Unit 19/20 - Astrophysics Flashcards
What are the three cosmological assumptions?
- Universe is homogenous
- Universe is isotopic
- Laws of physics are universal
What is the Chandrasekhar limit?
1.44 x mass of the sun
What happens when the mass is greater than the Chandrasekhar limit?
Pushes electrons into protons and it becomes a neutron star
What is the Schwarzschild radius?
The event horizon for light where it cannot escape if it goes further in
What is the relationship between Flux and distance ?
Flux or luminosity follows the inverse square rule. As distance double the light intensity quarters
What is Refraction?
Change in direction of a wave direction due to a change in the medium
What is Diffraction ?
Bending of light around corners of an obstacle or aperture into the region of geometrical shadow of the obstacle
What is reflection?
A wave of energy bounces back
What light diffracted the most and least?
Red is diffracted the most and purple the least
What does redshift mean?
Source is moving away from, receiver. Longer wavelength, lower frequency
What does blueshift mean?
Source moving towards receiver. Shorter wavelength, higher frequency
What did Hubble realise?
the further away a galaxy was, the greater its red shift
What is Hubble’s law?
the speed of a receding galaxy is directly proportional to its distance
What assumption did Hubble make?
The current expansion is equal to the expansion rate the entirety of the universe
What is the Doppler effect?
A change in perceived wavelength of a wave due to a relative change in position between the source and receiver
