by the astronomer Nicolas-Claude Fabry de Peyresc from France In 1618 an astronomer from Switzerland, Johann Baptist Zizat, also saw her, after which Christian Huygens joined in 1659.
By the 18th century, the number of nebulae found began to increase, and astronomers realized that it was time to create lists. In 1715, Edmund Halley published a list of Messier Nebulae 11, Messier 13, Messier 22, Messier 31, Messier 42, and the Omega Centaurius globular cluster (NGC 5139).
In 1746, Jean Philippe de Cheesau provided 20 nebulae, including 8 new ones. Nicolas Louis de Lackaille (in 1751-1753) categorized 42 nebulae, most of which had not been mentioned before. And in 1781, the well-known catalog of Charles Messier (101 objects) appeared, which also included galaxies and comets.
The number of nebulae greatly replenished William Herschel and his sister Caroline. In 1786, their publication “A Thousand New Nebulae and Star Clusters” was published, which were supplemented with the second and third catalog in 1786 and 1802. Then Herschel believed that the nebula is an unresolved cluster of stars, and he would change his mind if in 1790 he saw the nebula surrounding a distant star.
From 1864, William Huggins began to divide nebulae based on their spectra. 1/3 had a gas emission spectrum (emission), while others demonstrated a continuous spectrum consistent with the stellar mass (planetary).
Vesto Slyfer in 1912 added reflective nebulae after seeing the Pleiades cluster. After the debate in 1922, it became clear that many of the objects observed earlier were not nebulae, but distant spiral galaxies. At the same time, Edwin Hubble announced that almost all the nebulae are associated with the stars that provide lighting. Since then, the number has grown, and the classification has become more clear.
It turns out that the nebula is not only the start for the star, but also the finish. And in all star systems there will be foggy clouds and masses awaiting the birth of a new star generation. On our website, you can not only admire nebulae photos and explore the entire list, but also view them online using 3D models that list all the stars, nebulae, constellations and clusters both inside and outside the Milky Way galaxy.
Nebula cloud in detail
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