#!/usr/bin/gnuplot # signal_sum_hvezda.plt # Signal a sum pri fotometrii hvezdy. # Miroslav Broz (miroslav.broz@email.cz), Dec 6th 2008 AU = 149.6e9 # m; astronomicka jednotka pc = 206260.*AU # m; parsek L_S = 3.84e26 # W; zarivy vykon Slunce L_star = 0.01*L_S # W; zarivy vykon hvezdy r = 500.*pc # m; vzdalenost hvezdy # zkouska pro Slunce: #L_star = 1.*L_S # W; zarivy vykon hvezdy #r = 10.*pc # m; vzdalenost hvezdy S = 4.*pi*r**2 print "L_star = ", L_star, " W" print "r = ", r, " m = ", r/1.e18, " 10^18 m" print "S = ", S, " m^2" nm = 1.e-9; lambda = 500.*nm # m; nanometr c = 299782458. # m/s; rychlost svetla h = 6.63e-34 # J*s; Planckova konstanta f = c/lambda; E_gamma = h*f; print "f = ", f, " Hz = ", f/1.e15, " 10^15 Hz" print "E_gamma = ", E_gamma, " J" n_star = L_star/E_gamma print "n_star = ", n_star, " kvant/s vyzaruje *" d = 1. # m; prumer dalekohledu S_d = pi*d**2/4. L_d = L_star/(4*pi*r**2) * S_d n_d = L_d/E_gamma n_pixel = n_d / 9.; print "S_d = ", S_d, " m^2" print "S_d/S = ", S_d/S print "L_d = ", L_d, " W" print "n_d = ", n_d, " kvant/s zachyti dalekohled" print "n_pixel = ", n_pixel, " kvant/s na 1 pixel" t_exp = 45. # s; expozicni doba n_gamma = n_pixel * t_exp print "\nn_gamma = ", n_gamma, " kvant celkem za t_exp = ", t_exp, " s" Q_n = 0.8 # ; kvantova ucinnost n_e_ = Q_n * n_gamma print "n_e_ = ", n_e_, " elektronu" eta = 1. # ADU/e-; ucinnost A/D prevodniku S_star = eta * n_e_ print "S_star = ", S_star N_star = sqrt(S_star) print "N_star = ", N_star S_sky = 2000. # ADU; signal od oblohy N_sky = sqrt(S_sky) print "N_sky = ", N_sky S_dark = 100. # ADU; temny proud N_dark = sqrt(S_dark) print "N_dark = ", N_dark N_readout = 15. # ADU; vycitaci sum N = sqrt(N_star**2 + N_sky**2 + N_dark**2 + N_readout**2) print "N = ", N, " (celkovy sum)" S_N = S_star/N print "S_star/N = ", S_N ######################################################################## m_S = -26.73 # mag; zdanliva VIZUALNI hvezdna velikost Slunce m = m_S - 2.5*log10((L_star/r**2) / (L_S/(1.*AU)**2)) print "\nm = ", m, " mag" M = m + 5 - 5*log10(r/pc) print "M = ", M, " mag (toto pro Slunce vychazi 4.84 mag OK!)" L_0 = 3.055e28 # W; zarivost objektu s M = 0 mag M = 0 - 2.5*log10(L_star/L_0) print "M = ", M, " mag (toto je BOLOMETRICKA magnituda, pro Slunce vychazi 4.75 mag OK!)\n" m_M = 5.*log10(r/pc) - 5. print "(m-M) = ", m_M, " mag" m = M + m_M print "m = ", m, " mag" ########################################################################