Astrophysics Terminology HL Flashcards
Jean’s mass
method to discover if an interstellar cloud of gas in space will collapse and form stars.
If the mass of the cloud is > Jean’s mass – will collapse and form a star
If the mass of the cloud is < Jean’s mass – will not collapse or form a star
how does nuclear fusion work for stars like the sun? Describe the stages through chemical equations
proton-proton chain.
1) hydrogen-1 + hydrogen-1 –> hydrogen-2 + positron+neutrino
2) hydrogen-1 + hydrogen-2 –> helium-3 + gamma-ray photon
3) helium-3 + helium-3 –> helium-4 + hydrogen-1 + hydrogen-1
how does nuclear fusion work for bigger stars? Describe the stages through chemical equations
CNO process
1) hydrogen-1 + carbon-12 –> nitrogen-13 + gamma ray photon
2) nitrogen-13 –> carbon-13 + positron + neutrino
3) hydrogen-1 + carbon-13 –> nitrogen-14 + gamma ray photon
4) nitrogen-14 + hydrogen-1 –> oxygen-15 + gamma ray photon
5) oxygen-15 –> nitrogen-15 + positron + neutrino
6) hydrogen-1 + nitrogen-15 –> carbon-12 + helium-4
what is the nuclear fusion that occurs after the main sequence
1) helium-4 + helium-4 –> beryllium-8
2) helium-4 + beryllium-8 –> carbon-12
3) helium-4 + carbon-12 –> oxygen-16
nucleosynthesis
production of different nuclides by fusion
s-process
slow neutron capture to create heavy nuclides, has time to decay before capturing a neutron
r-process
rapid neutron capture to create heavy isotopes
supernovae
events in space that often appear as extremely bright stars
type 1 supernovae
event when material from a star falls into a white dwarf. A white dwarf gains too much mass from a red giant star in a binary star system – collapsing and exploding. New generations of stars may form afterward. Utilized as a standard candle since it always has the same peak of luminosity. Luminosity is brighter than type 2 but falls sharply. Does not have hydrogen lines in their spectra
type 2 supernovae
event when massive stars reach the end of their life cycle. A star’s core collapses due to gravity when it reaches critical mass (Chandrasekhar limit) and implodes producing neutrons and neutrinos. This produces a shock wave causing the explosion of a supernova. Not used as a standard candle since it has different peaks of luminosity. Luminosity is less than type 1 but falls of gently. Has hydrogen lines in its spectra
cosmological principle
that the universe is homogeneous and isotropic (the same and uniform) — that it has no edge and no center
critical density
the density that determines the shape of the universe
density < critical density – universe is open and infinite
density > critical density – universe is closed and finite
density = critical density – universe is flat expanding at a decreasing rate
MACHOS
Massive compact halo objects – a nature of dark matter theory. Black holes and neutron stars produce dark matter which could be too distant for luminous objects to detect easily
WIMPS
weakly interacting massive particles – a nature of dark matter theory. Subatomic particles that interact weakly with ordinary matter, possibly making up dark matter
Neutrinos – a nature of dark matter theory
that neutrinos with very small masses contribute to dark matter
