Ast 4 Lecture 11 Notes
1 The Sun
The Sun
•The Sun is a star
•A star is a glowing ball of hot gas held together by its own gravity and
sustains nuclear fusion in its core
•By studying the Sun we can learn about stars in general
The Sun
Some properties of the Sun
•Radius of the Sun is about 700,000 km (∼100 R⊕)
•Mass of the Sun is 1.99 ×1030 kg (∼3×105M⊕)
•The equator rotates faster than latitudes nears the poles
•Surface temperature of 5800 K
2 Structure of the Sun
2.1 Surface Layers
The Photosphere
The Photosphere
•Layer of the Sun we see
•500 km thick
•Temperature: 5800 K
•Density: 2 ×10−4kg/m3
The Chromosphere
