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
1AU DEFINITION
average distance between the earth and the sun aprox. 1.5times 10 to the power of 11
1Ly
the distance travelled by EM waves in 1 year
1Pc
