Stars Flashcards
(57 cards)
more massive stars, due to greater gravity, are..?
squeezed into smaller, more densely packed objects than less massive stars
hottest, brightest and more massive stars
Blue stars
90% of the stairs
Main sequence stars
stars exceeding eight solar masses, with short life spans
High-Mass Stars
Stellar Evolution of Medium-mass (sun-like) stars
Nebular > protostar > main-sequence > red giant > planetary nebula > white dwarf
Red Giant Stage
begins when the hydrogen is consumed, leaving a helium-rich core > core no longer has the gas pressure that resist the inward pull of gravity > core contracts, temperature increase > expansion of the star > as the star expands, its surface cools (red) > eventually the star’s gravity stops expansion > gravity and gas pressure, again achieve balance > star enters a stable state, but is much larger > astonishing increase in temperature, converts helium into carbon and oxygen
largest white dwarfs = ?
least massive
smaller and more massive than white dwarfs
Neutron Stars
“average star”
Sun
radiates short pulses of radio energy named pulsar (pulsating radio source)
Neutron Stars
without fuel ->no balance between gas pressure and gravity > it collapses > enormous implosion resulting in a shock wave > this energetic shock wave blasts the star’s outer shell into space generating ..
SUPERNOVA
terminate in brilliant explosions (supernova)
*during supernova, these stars become millions of times brighter
High-mass stars
terminate in brilliant explosions (supernova)
*during supernova, these stars become millions of times brighter
High-mass stars
*much fainter and smaller than the main-sequence stars of the same temperature
*some are almost the same size of Earth
White Dwarfs
form if the core of a remaining star exceeds the three solar mass limit (neutrons can withstand the gravity)
Blackhole
90% of star-life
Main-sequence stage
some red giants alternately contract and expand
variable stars
Hertzsprung-Russell Diagram

Protostar Stage
gravitational contraction continues rapidly > core heats much faster > temperature: 10 million K > start to initiate nuclear fusion (hydrogen fusion) > will reach a point wherein inward pull of gravity will be balanced by temperature of hydrogen fusion
with masses ranging between 1/2 and eight times that of the Sun
Medium-Mass Stars
Stellar Evolution of Massive Stars
Nebula > protostar > main sequence (blue) > Red supergiants > supernova explosion > neutron star or blackhole
spirals around a “void”
accretion disk
main sequence = ?
active years