Astronomy and cosmology

What you'll learn

• Understand the term luminosity as the total power of radiation emitted by a star.
• Recall and use the inverse square law for radiant flux intensity F in terms of the luminosity L of the source F = L/(4πd²).
• Understand that an object of known luminosity is called a standard candle.
• Understand the use of standard candles to determine distances to galaxies.
• Recall and use Wien’s displacement law λmax ∝ 1/T to estimate the peak surface temperature of a star.
• Use the Stefan–Boltzmann law L = 4πσr²T⁴.
• Use Wien’s displacement law and the Stefan–Boltzmann law to estimate the radius of a star.
• Understand that the lines from the emission spectra from distant objects show an increase in wavelength from their known values.
• Use Δλ/λ ≈ Δf/f ≈ v/c for the redshift of electromagnetic radiation from a source moving relative to an observer.
• Explain why redshift leads to the idea that the Universe is expanding.
• Recall and use Hubble’s law v ≈ H₀d and explain how this leads to the Big Bang theory.

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