What’s Outside Our Solar System: Observing Exoplanets

The Solar System

The System of Stars

The universe is made up of several stars, either binary systems or multiple systems. A binary system is where two astronomical bodies are close enough that their gravitational attraction causes them to orbit around each other. While a multiple star system consists of three or more stars. Almost half of the stars in the universe are in binary systems!

The Hertzsprung-Russell Diagram

Stars can be classed by their spectra (the elements they absorb) and their temperature. There are seven main types of stars classifying in order of decreasing temperature; O, B, A, F, G, K, and M. The Sun for example, belongs to class G, a yellow dwarf, in the main sequence phase.

The Hertzsprung-Russell Diagram

What’s an Exoplanet?

Planets in our solar system orbit around the sun. Exoplanets orbit around other stars in our galaxy. The only problem is that they’re hard to see because they’re usually hidden by the bright glare of their host stars.

The First Discovered Exoplanet System

Detecting Exoplanets

So how do we actually detect these exoplanets. Think about it, they’re light years away. Astronomers currently have two main methods of observation.

Radical Velocity Method

The radical velocity method is the first method to successfully detect exoplanets. It’s based on the observation of the oscillation or wavelength variation in the star’s spectral lines (a dark or bright line in an otherwise uniform spectrum, resulting from emission or absorption of light in a narrow range).

Transit Method

The transit method is based on the observation of the exoplanet-star eclipses seen by the astronomer. The orbital inclination of the planet and its relative radius in relation to its parent star can be observed during transit.

Combining Detection Methods

Combining the data collected from the transit method and the radical velocity method, the masses and rays of the exoplanet can then be obtained. Other physical parameters can also be derived from the combination of the two methods.

Detection Technology

One of the most developed areas of astrophysics is the discovery of exoplanets. However, discovery is difficult because the light sent from an exoplanet is considerably weak compared to its host star.

Earth Telescopes

Though exoplanet discovery is difficult, one of the most common detect methods is through the use of terrestrial telescopes.

Lick and Keck Telescope

Spatial Telescopes

On Earth, it’s impossible to detect exoplanets which are smaller than Earth due to Earth’s atmosphere as ground based telescopes cannot obtain more astronomical object waves. However, spatial telescopes are effective in the detection and characterization of exoplanets.

Kepler Mission by NASA

Instruments and Detections

There’s a bunch of noise that clouds the data collected by astronomers on exoplanets. Optical and interferometric technological devices are used to remove these obstacles that drive astronomers to false results during observations.


Characterizing Exoplanets

To understand the formation and evolution of planets, data from their host stars is helpful. The relationship between X-ray emission by a star’s corona, the age of the same star and the change of this relationship are requisite to reveal the following exoplanets’ history.

Dynamic Characterization

Spectral rays sent from astronomical objects hide their atmospheric compositions since the atmosphere characterization of an exoplanet is based on the studies of its host star too.

Chemical Composition

Atoms and molecules have been detected in exoplanets smaller than the size of Neptune! The composition, structure and evolution of planets that orbit a star depend on the star chemical compositions.

Research for Extraterrestrial Life

What does all of this mean? Can we live on an exoplanet similar to Earth? Well, not exactly, but some really interesting findings are coming out of exoplanet discovery.

The Future of Exoplanets

Water is still the main basis of life. Due to the presence of oxygen in the atmosphere of an exoplanet, it means life on such planets is not possible. The current priority is the detection of water and oxygen outside the solar system because of their roles as being the sources of life. Until then, we wait.



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