For the first time in the world, scientists have used network theory methods to solve astronomical problems – explain the initial mass function, a correlation between the number of small and big stars in galaxies and other stellar systems. The work of researchers published in the latest issue of The Astrophysical Journal
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Andrew Klishin (post-graduate student at the University of Michigan) under the direction of Igor Chilingaryan (Harvard-Smithsonian center for astrophysics, State astronomical Institute of the Sternberg) first applied the methods of random network theory (network science) to solve astronomical problems, over which scientists have fought 60 years – an explanation form the initial mass function of stars
«Similar methods have been used in various fields of science – sociology and computer science to molecular biology, but never in astrophysics.” , – says Igor Chilingaryan
the initial mass function of stars -. a feature that shows what proportion of the total number of stars in the stellar system make stars of the mass (ie, the ratio of large and small stars in galaxies). The law of distribution of the initial mass of stars was derived empirically theoretical physicist and astrophysicist Edwin Salpeter in 1955 (the law was called “Salpeter mass function”). Salpeter first identified the initial mass function of stars in the solar neighborhood. Derived them the law states that the distribution of stars with a mass more than one solar described by a power law with an exponent of -2.35, ie, stars with masses ten solar meet about 10 2,35 = 220 times less than stars like the sun.
Knowing how the stars in the star system allocated to the masses, for astronomers it is very important. Star system can be compared to a large family, all of whose members are constantly interacting with each other: they are in a certain way share the living space, and if you are experiencing any external influence, then obey him according to the same laws. In order to better understand how the members of this “family” influence each other,
astronomers important to know which stars are a member of this “family”, that is to have data how many stars a mass present in the star system.
Scientists presented absorbs gas from the diffuse interstellar medium system of dense clouds, from which stars are formed as a spatial network that grows at the following the principle of a preferred connection: the more links a node, the more it creates new connections. In the case of a cloud of interstellar communication media – is the gravitational forces that act between the dense molecular clouds from which then formed the stars
«Instead of describing the process of growth of each individual protostars, we presented the entire system as a spatial network. which grows on the basis of the preferred connection, and used mathematical methods of network theory. We have shown that the power law, which governs the form of the initial mass function, is formed regardless of the initial distribution of the mass protostars, provided that in the cloud of interstellar medium density distribution of the fractal that follows directly from the turbulence theory, developed by well-known Soviet mathematician Andrey Kolmogorov. With objects that have self-similar fractal distribution or density, people meet on a daily basis. These objects include clouds in the Earth’s atmosphere, snowflakes, and even some fruits and vegetables, such as cauliflower and broccoli “, – says Igor Chilingaryan.
Thus, the scientists were able to with the help of eight equations and without the involvement of non-physical basis of additional parameters theoretically explain the shape of the initial mass function of stars.
Chilingaryan According to Igor, before this was done only in the framework of the “classic astrophysical methods” – in large series of articles on dozens of pages of complex calculations in hundreds of equations
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« Igor asked me to work on this project after our chance meeting in Boston, where I mentioned my interest in statistical physics, – says Andrey Klishin. – This area of physics explores aspects of a large number of particle systems, which do not depend on the small details. Thus, one and the same exponent in the Salpeter -2.35 been measured in a large number of star clusters of different age, metallicity and the total weight. Hence, this value is not due to local parts of a particular cluster, and some more general mechanisms. That is why we propose the principle of preferential attachment in the article, we quote the work on network theory, bibliometrics, the emergence of species:. In all these tasks the statistical properties very similar to each other »
The theory of random networks – is a science actively developing during the last 15-20 years. As its name implies, it is engaged in the study of the properties of both networks mathematical objects, regardless of what the actual system is understood as a network. So, the theory of networks, you can use
for description of the electrical network as a set of substations and transmission lines, the interaction of multiple proteins within a living cell in the body, relationships between users in a social network such as Facebook or even all over the internet and to communicate in scientific collaborations
«This paper -. The first of its kind, and it provides the basis for a new interdisciplinary aspects in astrophysics. In the future, we plan to develop a family of methods and use them to solve a whole range of astrophysical problems in the study of the mechanisms of star and in observational cosmology (the study of large-scale structure of the distribution of matter in the universe), “- concludes Igor Chilingaryan.
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