ASTROPHYSICS Flashcards
Red giant
A giant star with a relatively low surface temperature. That fuses helium nuclei in its core to form carbon
Nebula
A cloud of gas or dust in interstellar space
White dwarf
High surface temperature and low luminosity very small radius so small surface area remnant of a low mass star
Black dwarf
The theoretical end point of the cycle of a low - mass star
Red supergiant
Very hot, massive, luminous star with a short life span. iron is the heaviest element produced in the core as it has the highest binding energy per nucleon and cannot be fused together
Supernova
The explosion that occurs when a massive star’s core no longer undergoes fusion and the core collapses under gravity and the outer layers explode in a supernova
Neutron star
A dense ball of neutrons that remains at the core of a star after a supernova explosion. A star’s core becomes a neutron star if its between 1.4 -2.5 solar masses.
Pulsar
A rotating neutron star that emits energy in the form of radio waves at regular intervals
Black hole
A remnant of a massive star formed when its matter collapses to a point (singularity). A star’s core only becomes a black hole if its is more than 2.5 solar masses
Binary star
A system of two stars orbiting around their common centre of gravity
Black body
An object that is a perfect emitter and absorber of radiation, a black body absorbs all wavelengths that fall upon it and radiates all wavelength, the spectrum of wavelengths emitted only depends on its temperature.
Black body radiation
The radiation emitted from an object due to its temperature.
Hertzsprung Russell diagram
Logarithmic scaled graph of luminosity of stars against their surface temperature, on the temperature scale at each interval temperature halves and high temperatures are on the left
Stefan Boltzmann law
L= 4pi sigma r^2 T^4
where:
L= Luminosity
r= radius of star
T= temperature of star
Boltzmann constant,K
Relates the average energy of a molecule to its absolute temperature
Wien’s law
lambda peak x T= 2.898 x 10^-3 mk
Emission spectra
Characteristic colours (frequencies) of light given out by an element when electrons are excited.