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A type of naturally occurring physical entity, association, or structure that exists within the observable universe but is a more complex, less cohesively bound structure than an astronomical body, consisting perhaps of multiple bodies or even other objects with substructures, such as a planetary system, star cluster, nebula, or galaxy. Though ...
A protoplanetary nebula or preplanetary nebula [1] (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. A PPN emits strongly in infrared radiation, and is a kind of reflection nebula.
The Bubble Nebula (NGC 7635), imaged by the Hubble Space Telescope, is seven light years across. A stellar-wind bubble is a cavity light-years across filled with hot gas blown into the interstellar medium by the high-velocity (several thousand km/s) stellar wind from a single massive star of type O or B.
The Carina Nebula is an example of a diffuse nebula Most nebulae can be described as diffuse nebulae, which means that they are extended and contain no well-defined boundaries. [ 24 ] Diffuse nebulae can be divided into emission nebulae , reflection nebulae and dark nebulae .
It is the earliest phase in the process of stellar evolution. [1] For a low-mass star (i.e. that of the Sun or lower), it lasts about 500,000 years. [ 2 ] The phase begins when a molecular cloud fragment first collapses under the force of self-gravity and an opaque, pressure-supported core forms inside the collapsing fragment.
A molecular cloud—sometimes called a stellar nursery if star formation is occurring within—is a type of interstellar cloud of which the density and size permit absorption nebulae, the formation of molecules (most commonly molecular hydrogen, H 2), and the formation of H II regions.
Contains massive stars that have strong stellar winds. Ring Nebula (NGC 6822) 838 ly (257 pc) H II region: The Ring Nebula is located in the lower right of the image Gum Nebula: 809–950 ly (248–291 pc) [16] [17] Emission nebula: Extends about 36° of the sky Bubble Nebula (NGC 6822) 758 ly (232 pc) [18] [19] [20] H II region
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 ...