the 3rd celebration of knowledge Flashcards
what is the evolution of a low mass star?
protostar, main sequence star, red giant, helium burning star, double shell burning red giant star, planetary nebula, white dwarf
what is the evolution of a high mass star?
protostar, blue main sequence star, red super-giant, helium burning super-giant, multiple shell burning super giant, supernova, neutron star or black hole
what is a white dwarf?
the core of the former star
how does a white dwarf support itself?
since a white dwarf does not produce any energy via fusion, it cannot support itself against gravitational collapse via thermal pressure. the gas in the core is super-compressed by gravity such that it forms a degenerate gas where nuclei form a lattice and their electrons occupy their lowest energies
what is the relationship between mass and size of white dwarfs?
inversely proportionate (higher mass = smaller size)
what is a black dwarf?
when a white dwarf is isolated, it will eventually reach a point where it no longer emits substantial heat/light
do any black dwarfs actually exist?
no because the universe is not yet old enough
what is the limit to the mass of a white dwarf
1.4 solar mass
what happens when a white dwarf exceeds the white dwarf mass limit?
degeneracy pressure will fail and the white dwarf will undergo gravitational collapse, thus causing a white dwarf supernova (type I supernova)
what is a white dwarf nova
when i white dwarf is near a binary star system, the hydrogen gases of the donar star split into the white dwarf, creating a hydrogen based shell around the star. as the gas builds up, the temperature and pressure of the hydrogen begins to heat up the white dwarf to where it can start fusion again. the hydrogen ignites and the nova is created
can a nova happen more than once?
yes, a recurring nova can happen many times on a semi-regular basis (every 15-25 years)
what happens after a white dwarf supernova?
nothing. it completely destroys itself and everything around it, including the donar star
what are the differences between the types of supernovae?
type I: due to the explosion of a white dwarf star
type II: due to the core-collapse of a massive star
why are all pulsars neutron stars, but not all neutron stars pulsars?
because pulsars are only the stars that “flash” when the stars axis are pointed towards earth, those stars that don’t have axes that are aligned with earth’s view, they don’t pulse to us
what is a pulsar?
when the pulsar’s rotational axis are misaligned from the magnetic field
