Formation of Stellar Streams Due to the Decay of Star Clusters, OB Associations, and Galaxy Satellites
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ation of Stellar Streams Due to the Decay of Star Clusters, OB Associations, and Galaxy Satellites A. V. Tutukova, M. D. Sizovaa, *, and S. V. Vereshchagina a Institute
of Astronomy, Russian Academy of Sciences, Moscow, 119017 Russia *e-mail: [email protected]
Received May 8, 2020; revised May 18, 2020; accepted May 30, 2020
Abstract—This paper presents a scenario of the evolution of OB associations and star clusters from formation to decay, in the process of which they turn into stellar streams moving in the disk and stellar “rings” around the galactic center. The scenario also includes the formation of stellar streams by galaxies absorbing their dwarf satellite galaxies. The simplest spatial kinematic models of evolution are constructed. It is shown that the stellar structures that appear in the models are similar to the observed stellar streams. DOI: 10.1134/S106377292010008X
1. INTRODUCTION The study of the physics and evolution of star clusters is one of the primary fields of stellar astronomy. More than 10000 articles have been dedicated to this problem over the past hundred years. Currently, the research results in this area are presented annually in approximately 500 ADS articles (Astrophysics Data System, http://adsabs.harvard.edu/ads_abstracts.html). There are several reasons for the constant active interest of astronomers in the statistics, physics, and evolution of star clusters. The studies of different-aged clusters turned these astronomical objects into an effective and largely irreplaceable tool for understanding the evolution of stars and galaxies. The study of the star motion in clusters and the motion of the clusters themselves in the Galaxy has become the basis for examining the distribution of mass in clusters and galaxies. The history of the study of star clusters is an essential part of astronomy history itself. Even Democritus and Anaxagoras identified light spots in the sky as dense groups of stars indistinguishable to the naked eye. After Galileo introduced the telescope into astronomical practice, this allowed Messier (1781) [1] and W. Herschel (1786) [2] to start compiling the first catalogs that included star clusters. The growing accuracy of observational instruments enabled an astrometric estimation of distances to nearby stars (J. Herschel, 1815) [3] and over time allowed updating the data on star clusters (Dreyer, 1888) [4]. As early as the end of the 19th century, it was clear that the decay of star clusters led to the occurrence of stellar streams in the Galaxy (Proctor, 1869) [5]. Such streams themselves were discovered later; as we will see below, the study of their properties is currently given much attention.
At the beginning of the 20th century, the luminosity function (Fleming, 1904) [6] and the dynamics of stars in clusters [7, 8] became subjects of active study. In the 1930s, it became possible to estimate the masses of star clusters based on spectroscopy of the constituent stars (Shapley, 1930) [9]. In 1913, Chandrasekhar showed [10] that gravitationally bound clusters
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