diff --git a/src/18_galactic_bimodality.md b/src/18_galactic_bimodality.md index d42561b..163041b 100644 --- a/src/18_galactic_bimodality.md +++ b/src/18_galactic_bimodality.md @@ -1,31 +1,32 @@ # Galactic bimodality -3. GALACTIC BIMODALITY - -Galaxies can also be divided into the two most common types: ***elliptical*** and ***spiral*** (see Fig. 1.8). According to many estimates152 , these types of galaxies account for more than 70% of the total number of galaxies in the Universe. If we take into account that SO-type galaxies, which are a kind of intermediate class between spiral and elliptical galaxies, are the third most common, the other classes of galaxies account for no more than 15% of the total number of galaxies. What distinguishes the two main types of galaxies in the most general terms? +Galaxies can also be divided into the two most common types: ***elliptical*** and ***spiral*** (see Fig. 1.8). According to many estimates[^ref-152], these types of galaxies account for more than 70% of the total number of galaxies in the Universe. If we take into account that SO-type galaxies, which are a kind of intermediate class between spiral and elliptical galaxies, are the third most common, the other classes of galaxies account for no more than 15% of the total number of galaxies. What distinguishes the two main types of galaxies in the most general terms? SHAPE AND STRUCTURE. Elliptical galaxies have a very *simple* shape and internal structure. -*"Elliptical* galaxies, unlike the others, are structureless. Regarding the structure of elliptical galaxies, we can speak only in terms of the distribution of densities in them along the radius "153. *Spiral* galaxies have a complex form of logarithmic spiral arms, disks, nucleus, core, nucleus and many other features of the structure. Moreover, every spiral galaxy has a halo, which is an elliptical formation of globular clusters of stars. Virtually every spiral *galaxy* has an inset, an *elliptical* inside it +> Elliptical galaxies, unlike the others, are structureless. Regarding the structure of elliptical galaxies, we can speak only in terms of the distribution of densities in them along the radius[^ref-153] -*"galaxy*" (see Fig. 1.52). +*Spiral* galaxies have a complex form of logarithmic spiral arms, disks, nucleus, core, and many other features of the structure. Moreover, every spiral galaxy has a halo, which is an elliptical formation of globular clusters of stars. Virtually every spiral *galaxy* has an inset, an *elliptical* inside it *"galaxy"* (see Fig. 1.52). -AGE. The age of most galaxies is estimated by astrophysicists to be about the *same*. They all formed at the very beginning of the expansion of the Universe, at the moment when it crossed the threshold of 1027 cm. +AGE. The age of most galaxies is estimated by astrophysicists to be about the *same*. They all formed at the very beginning of the expansion of the Universe, at the moment when it crossed the threshold of \\(10^{27}\\) cm. -At the same time in *elliptical* galaxies, ***star formation has practically stopped***, they have no material \- gas and dust, and they consist of old type II population stars. +At the same time in *elliptical* galaxies, ***star formation has practically stopped***, they have no material — gas and dust — and they consist of old population II stars. -In *spiral* galaxies, old stars form a spherical "insert" \- the halo, while dust and new stars are mainly distributed in the disk and spiral branches. In spiral galaxies, the ***process of star birth continues***. +In *spiral* galaxies, old stars form a spherical "insert" — the halo — while dust and new stars are mainly distributed in the disk and spiral branches. In spiral galaxies, the ***process of star birth continues***. That is why we can say that ***elliptical galaxies*** (here we include elliptical components of spiral galaxies) are *old systems of the first generation,* and ***spiral*** galaxies (in terms of their specific structure) are young systems of the second epoch of star formation. -SIZES AND MASSES. The largest in size are *spiral* galaxies, the largest of them exceeding a diameter of 1023 cm. The author was unable to find in the literature any mention of spiral galaxies with sizes smaller than 1022 cm. On the other hand, *all dwarf galaxies are elliptical* and for them the lower threshold is 1020 cm. +SIZES AND MASSES. The largest in size are *spiral* galaxies, the largest of them exceeding a diameter of \\(10^{23}\\) cm. The author was unable to find in the literature any mention of spiral galaxies with sizes smaller than \\(10^{22}\\) cm. On the other hand, *all dwarf galaxies are elliptical*, and for them the lower threshold is \\(10^{20}\\) cm. -In addition, according to statistical data154 , the mass range of *spiral* galaxies lies within 109-1012 solar masses. For elliptical galaxies, however, this range is strongly shifted towards low masses: 105-1012 solar masses. This indicates that *spiral galaxies are on average larger and more massive, while elliptical galaxies are on average smaller and less massive*. +In addition, according to statistical data¹⁵⁴, the mass range of *spiral* galaxies lies within \\(10^9{-}10^{12}\\) solar masses. For elliptical galaxies, however, this range is strongly shifted towards low masses: \\(10^5{-}10^{12}\\) solar masses. This indicates that *spiral galaxies are on average larger and more massive, while elliptical galaxies are on average smaller and less massive*. -ENTRY INTO CLUSTERS. Galaxy clusters include about 76% of elliptical galaxies and only less than 50% of spiral galaxies155. +ENTRY INTO CLUSTERS. Galaxy clusters include about 76% of elliptical galaxies and only less than 50% of spiral galaxies¹⁵⁵. -So, we see that the Universe is populated mainly by two types of galaxies. ***Elliptical galaxies*** are older, on average smaller in size, simpler in shape and structure, they are part of the metagalactic cellular skeleton of clusters. ***Spiral galaxies are*** younger, the largest and most massive, they are free from the structural skeleton of the Metagalaxy. +So, we see that the Universe is populated mainly by two types of galaxies. ***Elliptical galaxies*** are older, on average smaller in size, simpler in shape and structure, and they are part of the metagalactic cellular skeleton of clusters. ***Spiral galaxies are*** younger, the largest and most massive, and they are free from the structural skeleton of the Metagalaxy. -It is very important, to note that **there is a clear distinction** between these two types in a multitude of parameters, which indicates their fundamental difference. +It is very important to note that **there is a clear distinction** between these two types in a multitude of parameters, which indicates their fundamental difference. -Based on these qualitative data, we can PROPOSE that *elliptical* galaxies belong ***to the first mode of*** the assumed bimodal size distribution of galaxies, while *spiral galaxies belong* to ***the second mode***. And by analogy with atoms and stars, we can PROPOSE that there is a gap in the statistical distribution of galaxies by size between these modes. +Based on these qualitative data, we can **PROPOSE** that *elliptical* galaxies belong ***to the first mode*** of the assumed bimodal size distribution of galaxies, while *spiral galaxies belong* to ***the second mode***. And by analogy with atoms and stars, we can **PROPOSE** that there is a gap in the statistical distribution of galaxies by size between these modes. + +[^ref-152]: *Vorontsov-Vel'yaminov B.A.* Essays on the Universe. Moscow: Nauka, 1969. +[^ref-153]: *Vorontsov-Vel'yaminov B.A.* Essays on the Universe. Moscow: Nauka, 1969. С. 130. \ No newline at end of file