Week 2 Multi-Wavelength Night Sky, Effects of Dust & Blackbody radiation Flashcards
give 3 general observations about the optical night sky
starfield dominates the detectable output
central bulge is obscured
some light comes from hot gas
give 2 general observations about the infrared night sky
less extinction in comparison to optical
cooler objects emit longer wavelength radiation
give 2 general observations about microwave night sky
CMBR is prevalent in background
most emission comes from thermal dust/gas
give 2 general observations about the radio night sky
emission not dependent on stars
most emission comes from B field
give 3 general observations about the X-ray night sky
general comes from supernova emission
has two obvious points source- AGN and Neutron stars
Extinction is present
give 3 general observations about gamma-ray night sky
no extinction present
two point sources of black hole and neutron stars
general emission resultant of annihilation reactions
what causes extinction
dust between a source and observer absorbing radiation
describe what happens to long and short wavelength radiation passing through dust
both becomes less intense however shorter wavelength is more likely to be scattered out of line of sight
what does extinction depend on
grain size
describe what extinction takes place for small, comparable and large grains
small - rayleigh scattering
comparable - mie scattering
large - extinction is independent of wavelength
what is true of thermal radiation spectrum
it is only temperature dependent
what does Kirchoffs law state
source function of a material in thermal eqm is equal to Planck function
how do you convert from wavelength Planck function to frequency Planck function
differentials
