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  2. Nebula - Wikipedia

    en.wikipedia.org/wiki/Nebula

    A protoplanetary nebula or preplanetary nebula [27] (PPN, plural PPNe) is an astronomical object which is at the short-lived episode during a star's rapid evolution between the late asymptotic giant branch (LAGB) phase and the subsequent planetary nebula (PN) phase.

  3. Planetary nebula - Wikipedia

    en.wikipedia.org/wiki/Planetary_nebula

    NGC 6326, a planetary nebula with glowing wisps of outpouring gas that are lit up by a binary [3] central star. A planetary nebula is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives. [4] The term "planetary nebula" is a misnomer because they are unrelated to ...

  4. Emission nebula - Wikipedia

    en.wikipedia.org/wiki/Emission_nebula

    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 .

  5. Eagle Nebula - Wikipedia

    en.wikipedia.org/wiki/Eagle_Nebula

    The Eagle Nebula is part of a diffuse emission nebula, or H II region, which is catalogued as IC 4703. This region of active current star formation is about 5700 light-years distant. A spire of gas that can be seen coming off the nebula in the northeastern part is approximately 9.5 light-years or about 90 trillion kilometers long. [6]

  6. Dark nebula - Wikipedia

    en.wikipedia.org/wiki/Dark_nebula

    A dark nebula or absorption nebula is a type of interstellar cloud, particularly molecular clouds, that is so dense that it obscures the visible wavelengths of light from objects behind it, such as background stars and emission or reflection nebulae.

  7. New General Catalogue - Wikipedia

    en.wikipedia.org/wiki/New_General_Catalogue

    The New General Catalogue of Nebulae and Clusters of Stars (abbreviated NGC) is an astronomical catalogue of deep-sky objects compiled by John Louis Emil Dreyer in 1888. The NGC contains 7,840 objects, including galaxies , star clusters and emission nebulae .

  8. Crab Nebula - Wikipedia

    en.wikipedia.org/wiki/Crab_Nebula

    The nebula is seen in the visible spectrum at 550 nm (green light). The Crab Nebula was the first astronomical object recognized as being connected to a supernova explosion. [13] In the early twentieth century, the analysis of early photographs of the nebula taken several years apart revealed that it was expanding. Tracing the expansion back ...

  9. Bipolar nebula - Wikipedia

    en.wikipedia.org/wiki/Bipolar_nebula

    A bipolar nebula is a type of nebula characterized by two lobes either side of a central star. About 10-20% of planetary nebulae are bipolar. [2] Formation