Astrophysics HL 10.2, 10.5

10.2 Stellar radiation and stellar typesAssesment statements  - State that fusion is the main energy soure of stars - Explain that, in a stable star (for example, our Sun), there is an equilibrium    between radiation pressure and gravitational pressure   Energy source of the stars   Proton-proton chain   Stable stars

10.5Stellar distances Assesment statements - Define the parsec- Describe the stellar parallax method of determining the distance to a star  - Explain why the method of stellar parallax is limited to measuring stellar distances less than several hundred parsecs- Solve problems involving stellar parallax Stellar parallax The parsec The parsec is defined as the angle subtended at the star.If the distance to a star is 1 pc, the angle subtended, theta will be 1 second.This makes calculations much easier since the distance in pc is simply 1/the angle in seconds- Arc secondsOne degree can be split up into 60 arc minutes and each arc minute into 60 arc seconds, so there are 3600 arc seconds in one degree.In radians 1 arc second is therefore (1/3600) x (2pi/360)Spectroscopic parallax Cepheid variables

New Page