Hot Crescent Nebula

Contemplation of the object ngc 6888, measuring about 25 x 18 light-years is equivalent to look at the past 4,700 years, the past, representing a nebula, which supplies the "fuel" and it stirs up the glow blue star, located in center of the nebula. And not just some blue star, a star – supergiant, with a large mass, which consumes its fuel at 'full speed'. In addition, it was not just a star-supergiant, but also a hot star belonging to the class of stars 'Wolf – Rayet (Wolf Rayet)' (HD 192163). Now, after just a couple of million years, 'Star Gas' is almost used up and the stars came a period of significant change: it goes into the category of candidates for supernovae. Here, look, the star, which spews out its outer layers into space with frightening speed! 'Snapshots are used to restrict the models of the ionization structure of the crust with nebular features', – says Brian D. Moore (Brian D. Read more from to gain a more clear picture of the situation.

Moore (and others) from the University of Arizona, Department of Physics and Astronomy. "Based on these models, we speculated what physical conditions must be maintained in the framework of these features, and figure out what elements could conceivably be present inside the nebula. The results of our analysis, given the small level of heterogeneity which is found in the photographs, cast doubt on the assumption underlying the traditional methodologies of data interpretation nebular spectroscopy. "Thermal" pressure masses higher than the estimated internal pressure of the stellar wind shock, which means that current conditions have changed significantly in less than a few thousand years. " While the central star undergoes a significant loss of mass, gas accumulates a lot of oxygen and hydrogen directly in front of separate big 'explosion' star WR-class, creating 'hot bubble', whose structure can not be fully explained until now. 'A detailed analysis of the distribution of hi at low positive rates allowed us to identify two various structures, most likely associated with the star and the ring nebula. They are (in the direction from the inner regions to outer): (1) elliptical shell having the dimensions 11.8 6.3 (in parsecs), which covers Ring Nebula (marked with the inner shell), and (2) a distorted ring hi, diameter of 28 pc (parsecs), is also found in the ir – emission (outer shell).

The boundaries of the inner shell striking manner are the most bright areas of ngc 6888, showing areas where there is an interaction with the surrounding nebula gas. The third structure, exterior feature is a broken arc, we find a slightly higher speeds than the above-mentioned shell '- says Christina Kapp (Christina Cappa) (and others),' We propose a scenario in which a strong stellar wind of hd 192163, which propagates in an inhomogeneous interstellar medium, the outer shell blew over phases of the main sequence star's life. Subsequently, from the material ejected by the star in the phase lbv (bright blue variables (star)) (or rsg (red supergiant)) and wr (Wolf-Rayet star), formed the nebula ngc 6888. This material collided with the farthest inner wall of the outer shell, giving rise to the inner shell. Unclear relationship with the external characteristics of stars and nebulae. "

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