AST201H5 Chapter Notes - Chapter 11: Neutrino, Lead, Radiography
Document Summary
Diametre: multiplying the sun"s angle (0. 5 ), distance (1. 5x108km), we get a diameter of. 1. 4x106km (109xearth: volume = width x height x depth sphere volume is approximately = dia3. Volsun = (109earth)3 = 1. 6million earths: mass (using newton"s derivation of kepler"s 3rd law) = 2x1030kg (333,000 x mearth, average density = mass/vol = 1. 4g/cm3. About the same density as water made up mostly of hydrogen. Temperature: using it"s thermal radiation spectrum, we find tsun = 5800k, makes the sun so hot, it"s all gas. Composition: using an absorption spectrum, we find that the sun"s composition is primarily, by number**: 90% h, 9% he, 1% other elements. By mass: 70 % h, 28% he, 2% others. Stability of the sun: the sun maintains a constant size and energy output (important for nuclear fusion to take place) through: Gravitational equilibrium (or hydrostatic equilibrium): the balance between the outward push of internal gas pressure and the inward pull of gravity.
