Deep space objects > Nebula
The word nebula itself comes from the Latin “nebula”, which means “cloud.” Essentially, it is a dust and gas cloud that provides ideal conditions for stellar birth or death. These celestial wonders are illuminated by the inner or neighboring stars.
Nebulae contain amazing clusters of stars, dust, and gas that often affect their shape. Of course, you need a good telescope to get good quality images. The color palette appears only at long exposures, showing hydrogen (pink), helium (blue), nitrogen (red) and oxygen (blue-green).
But the nebula can also be dark. This view was discovered by William Herschel, presenting dust and gas clouds devoid of starlight and too dense to let light through.
Types of nebula
The emission line nebula and the emission nebula create their own glow. Hydrogen atoms come into activity due to the powerful ultraviolet light from the stars. Then the hydrogen is ionized (it loses an electron emitting a photon).
Type O stars can ionize gas within a radius of 350 light years. The M17 nebula was discovered by de Chezot in 1746 and rediscovered by Charles Messier in 1764. 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 (apparent magnitude – 6). Inside are young stars creating the HII region. Ionized hydrogen is responsible for the red color.
Infrared light helps find massive amounts of dust, hinting at active star formation. Inside is a cluster of 30 stars, shadowed by a nebula that sweeps across 40 light-years across. The total mass is 800 times that of the sun.
M17 is 5,500 light years distant. Together with M16, it is located in one spiral arm of the Milky Way (Sagittarius-Carinae).
The most famous emission nebulae
Messier emission nebulae
This type of nebula is filled with hydrogen (the most abundant element in the universe) and dust. It reflects light, sending it to the stars it contains. This effect can be seen in the blue Pleiades nebula.
Emission nebulae are often mixed with reflection nebulae. An example is M42 (Orion Nebula). The glowing gas surrounds young stars at the edge of a giant molecular cloud 1,500 light-years away.
In the center, 4 blue stars are visible, forming a trapezoid and illuminating matter in space. Atoms absorb starlight and transport it in their own color. Radio astronomy studies show that the Orion Nebula is part of the large, opaque Orion cloud. Cloud compression has appeared in trapezoidal stars and a group of protostellar nebulae that lie behind the Orion Nebula. This is the closest star-forming region to us.
The most famous reflection nebulae
A dark nebula is a cloud filled with dust and cold gas that does not allow visible light to pass through, which obscures 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 number of molecules.
The most famous dark nebulae
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 end of its existence, the star begins to emit strong ultraviolet flares. Light illuminates the displaced gas and we see a planetary nebula. Hydrogen appears in red light and oxygen in green.
The Helix Nebula attracts amateur astronomers due to its vibrant colors and its resemblance to a huge eye. It was found in the 18th century and is 650 light years distant (constellation Aquarius).
The most famous planetary nebulae
Messier planetary nebulae
Supernova remnant nebula
Supernova remnants form when a star ends its life in a massive explosion known as a supernova. The explosion carries away a large amount of the star’s material into space. This cloud of matter glows with the remnants of the star that gave birth to 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 that was formed by a supernova.
The most famous nebulae supernova remnants
List of lesser known nebulae:
- Witch Head
- Cat paw
- Butterfly wings
- Flaming star nebula
- Bubble Nebula
- Rotten Egg Nebula
- Phantom stroke nebula
- Thor’s Helmet Nebula
The nebula appears when ISM particles undergo gravitational collapse. Due to the mutual gravitational influence, matter approaches and creates areas of higher density. At the center, stars can form, whose ultraviolet ionizing radiation makes the surrounding gas appear at optical wavelengths.
Most nebulae are large, and their diameter reaches hundreds of light years. They are denser than the surrounding space, but are inferior to the vacuum created in the earthly environment. If there was a nebula similar to the Earth, then its mass would reach a couple of kilograms.
History of observation of nebulae
In ancient times, people noticed a lot of astronomical objects. The first recorded sighting of the nebula was in AD 150. At that time, Ptolemy discovered 5 stars. In his book Almagest, he also noted bright areas between the Big Dipper and Leo, which were not associated with any observed star.
The Persian astronomer Abd al-Rahman al-Sufi recorded the nebula for the first time in the Book of Fixed Stars (AD 964). He talked about the cloud where Andromeda is now. He also recorded the Omicron of the Sails and the Brohchi Cluster.
On July 4, 1054, a supernova erupted, creating the Crab Nebula (SN 1054). Chinese and Arab astronomers were able to see it and register it. There was evidence that many civilizations noticed all of these objects, but left no records behind them.
In the 17th century, observations became even more accessible with the advent of telescopes. It all began in 1610, when French astronomer Nicola-Claude Fabri de Peyresque first registered the Orion Nebula. In 1618, the astronomer from Switzerland Johann Baptist Cisat also saw it, after which Christian Huygens joined in 1659.
By the 18th century, the number of nebulae found began to increase, and astronomers realized it was time to create lists. In 1715, Edmund Halley published a list of the nebulae Messier 11, Messier 13, Messier 22, Messier 31, Messier 42, and the Omega Centauri globular cluster (NGC 5139).
In 1746, Jean Philippe de Chezot provided 20 nebulae, including 8 new ones. Nicolas Louis de Lacaille (1751-1753) categorized 42 nebulae, most of which have never been mentioned before. And already in 1781, the famous Charles Messier catalog (101 objects) appeared, which also included galaxies and comets.
William Herschel and his sister Caroline added significantly to the number of nebulae. In 1786, their publication “A Thousand New Nebulae and Star Clusters” was published, which were supplemented by the second and third catalogs in 1786 and 1802. Then Herschel believed that the nebula was an unresolved cluster of stars and he would change his mind if in 1790 he saw a nebula surrounding a distant star.
From 1864, William Huggins began to separate nebulae based on their spectra. 1/3 had a spectrum of gas emission (emission), while others showed a continuous spectrum consistent with stellar mass (planetary).
Vesto Slipher added reflection nebulae in 1912 after seeing the Pleiades cluster. After a debate in 1922, it became clear that many of the objects previously observed were not nebulae, but distant spiral galaxies. At the same time, Edwin Hubble announced that almost all nebulae are associated with stars that provide illumination. Since then, the number has grown and the classification has become clearer.
It turns out that the nebula is not only a start for a star, but also a finish. And in all stellar systems there will be foggy clouds and masses awaiting the birth of a new stellar generation. On our site you can not only admire the photos of nebulae and explore the entire list, but also view them online using 3D models, which indicate all the stars, nebulae, constellations and clusters both in the Milky Way galaxy and beyond. …