. "Cosmology"@en . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . "Interstellar medium"@en . . "6" . "The space between the stars is filled with matter, magnetic fields, and radiation. This course describes this Interstellar Medium (ISM) as an integral part of galactic ecosystems. It provides an overview of the constituents of the ISM (ionized, atomic, and molecular gas; dust; electromagnetic radiation; magnetic fields; cosmic rays), their relation and interaction, and the different environments in which these are encountered (the multi-phase models of the ISM), as well as the corresponding observational diagnostics. It discusses the physical processes that govern the interactions within the ISM and with stars (radiation, shocks), and it highlights the relationships between the ISM and stars and their host galaxies (birth and death of stars; supernovae; nuclei of active galaxies).\r\n\r\nThe following themes are covered:\r\n\r\nThe Galactic ecosystem: HII regions, reflection nebulae, SNRs, dark clouds. Distribution in the Milky Way. ISM mass budget. Objects vs. phases. Properties of ISM phases and cycle of material between phases. Energy sources and energy densities in the ISM.\r\n\r\nFundamental physical conditions: Maxwell velocity distribution and kinetic temperature. Lack of LTE. Excitation temperature. Statistical equilibrium.\r\n\r\nInteraction of radiation with interstellar matter: Description of the radiation field: radiation intensity, specific energy density. Definition of the Einstein coefficients for absorption, spontaneous emission and stimulated emission. Relation between the Einstein coefficients. Relation to cross section. Line profiles. Equation of transfer for radiation. Relation of emissivity and absorption coefficient to Einstein coefficients. Optical depth and source function. Kirchhoff's law. Population inversion and masers.\r\n\r\nThe HI 21cm line and the 2-phase ISM: the HI 21cm line. Equation of transfer in terms of Rayleigh-Jeans brightness temperature. Spin temperature. Deriving HI column density and mass from optically thin HI emission. HI absorption. Emission-absorption observations and the evidence for the 2-phase ISM.\r\n\r\nIonization and recombination: photoelectric absorption and radiative recombination. The hydrogen spectrum. Recombination lines. Case A and case B recombination spectra. Measuring star formation using recombination lines.\r\n\r\nHII regions: Strömgren spheres. Ionization of hydrogen, helium, and heavier elements. The role of dust. Structure and evolution of HII regions.\r\n\r\nCollisional excitation: Critical density for a 2-level system. Behaviour of the population ratio in limiting cases of very high and very low density. Implications for HI spin temperature. Generalization to multi-level systems. Line ratios as diagnostics for density, temperature and abundance.\r\n\r\nMolecules and their excitation: Born-Oppenheimer approximation, electronic, vibrational and rotational transitions; spectra of diatomic molecules; ortho- and para-H2. Molecular excitation and radiative trapping.\r\n\r\nMolecular lines and molecular clouds: Radiative trapping. Solving excitation and radiative transfer for very optically thick lines: escape probabilities. Using CO as a tracer of the mass of molecular clouds. Global properties of molecular clouds. The X-factor.\r\n\r\nInterstellar dust: Extinction curves and reddening. Definitions of absorption, scattering and extinction cross sections. Constraints on dust models. Constituents of interstellar dust. PAHs. Radiative heating and cooling of dust grains. Infrared emission.\r\n\r\nThermal balance of the ISM: Heating and cooling of HII regions. HII region temperatures. Heating and cooling of the neutral ISM and the 2-phase model.\r\n\r\nShocks: J-type and C-type shocks in molecular clouds. Supernova shocks.\r\n\r\nThe 3-phase model of the ISM.\r\n\r\nPDRs, XDRs, and the extragalactic ISM: Formation and destruction of H2. Self-shielding. PDRs and XDRs. The ISM at low metallicity and in the early Universe.\n\nOutcome:\nupon completion of this course you will be able to explain the basic physical conditions in the Interstellar Medium (ISM) and its various constituents, and explain the relation between these constituents. You will also be able to carry out basic calculations of physical conditions in the ISM under simple assumptions.