{"title":"分子丝演变的 MHD 模型","authors":"I. M. Sultanov, S. A. Khaibrakhmanov","doi":"10.1134/S1063772924700070","DOIUrl":null,"url":null,"abstract":"<p>We perform numerical magnetohydrodynamic (MHD) simulations of the gravitational collapse and fragmentation of a cylindrical molecular cloud with the help of the FLASH code. The cloud collapses rapidly along its radius without any signs of fragmentation in the simulations without magnetic field. The radial collapse of the cloud is stopped by the magnetic pressure gradient in the simulations with parallel magnetic field. Cores with high density form at the cloud’s ends during further evolution. The core densities are <span>\\(n \\approx 1.7 \\times {{10}^{8}}\\)</span> and <span>\\(2 \\times {{10}^{7}}\\)</span> cm<sup>–3</sup> in the cases with initial magnetic field strengths <span>\\(B = 1.9 \\times {{10}^{{ - 4}}}\\)</span> and <span>\\(6 \\times {{10}^{{ - 4}}}\\)</span> G, respectively. The cores move toward the cloud’s center with supersonic speeds <span>\\(\\left| {{{{v}}_{z}}} \\right| = 3.6\\)</span> and <span>\\(5.3\\)</span> km/s. The sizes of the cores along the filaments radius and filament’s main axis are <span>\\({{d}_{r}} = 0.0075\\)</span> pc and <span>\\({{d}_{z}} = 0.025\\)</span> pc, <span>\\({{d}_{r}} = 0.03\\)</span> pc and <span>\\({{d}_{z}} = 0.025\\)</span> pc, respectively. The masses of the cores increase during the filament evolution and lie in range of <span>\\( \\approx {\\kern 1pt} (10{-} 20){\\kern 1pt} {{M}_{ \\odot }}\\)</span>. According to our results, the cores observed at the edges of molecular filaments can be a result of the filament evolution with parallel magnetic field.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 1","pages":"60 - 66"},"PeriodicalIF":1.1000,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"MHD Modeling of the Molecular Filament Evolution\",\"authors\":\"I. M. Sultanov, S. A. Khaibrakhmanov\",\"doi\":\"10.1134/S1063772924700070\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>We perform numerical magnetohydrodynamic (MHD) simulations of the gravitational collapse and fragmentation of a cylindrical molecular cloud with the help of the FLASH code. The cloud collapses rapidly along its radius without any signs of fragmentation in the simulations without magnetic field. The radial collapse of the cloud is stopped by the magnetic pressure gradient in the simulations with parallel magnetic field. Cores with high density form at the cloud’s ends during further evolution. The core densities are <span>\\\\(n \\\\approx 1.7 \\\\times {{10}^{8}}\\\\)</span> and <span>\\\\(2 \\\\times {{10}^{7}}\\\\)</span> cm<sup>–3</sup> in the cases with initial magnetic field strengths <span>\\\\(B = 1.9 \\\\times {{10}^{{ - 4}}}\\\\)</span> and <span>\\\\(6 \\\\times {{10}^{{ - 4}}}\\\\)</span> G, respectively. The cores move toward the cloud’s center with supersonic speeds <span>\\\\(\\\\left| {{{{v}}_{z}}} \\\\right| = 3.6\\\\)</span> and <span>\\\\(5.3\\\\)</span> km/s. The sizes of the cores along the filaments radius and filament’s main axis are <span>\\\\({{d}_{r}} = 0.0075\\\\)</span> pc and <span>\\\\({{d}_{z}} = 0.025\\\\)</span> pc, <span>\\\\({{d}_{r}} = 0.03\\\\)</span> pc and <span>\\\\({{d}_{z}} = 0.025\\\\)</span> pc, respectively. The masses of the cores increase during the filament evolution and lie in range of <span>\\\\( \\\\approx {\\\\kern 1pt} (10{-} 20){\\\\kern 1pt} {{M}_{ \\\\odot }}\\\\)</span>. According to our results, the cores observed at the edges of molecular filaments can be a result of the filament evolution with parallel magnetic field.</p>\",\"PeriodicalId\":55440,\"journal\":{\"name\":\"Astronomy Reports\",\"volume\":\"68 1\",\"pages\":\"60 - 66\"},\"PeriodicalIF\":1.1000,\"publicationDate\":\"2024-05-08\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Astronomy Reports\",\"FirstCategoryId\":\"101\",\"ListUrlMain\":\"https://link.springer.com/article/10.1134/S1063772924700070\",\"RegionNum\":4,\"RegionCategory\":\"物理与天体物理\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"ASTRONOMY & ASTROPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Astronomy Reports","FirstCategoryId":"101","ListUrlMain":"https://link.springer.com/article/10.1134/S1063772924700070","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
We perform numerical magnetohydrodynamic (MHD) simulations of the gravitational collapse and fragmentation of a cylindrical molecular cloud with the help of the FLASH code. The cloud collapses rapidly along its radius without any signs of fragmentation in the simulations without magnetic field. The radial collapse of the cloud is stopped by the magnetic pressure gradient in the simulations with parallel magnetic field. Cores with high density form at the cloud’s ends during further evolution. The core densities are \(n \approx 1.7 \times {{10}^{8}}\) and \(2 \times {{10}^{7}}\) cm–3 in the cases with initial magnetic field strengths \(B = 1.9 \times {{10}^{{ - 4}}}\) and \(6 \times {{10}^{{ - 4}}}\) G, respectively. The cores move toward the cloud’s center with supersonic speeds \(\left| {{{{v}}_{z}}} \right| = 3.6\) and \(5.3\) km/s. The sizes of the cores along the filaments radius and filament’s main axis are \({{d}_{r}} = 0.0075\) pc and \({{d}_{z}} = 0.025\) pc, \({{d}_{r}} = 0.03\) pc and \({{d}_{z}} = 0.025\) pc, respectively. The masses of the cores increase during the filament evolution and lie in range of \( \approx {\kern 1pt} (10{-} 20){\kern 1pt} {{M}_{ \odot }}\). According to our results, the cores observed at the edges of molecular filaments can be a result of the filament evolution with parallel magnetic field.
期刊介绍:
Astronomy Reports is an international peer reviewed journal that publishes original papers on astronomical topics, including theoretical and observational astrophysics, physics of the Sun, planetary astrophysics, radio astronomy, stellar astronomy, celestial mechanics, and astronomy methods and instrumentation.