Astrophysics Answer Difficulties
Describe how the parallax angle is measured
– Take image of the star in JANUARY and JULY
– Measure distance it appears to have moved
– Measure distance it appears to have moved
State why the method of parallax can only be used for stars at distances less than a few hundred parsecond from Earth
Absorption and scattering of light in the atmosphere
Stages of evolution of a main sequence star that has a mass greater than 8SM
– Red super giant
– Supernova
– Black hole
– Supernova
– Black hole
Describe how cosmic wave background (CMB) radiation provides evidence for the expanding universe
– CMB isotropic (looks same in all directions)
– Provides evidence of high temperature early universe that cooled as it expanded
– Provides evidence of high temperature early universe that cooled as it expanded
Explain why Hubble’s law is not used to measure distances to nearby stars or nearby galaxies
There exist more accurate techniques
i.e Cepheid variables
i.e Cepheid variables
Difference between elliptical galaxies and Milky Way
Milky Way is a spiral galaxy vs elliptical galaxy and contains more gas and dust
Cosmic scale factor
A measure of relative expansion of the universe. Time-dependent function that describes how the scale of space changes in time. Sets a scale, or size, to the universe.
Hubble parameter, H
A measure of rate at which space in the universe expands. Hubble parameter changes over time, by convention H0 is used to indicate its value today
Gravitationally bound system
A system in which local gravity has to be considered in addition to the expansion of the universe to describe motions within that system