Px158 Revision Flashcards
(12 cards)
What is the surface area of a sphere?
4pir^2
What is the formula for calculating absolute magnitudes?
M2 - M1 = -2.5log(f2/f1) where F is flux?
What is the formula relating absolute magnitudes and apparent magnitudes?
m - M = 5log(d/(10pc))
What is the formula relating distance to parallax?
d(pc) = 1/parallax
What is the Stephan Boltzmann law
L = 4piR^2sigmaT^4
What is the formula for distance with redshift?
Z = H0*d/c
What are three pieces of evidence for dark matter?
- gravitational lensing around galaxies implies more matter than can be accounted for baryonically
- the rotational velocities of outer galaxies remains nearly constant, implying more mass
- lambdaCDM simulations require dark matter for the universe to evolve canonically
What is the focal ratio?
Focal length/diameter
What is the formula relating two apparent magnitudes?
m2 - m1= -2.5log(f2/f1)
What is the formula for the diffraction limit of a particular wavelength of light?
D.L = 1.22 lambda/D
How do you calculate the altitude of a star given a latitude?
90-(declination if star - latitude)
What is the declination of the sun during the summer solstice at noon?
+23.5
