Chapter 11, Problem 48A

As of 2007 more than 225 planets outside our solar system have been found (including an Earthlike one, not too hot and not too cold, likely with liquid water, orbiting about the star Gliese 581). Most of these planets were discovered by tiny wobbles of their parent stars. Why do stellar wobbles indicate the presence of planets?

To determine

To Explain: Stellar wobbles indicate the presence of planet.

Explanation of Solution

Introduction:

The wobble method is also known as doppler spectroscopy. It is indirect method use for finding the brown dwarfs and extra solar planet using information about radial velocity with the help of doppler shift in the spectrum of the planet.

In the solar system, all the planets are orbiting around sun due to the gravitational force. According to the general theory of relativity, heavy objects like planet and stars can deform the space time curvature around them so other nearby planets will feel a pull towards them and they will start orbiting around them.

In the given situation, there is a deformation of space time curve of planet which causes the radial velocity of the star to change and therefore, there is a shift in the frequency of start light. The detection of the doppler shift implies the presence of extra-solar planets.

Another advantage of wobble method is that the distance of planet from earth can also be calculated using Kepler's third law.