Astronomy final
Introduction: Searching for extra-solar planets is not a very easy task. Because most of the times we find them by not actually looking at them but by the effects they produce mainly on the star around which they are rotating. It is because planets look like just a dull spec of light through a telescope. The distance between us and a nearby planet is very large. In our scale model it will be like looking at a dust particle in Thunder Bay Ontario if we are sitting in Halifax with our telescope. That’s why astronomers have adopted various techniques to find extra-solar planets. In most of the techniques we focus on the star around which planets are rotating and by noticing the changes occurring in star we can decide whether that star has planet(s) or not. The following methods are used for that purpose.
1. Astrometry
2. Radial Velocity Method
3. Pulsar Timing
4. Transit Method
5. Gravitational Microlensing
Astrometry: This is the oldest method used to search extra-solar planets. This planet is basically used to find the mass of thee planet. This method is based on the gravitational effect of planet on its host star. As the planet rotates around its star, it applies gravitational force on the star and makes the star to move under the effect of its (planet) gravity. Thus, both the star and the planet revolve around a common center of mass also called center of gravity. Thus, the position of star always keeps on changing, which we can notice by using sensitive telescopes and thus by drawing 2D or sometimes by 3D graphs of position of star and measuring how the x and y intercepts are changing. How much the position is changed will decide the mass of planets. Massive the planet, grater will be the change in position.
This method is most useful in the absence of atmospheric distortion. That’s why telescopes like
1. Astrometry
2. Radial Velocity Method
3. Pulsar Timing
4. Transit Method
5. Gravitational Microlensing
Astrometry: This is the oldest method used to search extra-solar planets. This planet is basically used to find the mass of thee planet. This method is based on the gravitational effect of planet on its host star. As the planet rotates around its star, it applies gravitational force on the star and makes the star to move under the effect of its (planet) gravity. Thus, both the star and the planet revolve around a common center of mass also called center of gravity. Thus, the position of star always keeps on changing, which we can notice by using sensitive telescopes and thus by drawing 2D or sometimes by 3D graphs of position of star and measuring how the x and y intercepts are changing. How much the position is changed will decide the mass of planets. Massive the planet, grater will be the change in position.
This method is most useful in the absence of atmospheric distortion. That’s why telescopes like
References: http://en.wikipedia.org/wiki/Methods_of_detecting_extrasolar_planets http://www.cfa.harvard.edu/news/2007/pr200711.html http://en.wikipedia.org/wiki/OGLE-2005-BLG-390Lb http://www.space.com/scienceastronomy/070424_hab_exoplanet.html Discussion with Prof. Douglas Pitcairn (Professor of Sky and Planets) Saint Mary’s University Halifax, NS, Canada. http://www.cnes.fr/automne_modules_files/standard/public/p1403_9ef5e2e97d4ce878ede92d956cd5fcadtransit.JPG