Stars Flashcards
(46 cards)
What is a meteroits
Bits of asteroid or bits of rock which make it through the journey of the earths atmosphere and the to the surface
Define a planet
An object with sufficient mass for their own gravity force to make them a spherical shape where no nuclear fusions occur and the object has cleared its orbit of other objects
What is a dwarf planet
Planets where the orbit has not been cleared of other objects
what are asteroids
objects which are too small or too uneven in shape to be planets with a near circular orbit around the sun
what are comets
small irregularly sized balls of rock,dust and ice
give the timeline for the evolution of a low mass star and give the size
Nebula, protostar, Main sequence star, Red giant, white dwarf, black dwarf
from 0.5- 10 solar masses
give the timeline for the evolution of high mass stars
Nebula, protostar, Main sequence, Red super Giant, supernova, Neutron star, black hole
what is nebula
gigantic clouds of dust and gas, over millions of years the gravitational attraction between the particles pulls them together to form clouds. As they come closer together the gravitational collapse accelerates and some regions become denser and pull in even more dust and gas. this energy is then converted to thermal energy
what happens after the gravitational energy converts into thermal energy in the nebula
a protostar is formed,
what is required in the protostar for a star to e formed
the temp and pressure must be high enough for the hydrogen nuclei in the protostar to overcome the electrostatic forces of repulsion and undergo nuclear fusion, producing helium producing a star
what happens in the main sequence star phase how is this stage different in larger stars
the star is in a stable equillibrium where the gravitational forces of the particles act to compress the star but are counteracted by the radiation pressure from the photons emitted in fusion and gas pressure from the nuclei
in larger stars they are hotter therfore this stage is shorter as they undergo faster fusion
what is the solar mass equal to
= 1.99 x 10^30 kg
explain what happens after the main stage of a low mass star
once the hydrogen supply is low the gravitational forces inwards overcome the radiation and gas pressures so the star collapses inwards and evolve into a red giant (cooler ) the core of the red giant is too cool for fusion to occur, but the pressure in the outer layers is great enough for fusion to occur.
what happens after the red giant phase for a low mass star
fusion occurs in the outer layers but not in the core, so the giant evolve into a hotter white dwarf as the outer shells drift off as planetary nebula , the core remains dense which has a very high temp
what happens in the white dwarf in low mass stars (electron degeneracy)
the photons which were produced leak out dissipating heat and the core starts collapsing however electron degeneracy prevents the core from collapsing completely. and as long as the mass of the core is less than 1.44 solar masses the white dwarf is stable
what is electron degeneracy
where 2 electrons can not exist in the same state
what happens after the amin stage for a high mass star
stars which are larger than 10 solar masses, after the main phase will have a high enough temp for helium fusion into heavier elements producing elements upto iron
why does fusion only happen upto iron in high mass stars after main stage
iron does not release energy therfore can not fuse further
what happens after iron is prod high mass star
the star becomes unstable and a type2 supernova occurs where there is a shockwave which ejects materials into outer space and the core collapses however elements hevier than iron can be formed in supernovas
what happens after the supernova
high mass stars
if the remaining core mass is larger than 1.44 solar masses protons and electrons combine to become neutrons producing an extremely small neutron star and if the remaining mass is more than 3 solar masses it will become a black hole where light can not escape
When does an electron get excited
When it is going from a lower energy level to a higher one
What happens when an electron moves towards the ground state
It gets de-excited and releases energy in the form of a photon with a specific wavelength
State the conditions for electron in energy levels
Electrons can only exist in one of a no. Of discreet levels ( energy level)
Electrons can not have an energy value in between 2 levels (discrete levels)
All electrons bound to the atom have -ve energy values as they would need to give energy to return to 0 ( to escape atom)
The ground state (the lowest energy level) is the most -ve value
