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Astrophysics & Cosmology

65 cards · 🇺🇸 English

The physics of stars, black holes and the universe.

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Astrophysics

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  1. 1Astrophysics
    A science that applies the methods and principles of physics and chemistry in the study of astronomical objects and phenomena including the universe
  2. 2What distinction did James Keeler make about astrophysics?
    It seeks to ascertain the nature of the heavenly bodies—what they are, rather than where they are (which is studied in celestial mechanics)
  3. 3What subjects are studied in astrophysics?
    The Sun, other stars, galaxies, extrasolar planets, interstellar medium, and cosmic microwave background
  4. 4What properties of astronomical objects are examined in astrophysics?
    Luminosity, density, temperature, and chemical composition
  5. 5What physics disciplines do astrophysicists apply?
    Classical mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics
  6. 6What areas do theoretical astrophysicists study?
    Dark matter, dark energy, black holes, origin and ultimate fate of the universe, stellar evolution, galaxy formation, and cosmology
  7. 7Aristotelian view of celestial bodies
    They appeared to be unchanging spheres with uniform circular motion, made of fundamentally different matter (Fire or Aether) than the terrestrial sphere
  8. 8What discovery marked the beginning of astrophysics?
    William Hyde Wollaston and Joseph von Fraunhofer independently discovered dark lines (Fraunhofer lines) in the solar spectrum
  9. 9What did Kirchhoff deduce about dark lines in the solar spectrum?
    They are caused by absorption by chemical elements in the Solar atmosphere, proving the same elements found in the Sun and stars exist on Earth
  10. 10Harvard Classification Scheme
    A stellar classification system developed by Annie Jump Cannon, accepted for worldwide use in 1922, cataloging over 250,000 stars by 1924
  11. 11What diagram is still used today for classifying stars?
    The Hertzsprung-Russell diagram, discovered around 1920
  12. 12Eddington's speculation about stellar energy
    That the source was fusion of hydrogen into helium, liberating enormous energy according to Einstein's E=mc²
  13. 13Observational astronomy
    The division concerned with recording and interpreting data, in contrast with theoretical astrophysics which finds measurable implications of physical models
  14. 14What does radio astronomy study?
    Radiation with wavelength greater than a few millimeters, from cold objects like interstellar gas, cosmic microwave background, and pulsars
  15. 15What does infrared astronomy study?
    Radiation too long to be visible to the naked eye but shorter than radio waves, typically from objects colder than stars like planets
  16. 16Earliest kind of astronomy
    Optical astronomy
  17. 17What instruments are commonly used in optical astronomy?
    Telescopes paired with charge-coupled devices or spectroscopes
  18. 18Why are adaptive optics and space telescopes used in optical astronomy?
    Because Earth's atmosphere interferes with optical observations, limiting image quality
  19. 19What do ultraviolet, X-ray, and gamma ray astronomy study?
    Very energetic processes such as binary pulsars, black holes, and magnetars
  20. 20Why are space-based telescopes needed for X-ray and gamma ray astronomy?
    These types of radiation do not penetrate Earth's atmosphere well
  21. 21Examples of space-based X-ray observatories
    RXTE, Chandra X-ray Observatory, and Compton Gamma Ray Observatory
  22. 22IACTs
    Imaging Air Cherenkov Telescopes—ground-based instruments for observing high-energy gamma rays (examples: H.E.S.S. and MAGIC)
  23. 23What non-electromagnetic observations are made from Earth?
    Gravitational waves (extremely difficult to detect), neutrinos (primarily from the Sun), and cosmic rays (high-energy particles hitting the atmosphere)
  24. 24Why does the Sun have a special place in observational astrophysics?
    Due to its proximity, it can be observed in detail unparalleled by any other star, serving as a guide to understanding other stars
  25. 25Hertzsprung-Russell diagram used for
    Modeling stellar evolution by placing varieties of star types in their respective positions, representing the state from birth to destruction
  26. 26What tools do theoretical astrophysicists use?
    Analytical models (e.g., polytropes) and computational numerical simulations
  27. 27What do theoretical astrophysicists endeavor to do?
    Create theoretical models and figure out their observational consequences, helping observers look for data to refute or choose between models
  28. 28What topics do theoretical astrophysicists study?
    Stellar dynamics and evolution, galaxy formation, magnetohydrodynamics, large-scale structure, cosmic rays, general relativity, and physical cosmology
  29. 29What widely accepted models are now included in the Lambda-CDM model?
    The Big Bang, cosmic inflation, dark matter, dark energy, and fundamental theories of physics
  30. 30Celestial mechanics based on
    Kepler's laws of planetary motion

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