ASTA02H3 Lecture Notes - Lecture 2: Electromagnetic Spectrum, Black Body, Apparent Magnitude
Document Summary
Waves of light, including visible and non-visible light. Amount of energy passing the unit area in a unit time. Measure of total amount of energy released by a body per unit time m -> apparent magnitude. M = 6 vs m = -6 (-6 is considered bigger in terms of magnitude) Take a measure of it that is the absolute magnitude. A body that absorbs all electromagnetic radiation. Em radiation emitted by a black body in thermodynamic equilibrium. M = m m = 5log (d/10) *distance must be in pc* m 5log (d/10) = m. L = (4pir^2)sigma t^4 *sigma = 5. 67 x 10^-8 w/m^2r^4. T^4 l/4pir^4 -> t = 4square root l/4pir^4 or (l/4pir^2)^1/4. T of sun = 5800 k *t is in k* (wavelength) peak = 0. 29cm/ t. = 0. 00005 cm or 5 x 10^-7 m. R = 2. 59 ro = 2. 59 * 6. 7 x 10^8m.
