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Useful overview of the Astrophysics I Equations
Typology: Cheat Sheet
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∆θ = 1. 22 λ/D SNR = Nstar/
√
Ntotal Ntotal = Nstar + p × nsky
d = 1/p D = θd λν = c E = hν
ν
2 hν
3
c
2
e
hν/kT − 1
λ max
T = 0.29 cm K hν max
= 2.8kT
L = 4πr
2
∗
σT
4
= f 4 πd
2
1
r 1
2
r 2
ω
2
=
1
2
a
3
1
2
) sin
3
i =
τ (v 1 obs
3
2 πG
dM
dr
= 4πr
2
ρ(r)
dP
dr
GM ρ
r
2
dL
dr
= 4πr
2
ρǫ
dT
dr
3 Lκρ(r)
16 πr
2 acT
3
l = 1/nσ = 1/ρκ P gas
= nkT =
ρ
m ¯
kT E K
f
kT P rad
aT
4
EG = 2μc
2
(παZAZB )
2
α =
e
2
¯h
F = q 1
q 2
/r
2 λ = h/p ∆x∆p x
h
dN =
2 s + 1
exp
(
E−μ(T )
kT
)
d
3 pdV
h
3
ne =
8 π
3 h
3
p
3
f
∫
n(p)pvdp Pe =
(
3
8 π
) 2 / 3 h
2
5 m e
n
5 / 3
e
(
3
π
) 2 / 3 h
2
20 m e
m
5 / 3
p
(
Z
) 5 / 3
ρ
5 / 3
e
8 πc
3 h
3
p
4
f
(
3
8 π
) 1 / 3
hc
4 m
4 / 3
p
(
Z
) 4 / 3
ρ
4 / 3
r wd
h
2
20 m e
m
5 / 3
p G
(
Z
) 5 / 3
− 1 / 3
r wd
9
cm
(
Z
) 5 / 3
(
) − 1 / 3
ch
⊙
Erot =
Iω
2
I =
M r
2
L =
2
r
6
ω
4
6 c
3
sin
2
θ
r s
c
2
= (3 km)
⊙
(ds)
2
=
(
rc
2
)
(cdt)
2
−
(
rc
2
) − 1
(dr)
2
− (rdθ)
2
− (r sin θdφ)
2
tide
m
2
∆r
r
3
dE th
(
GM dM
r
GM dM
r + ∆r
)
dE
dt
dr
r
2
= 2(2πr)σT
4
dr
T (r) =
(
8 πσ
) 1 / 4
r
− 3 / 4
L ≈
2 r in
E
4 πcGM m p
σ T
38
erg/s)
⊙
ρJ =
4 πM
2
(
3 kT
G m¯
) 3
Rrec = α(T )x
2
n
2
Rion = nphotonn(1 − x)σionc rstrom =
(
4 παn
2
) 1 / 3
n 2
n 1
g 2
g 1
e
−hν/kT
− 8 erg cm g
− 2 h = 6. 63 × 10
− 27 erg s c = 3. 0 × 10
10 cm/s
k = 1. 38 × 10
− 16 erg/K = 8. 62 × 10
− 5 eV/K
σ = 5. 67 × 10
− 5
erg cm
− 2
K
− 4
a = 4σ/c = 7. 6 × 10
− 15
erg cm
− 3
K
− 4
m p
− 24 g m e
− 28 g
e = 4. 8 × 10
− 10
statcoulombs 1 statcoulomb = 1 erg
1 / 2
cm
1 / 2
σ T
− 25 cm
2
1 pc = 3. 086 × 10
18
cm
CGS units: erg = g cm
2 s
− 2 = dyne cm
Sun:
⊙
33 g R ⊙
10 cm L ⊙
33 erg/s
E⊙
= 5800 K ρ¯ ⊙
= 1.4 g cm
− 3 T C⊙
6 K ρ C⊙
= 150 g cm
− 3