Astronomy & space · University
Stellar structure and main-sequence scaling · revision notes
A hydrostatic star balances inward gravity with an outward pressure gradient. Equilibrium does not mean pressure is uniform.
Key ideas and conditions
Balance
A hydrostatic star balances inward gravity with an outward pressure gradient. Equilibrium does not mean pressure is uniform.
Energy
Main-sequence stars obtain their sustained energy from hydrogen fusion. The details and lifetime depend strongly on mass and composition.
Temperature and size
A blackbody approximation gives L=4πR²σT⁴. The model connects radius and effective temperature with total radiated power.
HR diagram
An H-R diagram relates luminosity to temperature or related observational proxies. A star's location helps constrain its evolutionary state with model assumptions.
Explain without looking
- A blackbody star has radius 2 times and temperature 1/2 times a reference. Find its luminosity ratio.
- Why must a blackbody scaling exercise not be treated as a complete stellar atmosphere model?
Further reading and review references
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