NATS 1740 Lecture Notes - Lecture 5: Cecilia Payne-Gaposchkin, Doppler Effect, Photosphere

• School: York University
• Department: Natural Science
• Course: NATS 1740
• Professor: Tatiana Paulin

Document Summary

Basic properties of the sun: distance -> 150 million km, diameter -> 109x diameter of earth, mass -> 333,000x mass of earth, density (mass per volume) -> a bit denser than water. Temperature: a measure of the average speed of the atoms and molecules of material. Heat: total energy stored in a material. Astronomers express temperatures in units of kelvin ( 0 k = -273 degrees celsius = absolute zero ) Absolute zero: the theoretical lowest possible temperature at which a material contains no extractable heat energy. Blackbody radiation: radiation emmitted by an opaque object. Wiens law: the hoter an object is, the shorter the wavelength is of its maximum intensity. Stefan-boltzmann law: hotter objects emit more energy than cooler objects of the same size. Wavelength of maximum intensity: the wavelength at which a perfect radiotor emits the maximumm amount of energy, depends only on the objects temperature.