Frame of Reference = A system of coordinates that enables the position of various objects to be specified/ that enables measurements to be made.
Galilean Transformation = transformations made under the assumptions that time measurements (and space measurements) are independent of the observer;
Astrophysics
Chadrasekhar Limit = mass after which a white dwarf does not form. Equivalent to 1.4 solar masses.
(The heavy mass causes the star collapse into itself to form a neutron star)
Openheimer-Volkoff Limit = a neutron star is stable up to this mass which is equivalent to 3 solar masses, beyond this point and it forms a blackhole.
Luminosity: the total energy emitted by the star per second.
Apparent Brightness: The incident power per unit area received on the surface of the Earth
Apparent Magnitude: A measure of how bright an object appears from Earth
(Good to know but not needed in answer: it is a comparative scale)
Absolute Magnitude: The apparent magnitude when observed at a distance of 10 parsecs
Alternatively: a measure of how bright the object appears from 10 parsecs away. (I recommend the first definition using apparent magnitude...easier to remember)
