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  2. Nebula - Wikipedia

    en.wikipedia.org/wiki/Nebula

    The compact object that was created after the explosion lies in the center of the Crab Nebula and its core is now a neutron star. Still other nebulae form as planetary nebulae . This is the final stage of a low-mass star's life, like Earth's Sun. Stars with a mass up to 8–10 solar masses evolve into red giants and slowly lose their outer ...

  3. Planetary nebula - Wikipedia

    en.wikipedia.org/wiki/Planetary_nebula

    Planetary nebulae probably play a crucial role in the chemical evolution of the Milky Way by expelling elements into the interstellar medium from stars where those elements were created. Planetary nebulae are observed in more distant galaxies, yielding useful information about their chemical abundances.

  4. Nebular hypothesis - Wikipedia

    en.wikipedia.org/wiki/Nebular_hypothesis

    The amount of gas a super-Earth that formed in situ acquires may depend on when the planetary embryos merged due to giant impacts relative to the dissipation of the gas disk. If the mergers happen after the gas disk dissipates terrestrial planets can form, if in a transition disk a super-Earth with a gas envelope containing a few percent of its ...

  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. Star formation - Wikipedia

    en.wikipedia.org/wiki/Star_formation

    The nebula nearest to the Sun where massive stars are being formed is the Orion Nebula, 1,300 light-years (1.2 × 10 16 km) away. [11] However, lower mass star formation is occurring about 400–450 light-years distant in the ρ Ophiuchi cloud complex. [12]

  7. Stellar evolution - Wikipedia

    en.wikipedia.org/wiki/Stellar_evolution

    All stars are formed from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star. Nuclear fusion powers a star for most of its existence.

  8. Formation and evolution of the Solar System - Wikipedia

    en.wikipedia.org/wiki/Formation_and_evolution_of...

    The various planets are thought to have formed from the solar nebula, the disc-shaped cloud of gas and dust left over from the Sun's formation. [36] The currently accepted method by which the planets formed is accretion , in which the planets began as dust grains in orbit around the central protostar.

  9. Orion Nebula - Wikipedia

    en.wikipedia.org/wiki/Orion_nebula

    The nebula has revealed much about the process of how stars and planetary systems are formed from collapsing clouds of gas and dust. Astronomers have directly observed protoplanetary disks and brown dwarfs within the nebula, intense and turbulent motions of the gas, and the photo-ionizing effects of massive nearby stars in the nebula.