The nature of spiral galaxies, is not yet fully understood. There are currently two types of theories that may explain this structure according to the environment of the Galaxy. But new research suggests that one of these theories can be largely incorrect. For galaxies with nearby companions, astronomers have suggested that the gravitational forces may cause the spiral structure. However, in isolated galaxies, is necessary another mechanism for galaxies to form these structures without the intervention of a neighbour. A possible solution to this was studied for the first time in 1964 by Lin Shu and it emerged that such a structure is not more than a hope. Instead, these spiral arms were not structures in motion, but the areas of greater density that remain stationary, as stars going in and out of them similar to a bottleneck in the transit, stays in place, even though the cars are traveling inside and outside. This theory has been called Theory of the density of Lin Shu of the waves and has been a great success. Previous studies have reported a progression of cold regions HI, and dust in the inner portion of the spiral arms, colliding in the region of higher density and so causes the formation of stars, making out hot star class or class B who die before leaving the structure, leaving the lower-mass stars to fill the rest of the Galactic disk. A question to this theory is, longevity of the super-densa region. According to Lin Shu, as well as many other astronomers, these structures are generally stable over long periods of time. Others suggest that the density of the wave comes and goes in a relatively short life in recurring patterns. The galaxies pattern is composed of orbitals of the individual stars, that periodically are aligned to create the spiral arms. New research analyzed the progression of the star formation in as gas and dust came into the region of shock produced by the wave of density-Lin Shu. If the theory were correct, is expected find a progression in which for the first time are the cool HI gas and carbon monoxide, and compensation from hot molecular hydrogen and the 24 microns of emission of the stars that formed in the clouds and, finally, movement of the UV issuance of fully formed and not darkened stars. We examined 12 spiral galaxies nearby, M51, M63 and M66, M74, M81 and M95. These galaxies represent variations of the grand design spiral galaxies, spiral barradas, flocculants spirals, and a spiral interacting. When a computer algorithm was used to examine each of the compensation that supporting the theory of Lin Shu, was informed that not be could find a difference in location between the 3 different stages of star formation. This contradicts previous studies (which were made to eye and therefore subject to possible errors), and casts doubt on the long life of the spiral structure as it predicts the theory of Lin Shu. On the other hand, this result is in accordance with the possibility that transient spiral arms to break and reform in a manner periodic. Another option that rescues of the density wave theory is that speed patterns, there are multiple waves of density in a manner more complex and thus blurs the expected displacement. This possibility is supported by a 2009 study that assigns these speeds and found that several spiral galaxies are likely to have such behavior. The technique itself can be erroneous and underestimates the issuance of each zone of star formation. To resolve the issue, are needed to produce models more refined and explore the regions with greater detail and more galaxies... (Translated by Bing)
Posted on: Sat, 23 Aug 2014 23:40:22 +0000
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