astrophysics Flashcards
forming sun
cloud of dust and gas collapsed (decreased vol increased pressure)
main sequence- materials collide until pres/temp high enough for hydrogen nuclei to start fusing and form helium then goes into stable period
nuclear fusion in sun
energy released by nf keeps core hot
stable sun
sun in main sequence phase
outward force of energy released by nuclear fusion= force of gravity pulling sun inwards
stable orbit
if speed changes,radius of orbit changes
radius decrease,speed increase as gravitational attraction increases (vice versa)
main sequence star
hydrogen nuclei fused together to form helium
releases energy as heat and light
red giant
eventually hydrogen runs out
star cools and expands becoming a red giant
star fuses together to form helium nuclei to release energy
white dwarf
as helium fuel runs out, outward forces reduce in size and star collapses inwards
causes temp increase
white dwarf formed, hot core of star
black dwarf
star completely cools and becomes a black dwarf
doesnt emit any light or heat
star life bigger than sun
red supergiant- nuclear fusion turns more mass into energy, expands into rspgt
supernova- largest stars explode into sn,produces elements heavier than iron and scatters them throughout universe
black hole or neutron star- left behind by sn
creation of elements
all stars- fuse hydrogen nuclei into helium in nuclear fusion
large stars- fuse hydrogen nuclei into lithium and other light materials
supernovae- produce enough energy for hydrogen nuclei to form elements heavier than iron
red shift
as an object moves away, wavelength of light emitted increases
gets redder as red has longest wavelength of visible colours
faster object is moving, longer wavelength, redder it appears
evidence for expanding universe
light from distant galaxies is red shifted
further the galaxy, greater the red shift
this means universe is expanding
big bang
universe began from small region
region ‘exploded’ and started expanding
expansion is still happening
