Space Physics Flashcards
What is luminosity?
The total energy emitted per unit time by a star (power output)
What is the unit of luminosity?
Watts (W) or Joules per second (J/s)
How is luminosity related to the area of a star?
Luminosity is proportional to the surface area of the star
What is radiant flux intensity (F)?
The power per unit area received at Earth from a star
What is the formula for radiant flux intensity?
F = L / (4πd²)
What does ‘d’ represent in the formula F = L / (4πd²)?
The distance between Earth and the star
What assumptions are made in calculating radiant flux intensity?
Radiation is uniform and none is absorbed before reaching Earth
What is a standard candle?
An astronomical object with known luminosity
How are standard candles used?
To calculate the distance to stars using intensity measurements
What are Cepheid variable stars?
Stars whose brightness varies in a known period-luminosity relationship
What are Type 1A Supernovae?
Exploding stars with consistent peak luminosity
What is Wien’s Displacement Law?
λ_max * T = constant
What does a higher temperature imply about peak wavelength?
Shorter peak wavelength (bluer color)
What is the experimental value of the constant in Wien’s Law?
2.9 × 10⁻³ mK
What is a light year?
The distance light travels in a vacuum in one year
What does the Stefan-Boltzmann Law state?
L = 4πσr²T⁴
What is the experimental value of the Stefan-Boltzmann constant?
σ = 5.67 × 10⁻⁸ Wm⁻²K⁻⁴
How do you determine the radius of a star?
Use Wien’s Law for T
What does Hubble’s Law state?
The recession speed of galaxies is proportional to their distance (V = H₀d)
What is the experimental value of the Hubble constant?
H₀ = 2.4 × 10⁻¹⁸ s⁻¹
What does redshift indicate?
Galaxies are moving away from us; the universe is expanding
What is the formula for redshift?
Δλ/λ = v/c
What is the Big Bang Theory?
The idea that the universe began as a singularity ~13.7 billion years ago and has been expanding since
How does redshift support the Big Bang Theory?
Shows galaxies moving away
