When we analyze all the planets of the solar system we see that there are both inner planets and outer planets. However, there are various space missions dedicated to the search for planets outside the solar system. Planets that have been discovered beyond the boundaries of our solar zone are known as exoplanets.
In this article, we will tell you everything you need to know about exoplanets and the methods by which they are discovered.
What are exoplanets?
There are many projects that try to search for exoplanets outside the solar system. This term refers to planets that lie outside the solar system, although there is no official definition that meets specific characteristics. More than a decade ago, the International Astronomical Union (IAU) made some distinctions to better define the terms planet and a dwarf planet. When these new definitions were established, Pluto was no longer officially considered a planet and was called a dwarf planet.
Both concepts refer to celestial bodies that revolve around the Sun. The common characteristic that includes them is that they have enough mass that their own gravity can overcome the rigid body forces so that they acquire hydrostatic equilibrium. However, as mentioned earlier, the same is not true of the definition of an exoplanet. To date, there is no consensus on the common characteristics of planets that have been discovered outside the solar system.
For ease of use, it refers to exoplanets, as well as all planets outside the solar system. They are also known as exoplanets.
Once a consensus has to be established to define, collect and classify these planets, common characteristics need to be established. In this way, the IAU collected three characteristics that exoplanets should have. Let’s see what these three characteristics are:
- They represent a true mass object below the deuterium nuclear fusion limiting mass.
- Revolve around a star or stellar remnant.
- Represent a mass and/or size greater than what is used as a planet boundary in the solar system.
As expected, comparative characteristics between planets outside and inside the solar system are established. Similar characteristics should be looked for since all planets tend to revolve around a central star. In this way, “solar systems” are simultaneously formed to form what we know as galaxies. If we look at the dictionary of the Royal Academy of Spain, we find that the term exoplanet is not included.
The first exoplanet was discovered more than a quarter of a century ago. And it is that in 1992 several astronomers discovered a series of planets orbiting a star known as Leach. This star is special in that it emits radiation at very short irregular intervals. It can be said that this star functioned as a beacon.
A few years later, two scientific teams found the first exoplanet orbiting a Sun-like star. This discovery was quite important to the world of astronomy because it showed that planets exist outside the boundaries of our solar system. In addition, the existence of planets that could orbit stars similar to ours has been confirmed. That is, other solar systems may exist.
After that, with the improvement of technology, the cie society ntifica was able to observe thousands of exoplanets in various missions in search of new planets. The most famous is the Kepler telescope.
Methods of exoplanet search
Since these exoplanets cannot be physically detected, there are various methods of finding planets outside the solar system. Let’s see what the different methods are:
- Transit Method: Today this is one of the most important techniques. The purpose of this method is to measure the brightness emanating from the star. The passage of an exoplanet between the star king and Earth so that the brightness reaching us will periodically decrease. We can indirectly conclude that there is an extrusion planet in this region. This methodology has proven to be very successful and is the one most used in recent years.
- Astrometry: It is one of the branches of astronomy. He will be tasked more with analyzing the position and correct movement of the stars. Thanks to all the research done by astrometry, it is possible to detect exoplanets by trying to measure the small perturbations that the stars make on the stars they orbit. However, no extrasolar planets have been found using astrometry to date.
- Radial Velocity Tracking: This is a technique that measures how fast a star moves in a small orbit formed by the pull of an exoplanet. This star will move towards us and away from us until it completes its own orbit. We can calculate the velocity of the side of the line-of-sight star if we have an observer from the ground. This velocity is known as radial velocity. All of these small variations in velocity cause changes in the spectrum of the stars captured. That is, if we follow the radial velocity, we can detect a new exoplanet.
- Pulsar Chronometry: The first extrasolar planets orbited a pulsar. This pulsar is known as starlight. They emit radiation at irregular short intervals as if they were beacons. If an exoplanet orbits a star that has these characteristics, it can affect the beam of light directed at our planet. These features may lead us to the knowledge of a new exoplanet orbiting a pulsar.