exoplanets

How is an exoplanet detected?

Radial speed

In this method, an attempt is made to detect the small oscillations of a star caused by the gravitational influence of a planet orbiting it; Because these oscillations make the star rotate around a common center of gravity, this can be detected through spectral analysis, measuring changes in the lines of the spectrum as the star moves away (redshift) or closer to us (redshift). to blue). It is the most effective method to discover exoplanets.

Astrometry

The astrometric method, which is related to positional astronomy, consists of recording and measuring the small changes in position that the star undergoes, as an oscillation, due to the gravitational influence of a planet orbiting it. However, such positional variations are tiny and have not been able to be measured accurately, so no results have been obtained with this method, and several "candidates" have been disproved. One famous one was a supposed planet around Barnard's star.

Transit

This system is based on making precise observations of the star's luminosity and recording small variations in its intensity as a planet "transits" it. The transit method is also useful for determining the planet's atmospheric composition. Several exoplanets close to their central star have been discovered using this method.

Gravitational microlensing

This method has to do with an action produced by both the gravitational influence of the planet and its central star. As long as they are properly aligned, this influence helps create a particular effect by focusing the light of a distant star (as seen through a lens), also aligned with the exoplanet and its star. Its complexity lies in the fact that such tentative exoplanets require a complementary analysis with one of the other methods.

Disturbance due to dust discs

This system is based on the fact that certain young stars have dust disks around them, called circumstellar disks, which are used to detect the presence of exoplanets; this is because, if an irregularity is discovered in the distribution of material in the disk, this would indicate the presence of a body passing through this gaseous zone, and forming a "hole" in it, which is where the exoplanet advances in its orbit. A known case using this method was an exoplanet around the star Fomalhaut, in the constellation Piscis Austrinus.