Astrophysics Flashcards
Intensity Ratio
1A/1B = 2.512MB-MA
Magnitude Difference
MA-MB = 2.5log(1A/1B)
Small Angle Formula
angular diameter-arcseconds/206265 = linear diameter/distance
Circular Velocity
VC = squareroot(GM/r-meters)
M = mass of central body (kg)
G = 6.67x10-11 m3/s2kg
* Answer in m/s
Compare LGP
LGPA/LGPB = (DA/DB)2
D = diameter
* Answer in times (x)
Resolving Power
a = 11.6/D(cm)
D = diameter (cm)
* Answer in arcseconds
Magnification
M = FO/FE
FO = focal length of objective
FE - focal length of eyepiece
Wien’s Law
~max = 3,000,000/T-degrees Kelvin
* Answer in nm
~max = .2987/T x 108Å
T = 2.9x108Å/peak ~
Stefan-Boltzmann Law
E = σT4(J/s/m2)
T = K
σ = 5.67 x 10-8J/m2s degree4
* Answer in J
Doppler Formula
Vr/c = triangle~/~o
Vr = radial velocity
c = 300,000 km/s
triangle~ = change in ~
~o = observed ~
(lmaoo you’re prob laughing when u see this)
Fusion Explained
E = mc2
m = kg
c = 3x108 m/s
Distance to Star
d = 206,265/p-arcseconds
p=parallax
* Answer in AU
F Ratio
focal length(mm)/objective diameter(mm)
Distance Modulus
mv - Mv = -5 + 5log(d)
d = 10 mV-MV+5/5 = pc
Luminosity of Star
L/Lo = (R/Ro)(T/To)
* Answer in times (x)
Mass of Binary System
MA + MB = a3/p2
M= solar masses
p = orbital period (yrs)
a = AU
Kepler’s 3rd Law
p2 = a3
p = orbital period (yrs)
a = distance (AU)
Mass-Luminosity Relation
L = M3.5
M = star mass in Mo
* Answer in times (x)
Life Expectancy
T = 1/M2.5
M = star mass in Mo
* Answer in O lifetimes x 10 billion = years
Schwarzschild Radius
RS = 2GM/C2
G = 6.67 x 10-11 m3/s2kg
C = 3 x 108 m/s
M = mass (kg)
* Answer in m
Hubble Law
Vr = Hd
Vr = velocity of recession of galaxy (km/s)
H = 20km/s/Mpc
d = distance (Mpc)
Redshift
Z = triangle~/~o
triangle~ = change in ~
~o = unshifted ~
Age of Universe
TU = 1/H x 1012years
H = 70 km/s/Mpc
* Answer in years
Distance-Rate-Time
d = rt
r = d/t
t = d/r
Newton’s Law of Gravity
F = Gm1m2/r^2
G = 6.67 x 10-11 m3/s2kg
m1m2 = masses of objects in kg
r = distance between the two masses (m)
F = the strength of the gravitational force (N)
Kepler’s 1st Law (Eccentricity)
e = c/a
Ratio
distance/(size/separation)
Frequency
v = c/~
1 AU
1.495979 x 1011m
1 parsec (AU)
206,265 AU
1 parsec (m)
3.085678 x 1016m
1 parsec (light years)
3.261633 light years
1 light year
9.46053 x 1015m
c, or the speed of light
2.997925 x 108m/s
G, or the gravitational constant
(6.67 x 10(-11)) + (m3/s2)/kg
M+
5.976 x 1024kg
R+
6,378.164 km
Mo
1.989 x 1030kg
Ro
6.9599 x 108m
Lo
3.826 x 1026kg
M of the Moon
7.350 x 1022 kg
R of the Moon
1738 km
M of H atom
1.67352 x 10-27 kg
1 arc minute (1’)
1/60o
1 arc second (1”)
1/60’
1 Megaton
1,000k000 of TNT = 4.5 x 1015 J
Gravity
6.67x10^-11Nm2/kg2
Force
F = G x m1m2/r2
Eccentricity
e2 = 1 -b2/a2
Barycenter
ma/mb = rb/ra
m = mass
r = distance
Keplar’s 3rd Law
p2 = (4π2/GM)a3
G = gravitational constant
M = mass of centeal object
P = solar years
Keplar’s 2nd Law
rotation of the a planet around a focal point results in the same time lapse passed over two opposite, but similar given areas. This proves acceleration as we near the focal point
1a supernovae
caused by white dwarves gaining mass of over 1.4 solar masses from its companion in a binary system
all 1a supernovaes have the same brightness and can determine intergalatic distances. They are brighter than type II
Type II supernovae
stars must be 8+ solar masses. Iron production because as elements run out for fusion. Heavy elements > atomic #26 are created in supernovae
Pulsars
stars core must be 1.4-3.2 solar masses. Emits beans of radiation at magnetic poles.
H-R Diagram
relates the absolute magnitudes and luminosities of stars with spectral types and temps. Can reveal characteristics in stars and predict locations of new stars. Measured in kelvin or spectral class (O B A F G K M)