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Other nebulae form as the result of supernova explosions; the death throes of massive, short-lived stars. The materials thrown off from the supernova explosion are then ionized by the energy and the compact object that its core produces. One of the best examples of this is the Crab Nebula, in Taurus.
The working model to explain this hypothesizes that this PN is composed of a giant companion that caused a central dense gas region to form, and a white dwarf that provides ionizing photons for the PN. [5] Mz 3 is often referred to as the Ant Nebula because it resembles the head and thorax of a garden-variety ant.
The heating of the disk is primarily caused by the viscous dissipation of turbulence in it and by the infall of the gas from the nebula. [39] [40] The high temperature in the inner disk causes most of the volatile material—water, organics, and some rocks—to evaporate, leaving only the most refractory elements like iron. The ice can survive ...
Pierre-Simon Laplace, one of the originators of the nebular hypothesis. Ideas concerning the origin and fate of the world date from the earliest known writings; however, for almost all of that time, there was no attempt to link such theories to the existence of a "Solar System", simply because it was not generally thought that the Solar System, in the sense we now understand it, existed.
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 .
Representative lifetimes of stars as a function of their masses The change in size with time of a Sun-like star Artist's depiction of the life cycle of a Sun-like star, starting as a main-sequence star at lower left then expanding through the subgiant and giant phases, until its outer envelope is expelled to form a planetary nebula at upper right Chart of stellar evolution
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.