Introduction to Astrophysics

How can we study the Universe we live in using the only available information it provides us with: light ?

This course provides an overview of the physical phenomena at play in the astronomical objects surrounding us, from planets and stars to the cosmic filaments, from galaxies such as our own Milky Way to large galaxy clusters. The course emphasizes the links between theoretical predictions and observations.

In this course, you will learn the basics of astrophysics using simplified mathematical developments. In particular, you will learn the role played by gravity in astrophysics, including gravitational lensing, and how matter and radiation interact. The material in this course is essential to follow more advanced astrophysics courses.

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Week 1:
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** Video 1.1: (23:00 min)
- Parallaxes and Parsec
- General Introduction
- Mass and Distance scales

** Video 1.2: (14:42 min)
- Kepler's Laws

** Vidéo 1.3: (11:58 min)
- Virial Theorem
- Potential Energy of a Sphere

** Vidéo 1.4: (4:38 min)
- Numerical Illustrations of Virial Theorem

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Week 2:
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** Video 2.1: (23:55 min)
- Radiation processes in Astrophysics
- Line and Continuum Radiation
- Examples of Spectra
- Radiated Energy and Units
- Radiation Pressure
- Bremsstrahlung and Synchrotron Radiations

** Video 2.2: (20:15)
- Black Body Radiation
- Total Luminosity (sigma T^4)
- Wien's Law
- Atomic Emission Lines
- The Case of Hydrogen

** Video 2.3: (21:00)
- How to Measure Radiation
- Flux, Luminosity, Filters
- Illustration: How do we Make True Color Images?
- Magnitudes
- Color of Celestial Bodies
- Distance Modulus

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Week 3:
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** Video 3.1: (23:44)
- Doppler Effect
- Doppled Measurement
- Stellar Rotation
- Exoplanets and Stellar Radial Velocities
- Hubble Law

** Video 3.2: (32:22)
- Interstellar Medium
- Nebular Emission, Stromgroen Sphere
- Absorption, diffusion (Mie et Rayleigh)
- Optical Depth
- Redening

** Video 3.3: (18:12)
- Tidal Forces
- Influence on Moon-Earth Distance
- Distance to the Moon Using Laser Measurements

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Week 4:
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** Video 4.1: (12:14)
- Roche Limit
- Example of Saturn's Rings
- Example of a Comet Disrupted by Jupiter's Tidal Forces

** Vidéo 4.2 (13:43)
- Cometary Tails and Radiation Pressure

** Video 4.3: (15:08)
- Energy Balance
- Global Warming

** Video 4.4:
- Planetary Atmospheres
- Hydrostatic Equilibrium
- Atmospheric height-scale

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Week 5:
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** Video 5.1:
- Stellar Formation
- Free-fall Time
- Jeans' Mass and radius
- Kelvin-Helmholtz Time
- Stellar Energy Balance

** Video 5.2:
- HR Diagram
- Spectral Classification
- Effect of Redening
- Radius-Luminosiy Relation

** Video 5.3:
- Stellar Evolution in the HR Diagram
- Stellar Deaths
- Supernovae, Planetary Nebulae, White Dwarfs, Neutron Stars
- Age of Stellar Clusters

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Week 6:
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** Video 6.1:
- Galaxies: General Description
- Morphological Classification

** Video 6.2:
- Numerical Illustrations

** Video 6.3
- The Milky-Way
- Oort Constants and Galactic Motion

** Video 6.4:
- Rotation Curves of Spiral Galaxies
- Elliptical galaxies and the Virial Theorem
- Galaxy Clusters
- Dark Matter

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Week 7:
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** Video 7.1:
- Big Bang: Basic Presentation
- Hubble Expansion
- Cosmological Redshift
- Cosmic Background Radiation

** Video 7.2:
- Distance Ladder
- Hubble Diagram
- Cepheides as Distance Indicators
- Supernovae as Distance Indicators

** Video 7.3:
- Gravitational Lenses
- Deflection Angle
- Properties of Gravitational Lenses
- Light (apparent) Magnification
- Einstein Radius
- Caustics and Critical Lines

** Complementary video on time delays in gravitationally lensed quasars an cosmologocal applications.