Chapter 16, Problem 1Q

To determine

The meaning of the luminosity of the Sun.

Explanation of Solution

Introduction:

The Sun is the largest and the only star in our solar system. It is composed of gases majorly Hydrogen and Helium. The radius of the sun is $695500\text{ km}$ and its surface temperature is 5800 K. The luminosity of the Sun is $3.828\times {10}^{26} \text{W}$.

The total energy released per unit time by the Sun is known as luminosity of the Sun. The SI unit of luminosity is Watts or Joules per second. The luminosity of the Sun is $3.828\times {10}^{26} \text{W}$ which is also written as $1L_{\odot }$ (1 solar luminosity). The luminosity of other stars and galaxies is referred in terms of solar luminosity. For example, the luminosity of the brightest star in our sky, Sirius is $25.4L_{\odot }$. This means, Sirius radiates 25.4 times the totalenergy emitted per unit time. Luminosity depends on the size and temperature of the object.