astrophysics Flashcards
order of size space
moon/satellite- planet - star - solar system - galaxy - universe
satellites
orbit planets
natural - moon
artificial - International Space Station
planets
orbit stars
Mercury- Venus - Earth - Mars - Jupiter - Saturn - Uranus - Neptune
comets
orbit star in an elliptical orbit
consists of ice rock and dust
fastest when closest to star
when close to star has trail (ice melts)
what keep in orbit
gravuty
orbital velocity
v = 2 pi r/T
convert time and radius into units to match velocity or use own
life cycle of a low mass star
nebula > protostar > main sequence star > red giant > white dwarf
life cycle of a high mass star
nebula > protostar > main sequence star > red super giant > supernova > neutron star/black hole
nebula
cloud of dust and gas (H)
protostar
GPE > KE + heat
dust and gas forced together by gravity
main sequence
nuclear fusion of H > He when temp is high enough
stable - gravitational force balanced by radiation pressure due to heat
red giant / super giant
H starts to run out (no nuclear fusion)
core collapses
fusion of He > heavier elements
white dwarf
outer layers float away leaving small core (no nuclear fusion)
supernova explosion
heat from explosion fuses Fe > even heavier elements
neutron star
the very dense core left after a supernova
black hole
an object whose gravity is so strong that nothing not even light can escape
gravitational field strength
g measured in N/kg
hertz spring russel diagram
absolute magnitude of luminosity against temp.
hertz spring russel diagram temp.
colour determines surface temp.
blue - hot
red - cooler
hertz spring russel diagram absolute magnitude
how bright they appear to be if all at same distance away
affected by temp + size
bigger + hotter = brighter
- red giants are cool but big so bright
- white dwarfs are hot but small so not that bright
spectra
when we look at white light that has past through the prism it splits into colours (continuous spectrum)
absorption spectrum
when we look at light from stars and galaxies we see this
- brightest wavelength determines temp
- absorption lines - gas surrounding star absorbed diff wavelengths or colours and appear as dark lines
absorption spectra use
we can identify what elements exist in star
each element absorbs its own unique set of wavelengths
doppler effect
change in wavelength (or frequency) due to relative motion between the source of waves and observer
red shift
same pattern of lines moved towards red end of the spectrum
wavelength increased moving away
cause of redshift
the doppler effect
- can happen to any wave (sound or light)
- change in wavelength (or freq. ) due to relative motion between the source of waves and observer
blue shift
wavelength decreased - moving towards
velocity of moving source
change in wavelength/ wavelength = velocity / speed of light
speed of light
3 x 10^8 m/s
big bang theory
creation of the universe (space and time) universe began at a single hot dense point > expanded since big bang > cooled since big bang
evolution of universe
big bang > protons / electrons > atoms > stars > galaxies > life in earth
evidence of big bang theory
- red shift of light from distant galaxies
- CMBR
galaxies are moving away at speed - big explosion started this at some point
CMBR is left over energy from big explosion
red shift as evidence for big bang
hubble used redshift to calculate speed moving further away galaxy = moving faster
therefore universe is expanding
and at some point must’ve started at one point
CMBR as evidence for big bang
light released when atoms first formed should still exist all around
universe has been expanding so wavelength of light should redshift (to microwave)
CMBR was discovered to exist in every direction
