[g.p]: Astro Memento

Astro Memento

Astronomy » Astro Memento

Table of Contents

Optique Instrument

		NEXSTAR 5SE `F=1250 mm D=127 mm`
Ouverture / Aperture `F: focale instrument D: diamètre instrument / diameter`	(1) ${F\over D}$	9.84 = 1250/127 `ciel profond: F/D>10 planétaire: F/D<10 mixte: F/D=10`
Grossissement / Magnification `F: focale instrument f: focale oculaire / eyepiece`	(2) $G = {F\over f}$	50x = 1250/25 130x = 1250/9.5
Grossissement Min, Max	(3) $min = {D\over 7};max = {D * 2.5}$	18x = 127/7 317x = 127*2.5
Pouvoir séparateur / Angular_resolution Dawes_limit	(4) $\theta '' = {11.6\over D} arcseconds$	0.91'' = 11.6/12.7 `Oeil nu = 1' = 60 ''`

Force Gravitationnelle / Gravitational_Force

(5)

$F = {G . m_1 . m_2 \over r^2}$

G = 6.67 . 10^{-11} ({Nm^2/ kg^2})

Spectre Electromagnétique / Electromagnetic_Spectrum
h: Planck's constant c: Speed of light

(6)

$E_{photon} = {h . c \over \lambda}$

c=299792458m/s \newline h=6.626069.10^34 J.s

Loi de Planck / Planck_Law `blackbody radiation only depends on the temperature`	(7) $\beta_\lambda(T) = {{1\over \pi}{ C_1\over \lambda^5}{1 \over {e^{C_2 \over \lambda T}-1}}}$
Approximatiton de Wien / Wien_Law	(8) ${({\lambda T \ll 1})} \Rightarrow {{1\over \pi}{ C_1\over \lambda^5}e^{-C_2 \over \lambda T}}}$	valable dans le spectre visible
Loi de Wien / Wien_Law `Blackbody radiation spectrum peak`	(9) ${({d\beta_\lambda \over d\lambda} = 0)} \Rightarrow \lambda _{max} = { 0.29 cm \over T}$	ex: Sun is 6000 K $\lambda_{max} = {0.29 \over 6000} = 480nm$ yellow-green
Loi de Stefan Boltzman / Stefan_Law `E0 = energy flux (W/m²)`	(10) ${{\int_0^\infty \beta_\lambda . d\lambda}} = E_0 = { \sigma . T^4}$	$\sigma = 5.67 . 10^{-8} W/m^2.K^4$
Luminosity `L = Total power radiated from an object (W)`	(11) $L = F . A = { 4 . \pi . R^2 . T^4}$	For a sphere (like stars), the area is given by: A = $4 \pi R^2$ )