P2 astrophysics

• What is the name of the scale that measures brightness of a star for a fixed distance?

  Absolute Magnitude
• What do the axes of the HR diagram represent?

  X axis: decreasing temperature; Y axis: Absolute magnitude/Luminosity
• If Star A has an absolute magnitude of -3 and Star B has 1, which star has the highest luminosity?

  Star A
• What types of stars are represented by letters A, B, and C in the HR diagram?

  • A: Red Giant/Supergiant
  • B: Main Sequence
  • C: White Dwarf
• Summarize the Big Bang Theory.

  The universe expanded from a dense point 14 billion years ago
• What are two pieces of evidence that support the Big Bang Theory?

  • Cosmic Microwave Background Radiation (CMB)
  • Redshift of distant galaxies
• How does Cosmic Microwave Background Radiation (CMB) support the Big Bang Theory?

  CMB is leftover thermal energy from the Big Bang
• How does redshift provide evidence for the Big Bang Theory?

  Greater redshift indicates galaxies are moving away faster
• What is redshift?

  Wavelength increases as a galaxy moves away
• What is blueshift?

  Wavelength decreases as an object moves towards Earth
• How are observed frequency and wavelength affected by redshift and blueshift?

  • Redshift: Wavelength increases, frequency decreases
  • Blueshift: Wavelength decreases, frequency increases
• What is the equation linking change in wavelength, reference wavelength, recessional speed of galaxy, and speed of light?

  Change in wavelength = recessional speed / speed of light
• How do redshift observations from distant galaxies support the Big Bang Theory?

  All galaxies are moving away, indicating expansion