astrophysics Flashcards
revision
Refracting Telescopes
– Use lenses to bend and focus light.
Reflecting Telescopes
– Use mirrors (e.g., Newtonian & Cassegrain).
Chromatic Aberration
– Light of different wavelengths refracts differently (only in refractors).
Spherical Aberration
– Imperfect mirror shape causes blurred images.
Luminosity
– Total energy radiated per second (depends on temperature & radius)
Stefan-Boltzmann Law
– 𝐿=𝜎𝐴𝑇^4 , where L is luminosity.
Wien’s Law
– 𝜆𝑇=2.9×10^−3mK (Hotter = Bluer)
HR Diagram
– Plots luminosity vs. temperature (Main Sequence, Giants, White Dwarfs).
Spectral Classes
– OBAFGKM (Oh Be A Fine Girl Kiss Me).
Nebula
– Cloud of dust and gas, birthplace of stars.
What is the Main Sequence phase of a star?
Hydrogen fusion occurs in the core, and the star is in a stable phase.
What happens during the Red Giant/Supergiant phase?
Hydrogen runs out, causing the outer layers to expand.
What is a White Dwarf?
A small, dense remnant of a Sun-like star.
What is a Supernova?
A massive explosion that occurs if the core collapses.
What is a Neutron Star?
The core remains after a supernova, and it is extremely dense.
What is a Black Hole?
A gravitational collapse that occurs beyond the neutron star stage.
the focal length definition
the focal length, f, is the distance between the lens axis and the focal plane
