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This nebula is in the western part [4] of the Perseus molecular cloud and is a young region of very active star formation, [6] being one of the best-studied objects of its type. [4] It contains a fairly typical hierarchy of star clusters that are still embedded in the molecular cloud in which they formed, [ 7 ] which are split into two main sub ...
The cores range in mass from a fraction to several times that of the Sun and are called protostellar (protosolar) nebulae. [2] They possess diameters of 0.01–0.1 pc (2,000–20,000 AU) and a particle number density of roughly 10,000 to 100,000 cm −3. [a] [35] [37] The initial collapse of a solar-mass protostellar nebula takes around 100,000 ...
This is a list of diffuse nebulae. Most nebulae are diffuse , meaning that they do not have well-defined boundaries. Types of diffuse nebulae include emission nebulae and reflection nebulae .
List of the largest nebulae Image Nebula Maximum dimension (in light-years/parsecs) Type Notes NGC 262 Halo Cloud 1,300,000 ly (400,000 pc) [1] H I region: Spiral nebula surrounding NGC 262, which is one of the largest known galaxies. Leo Ring: 650,000 ly (200,000 pc) [2] HVC: A large ring of cold gas that formed from a collision of two ...
The "Great Spiral Nebula" in the constellation Andromeda (1902 photograph). The Debate was over whether this was a cloud of gas and dust or a distant galaxy. Shapley presented the case that the Milky Way is the entirety of the Universe. [2] He argued that "spiral nebulae" such as Andromeda were simply part of the Milky Way
Reflection nebula are usually blue because the scattering is more efficient for blue light than red (this is the same scattering process that gives us blue skies and red sunsets). Reflection nebulae and emission nebulae are often seen together and are sometimes both referred to as diffuse nebulae. Some 500 reflection nebulae are known.
Planetary nebulae, represented here by the Ring Nebula, are examples of emission nebulae. An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star .
In 1755, Immanuel Kant speculated that observed nebulae could be regions of star and planet formation. In 1796, Laplace elaborated by arguing that the nebula collapsed into a star, and, as it did so, the remaining material gradually spun outward into a flat disc, which then formed planets. [8]