\r\n\r\nSpecifically, upon completion of this course you will be able to:\r\n\r\nExplain the fundamental physical conditions in the ISM, including concepts such as kinetic temperature and excitation temperature\r\n\r\nExplain and apply the principle of detailed balance in the ISM\r\n\r\nSolve simple radiative transfer problems as applied to the ISM\r\n\r\nExplain the 2-phase model of the ISM, including the observational evidence for it\r\n\r\nExplain photoionization-recombination balance and the resulting recombination spectra\r\n\r\nCalculate simple properties of spherical HII regions\r\n\r\nExplain collisional excitation including the concept of critical density and the limiting cases at high and low densities\r\n\r\nCalculate level populations of atoms and molecules in optically thin conditions\r\n\r\nExplain radiative trapping, its effect on the line spectrum and level populations, and radiative transfer and excitation under optically thick conditions\r\n\r\nExplain the spectra of simple molecules and the use of molecular lines as probes of physical conditions\r\n\r\nExplain the properties, role and observable effects of dust in the ISM\r\n\r\nExplain the thermal balance in the various constituents of the ISM\r\n\r\nCalculate ISM temperatures under simplified conditions\r\n\r\nExplain the nature and effects of shocks in the ISM\r\n\r\nExplain the 3-phase model of the ISM\r\n\r\nExplain the nature and physics of PDRs, XDRs, and of the ISM at low metallicity and in the early Universe" . . "Presential"@en . "TRUE" . . "Master of Astronomy"@en . . "https://www.universiteitleiden.nl/en/education/study-programmes/master/astronomy" . "120"^^ . "Presential"@en . "Within the two-year Astronomy master’s programme, you can choose from seven specialisations, ranging from fundamental or applied astronomy research in cosmology, instrumentation or data science, to combinations of astronomy research with education, management or science communication.\n\nThe two-year Astronomy master’s programme offers seven specialisations:\n1. Astronomy Research: you follow a tailor-made programme to become an independent and resourceful scientist.\n2. Astronomy and Instrumentation: obtain in-depth knowledge of state of the art approaches to develop high tech astronomy instruments.\n3. Astronomy and Data Science: focus on development and application of new data mining technologies, fully embracing modern astronomy as a data rich branch of science. \n4. Astronomy and Cosmology: discover all aspects of modern astrophysics, including extensive observation, interpretation, simulation and theory.\n5. Astronomy and Business Studies: combine training in astronomy with education in management and entrepreneurship.\n6. Astronomy and Science Communication and Society: combine research with all aspects of science communication, such as journalism and universe awareness education.\n7. Astronomy and Education (taught partly in Dutch): prepare yourself for a career in teaching science at high school level.\n\nOutcome:\nDuring the programme, you learn to perform academically sound research and evaluate scientific information independently and critically. Without exception, you actively participate in current research within the institute and are individually supervised by our international scientific staff. Students with a Leiden degree in Astronomy become strong communicators and collaborators and can easily operate in an international setting. You will acquire extensive astronomical research experience and highly advanced analytical and problem solving skills."@en . . . . . . "2"@en . "FALSE" . . "Master"@en . "Thesis" . "2314.00" . "Euro"@en . "19600.00" . "Mandatory" . "With a master’s degree in Astronomy you are well prepared for jobs in research, industry and the public sector, including technological, financial and consultancy companies, research institutes, governments and science communication organizations.\n\nMost graduates holding a MSc degree in Astronomy from Leiden University find work in many different capacities, including:\r\n1. Research: universities, observatories, research institutes\r\n2. Industry and consultancy: ICT, R&D, telecom, high technology, aerospace\r\n3. Finance: banking, insurance, pension funds\r\n4. Public sector: governments, policy makers, high schools\r\n5. Science communication: journalism, popular writing, museums\r\n6. Typical jobs for Astronomy graduates include:\r\n\r\nScientific researcher (postdoc, research fellow, professor)\r\n1. R&D engineer\r\n2. Consultant\r\n3. Data scientist, statistician\r\n4. Policy advisor, public information officer (e.g. Ministry of Foreign Affairs)\r\n5. High school physics teacher\r\n6. Scientific editor for magazines, newspapers and other media\n\nIf you want to get more deeply involved in research after graduating in Astronomy, consider pursuing a PhD at Leiden Observatory. If you have completed the Leiden master’s degree programme in Astronomy, you are directly eligible for admission to our PhD programme."@en . "7"^^ . "TRUE" . "Upstream"@en . . . . . . . . . . . . . . . . . . . . . . . . . . . .