Fundamental Reasons for the Similarity and Differences of the Mass Spectra of Various Astronomical Objects
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FUNDAMENTAL REASONS FOR THE SIMILARITY AND DIFFERENCES OF THE MASS SPECTRA OF VARIOUS ASTRONOMICAL OBJECTS
A. V. Tutukov and B. M. Shustov
The mass spectra of astronomical objects of various kinds are compared: cosmic dust, asteroids, planets, stars, star clusters, galaxies, and galactic clusters. The authors have previously noted a similarity in the (initial) mass functions for relatively massive objects (stars, galaxies, galactic clusters). In this paper the range of masses of astronomical objects is extended to the limit and covers roughly 68 orders of magnitude. It is confirmed that the initial mass spectra of objects in ensembles formed by fragmentation (a fast process) may, in a first approximation in a statistically significant range be represented by a basis (reference) function dN / dM v M 2 , where dN is the number of objects in a range [M, M+dM] of masses. The significance of this function is the probability density of formation of objects, which total mass in a range [d ln M] of masses is independent of the mass M or, in other words, reduces to the absence of a distinct mass scale. The physical reasons determining the deviation of the initial mass functions from the reference function are discussed briefly. It is noted that the mass spectra in ensembles of objects formed by mergers (coagulation in the case of dust), i.e., in a relatively slow evolutionary process, can also be of a form close a reference function. The main reason for this universality lies in the random character of the processes of formation and evolution of these ensembles of astronomical objects. Keywords: mass spectrum: initial mass function
Institute of Astronomy, Russian Academy of Sciences, Moscow, Russia; e-mail: [email protected]; [email protected]
Original article submitted June 29, 2020. Translated from Astrofizika, Vol. 63, No. 4, pp. 631-647 (November 2020) 552
0571-7256/19/6304-0552 ©2020 Springer Science+Business Media, LLC
1. Introduction
Mass is one of the fundamental characteristics of astronomical objects: asteroids, planets, stars, galaxies, etc. In astronomical ensembles (sets of objects of a single type), where the number of objects is very large, statistical methods may be applicable. Statistical distributions are extremely informative and reflect the fundamental features of the formation and evolution of the objects. This applies perhaps first of all to the mass distribution of objects. Statistical distributions change with time, since all the objects on the scales discussed here are born, evolve, and, ultimately, cease to exist. Thus, any ongoing distribution with respect to masses (note that most often we observe, not the initial distribution, but indeed an ongoing one) is the result of the the creation of the objects (i.e., an initial distribution), as well as of the evolutionary processes acting over an extended time from their birth to the present time. If the evolutionary processes in an ensemble have gone on for a long time, i.e., on a scale ta much longer than the characteristic time te determinin
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