Planetary nebulae (PNe) are believed to form when the envelope of gas and dust, ejected at the end of the AGB phase of stellar evolution, is heated by the hot stellar nucleus, left after mass loss due to the "superwind" is terminated. The presence of residual molecular gas in PNe ...
For the more massive asymptotic giant branch stars that form planetary nebulae, whose progenitors exceed about 3M⊙, their cores will continue to contract. When temperatures reach about 100 million K, the available helium nuclei fuse into carbon and oxygen, so that the star again resumes radiating...
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Planetary nebulae (PNe) are expanding shells of gas and dust that have been ejected from a star during the process of its evolution from a main sequence star into a red giant or white dwarf. They are relatively rare, but are important for astronomers studying the chemical evolution of stars ...
They wanted to find out why these stellar leftovers (planetary nebulae) sometimes didn't form rings, but strange shapes. One of the objects they studied was the cloud in this picture. 发现这对巨大恒星的天文团队实际上打算解决一个很难的问题,他们想知道为什么有时这些恒星的残余物不是环形的,而是...
[1] Despite their name, planetary nebulae have nothing to do with planets. This misnomer originates from the round, planet-like appearance of these objects when viewed through early telescopes. As telescopes improved, the striking beauty and stellar origin of planetary nebulae became more obvious,...
Planetary Nebulae Merged Ionization/Dissociation Fronts hydrogen ionization and dissociation front around an ultraviolet radiation source should merge when the ratio of ionizing photon flux to gas density is sufficiently low and the spectrum is sufficientl 引用走势 2011 被引量:5 0...
In the few past years, polarimetric observations with the VLT have led to the discovery of magnetic fields in a large number of stellar objects in late evolutionary stages. In addition to improving our understanding of these beautiful planetary nebulae form, the detection of these magnetic fields ...
As stars evolve and turn into red giants, asymptotic giant branch stars, and planetary nebulae they engulf the inner planets, evaporating or partially evaporating them depending on how massive they are. As the star loses mass, planets that are not engulfed move further out from the star. ...
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