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  2. Nebula - Wikipedia

    en.wikipedia.org/wiki/Nebula

    Similar nebulae not illuminated by stars do not exhibit visible radiation, but may be detected as opaque clouds blocking light from luminous objects behind them; they are called dark nebulae. [ 25 ] Although these nebulae have different visibility at optical wavelengths, they are all bright sources of infrared emission, chiefly from dust within ...

  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. Nebular hypothesis - Wikipedia

    en.wikipedia.org/wiki/Nebular_hypothesis

    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 ...

  5. 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 .

  6. Interstellar cloud - Wikipedia

    en.wikipedia.org/wiki/Interstellar_cloud

    Reflection nebula IRAS 10082-5647 observed by the Hubble Space Telescope. These interstellar clouds possess a velocity higher than can be explained by the rotation of the Milky Way. [5] By definition, these clouds must have a v lsr greater than 90 km s −1, where v lsr is the local standard rest velocity.

  7. Bok globule - Wikipedia

    en.wikipedia.org/wiki/Bok_globule

    In astronomy, Bok globules are isolated and relatively small dark nebulae containing dense cosmic dust and gas from which star formation may take place. Bok globules are found within H II regions, and typically have a mass of about two [1] to 50 solar masses contained within a region about a light year or so across (about 4.5 × 10 47 m 3). [2]

  8. Evaporating gaseous globule - Wikipedia

    en.wikipedia.org/wiki/Evaporating_gaseous_globule

    Evaporating gas globules were first conclusively identified via photographs of the Pillars of Creation in the Eagle Nebula taken by the Hubble Space Telescope in 1995. [2] [3] EGG's are the likely predecessors of new protostars. Inside an EGG the gas and dust are denser than in the surrounding dust cloud.

  9. Molecular cloud - Wikipedia

    en.wikipedia.org/wiki/Molecular_cloud

    The Finger of God Globule has broken off from the Carina Nebula. Newly formed stars are visible nearby, their images reddened by blue light being preferentially scattered by the pervasive dust. This image spans about two light-years and was taken by the Hubble Space Telescope in 1999. Part of the Taurus molecular cloud [17]