XV Международная студенческая научная конференция Студенческий научный форум - 2023

If we discard romanticism and seriously ask the question "What are exoplanets?", we can answer quite briefly. Exoplanets are planets located outside the Solar System. Looking at these planets, I came to a sad thought about the stereotypes of people who do not even know about the existence of such different and unusual worlds. But before getting to know them, we'll look at ways to find them.

Ways to study

It is impossible to notice an exoplanet by direct viewing through a telescope. Therefore, most exoplanets have been discovered using space telescopes. One of these is the Kepler telescope. It was launched into space back in 2009 and served until 2018. During all this time, he discovered more than a thousand exoplanets. But even such telescopes are not able to clearly see such distant objects.

Kepler discovered exoplanets by the transit method. The method is based on observing the passage of a planet against the background of its star, as a result of which the observer sees a decrease in the brightness of the star. More information is provided by spectral analysis.

Spectral analysis is a method of determining a chemical substance by its spectrum. It is based on the fact that the atoms of any chemical element give a spectrum that is not similar to the spectra of all other elements. Thus, astrophysicists will learn the chemical composition, temperature, speed of movement, pressure and much more.

The Doppler method is also used in the search for exoplanets. It is also based on observing the parent star. The planet, orbiting around it, swings it, and scientists observe a Doppler shift in the spectrum of the star. The method allows you to determine the density of the planet, the mass of the star, the period of rotation, etc.

The cherry on the top in the study of exoplanets is the James Webb telescope. Its construction began in 1997 and has been postponed for various reasons since 2007. Almost every year the launch was postponed. But still James Webb was launched on December 25, 2021. It is a "new generation" telescope, the largest telescope. 17 countries participated in its creation. The project cost was $10 billion. Now he is at the second Lagrange point, where the body can remain stationary due to the gravitational forces of the Earth and the Sun. Thus, the telescope has the least number of obstacles for studying previously discovered exoplanets.

The main types of exoplanets

What kind of exoplanets are there? One of the most common classes of exoplanets are hot Jupiters. These are gas planets located at a close distance from their home star. There are also super-earths. This term is understood as a planet with a mass of 5-10 Earth masses, and it does not depend on the suitability for life, but such planets are the most likely candidates for the existence of life. There are also orphan planets in space, such planets are not gravitationally bound to any star. They can appear by going out of orbit around their star as a result of some cataclysm. The most unusual exoplanets are pulsar planets – planets orbiting a pulsar.

Planet-diamond

The planet PSR J1719−1438 b orbits a pulsar. It emits a huge amount of radiation and enormous pressure. Only a planet consisting of dense matter is able to rotate in such conditions. Spectral analysis has shown that the exoplanet consists mainly of carbon. Therefore, scientists have concluded that this pulsar planet is completely diamond.

Scientists suggest that the planet was formed from a dying star. As she swelled and died, the pulsar began to actively absorb her substance. Thus, the star has lost more than 90% of its substance. It's a pity that it's 3,900 light-years away. But there are also exoplanets closer to us.

The planet where it rains glass

The planet HD 1897ZZ b belongs to the class of Hot Jupiters. This class is characterized by a close distance to the native star, a huge size, high temperature, and a composition mainly of gas. A year on this planet lasts 2 Earth days, because it is located 13 times closer than Mercury to the Sun. The planet is bright azure, but not because of the presence of water. The atmosphere of this planet is permeated with vitreous silicate particles, which melt due to extreme heat, and then fall as rain at an extremely high speed. It's a rain of glass. This miracle is located 63 light years away from us. By the standards of the universe, it's not far.

A planet with two suns

Kepler-16 b is an exoplanet near the binary star Kepler-16 AB in the constellation Cygnus. The object is located 245 light-years from Earth. Discovered in 2011, it became the first planet to orbit both stars simultaneously. Stars are similar to the Sun, although they have a smaller mass and are colder. However, with a double sunrise and sunset, the similarity of Kepler-16b and Tatooine (from "Star Wars") ends. Unlike the fictional stone world of Tatooine, the surface of which was a hot desert. Kepler-16b is a gas giant where cold prevails: the average temperature at the boundary of the planet's atmosphere does not exceed 73 degrees Celsius below zero, although both stars are quite close.

Worlds with possible life

If you are looking specifically for a planet suitable for life, then you should pay attention to the habitable zones (zones with the most favorable conditions for the origin and safe evolution of life). There are two of them: the galactic and the life belt of a particular star. Due to cosmic radiation and supernova outbreaks, most of our galaxy is not hospitable to life, so the galactic habitable zone is located where there is practically no activity. The belt of life around a star is determined by its luminosity and has a greater effect on the temperature of the planets.

The most common and suitable for the presence of life are red dwarfs. Due to the low rate of hydrogen combustion, red dwarfs have a very long service life, and they cannot turn into red giants. Over time, they gradually shrink and heat up more and more, until they use up the entire supply of hydrogen fuel and gradually turn into blue dwarfs.

Scientists have found super-earths most often when searching for exoplanets. Super–Earth is a common class of planets whose mass exceeds the mass of the Earth, but does not exceed the mass of Neptune. Such a planet is Kepler-452 b. It is located 1,402 light-years away from us. Its age is estimated at about 6 billion years and is located in a zone suitable for life. The mass of Kepler – 452 b is 5 times larger than Earth, and its gravitational force exceeds ours by about two times. Kepler – 452 b receives about the same amount of energy from its star as the Earth receives from the Sun, so photosynthesis is possible here. Geologists believe that there are even active volcanoes on the surface of Kepler – 452 b. It was named "Earth 2.0" because of its similarity to Earth.

But there is still a contender for a planet with the presence of life, this is Gliese 581 c. It is 20 light-years from Earth, about 5 times more massive than Earth. The exoplanet was discovered by the Doppler method, so there are only assumptions about its composition and properties, but it is known that it is located in the life belt. There is a possibility that the planet, with its mass, has a powerful atmosphere with a high content of methane and carbon dioxide and the temperature on the surface is much higher (up to +100 ° C) due to the greenhouse effect, as on Venus. The spectral analysis method could help in the search for traces of water vapor in the planetary atmosphere, but only if Gliese 581 c passes directly along the line of sight between its star and our planet, which is not currently established.

The TRAPPIST-1 system has 7 planets. All of them consist mainly of rocks, and some of them may even have more water than on Earth. TRAPPIST-1: d, e and f are in the habitable zone. The measured densities combined with models of the composition of the planets lead to the conclusion that the surfaces of the seven planets of the TRAPPIST-1 system are not just a bare stone desert. Apparently, they contain a significant amount of volatile substances, probably water, the amount of which in some of them reaches 5% of the mass of the planet. For example, on Earth water is only about 0.02% of its mass.

TRAPPIST-1b and c are the systems closest to the central star of the planet, most likely have a stony core and are surrounded by much denser atmospheres than Earth. But TRAPPIST-1d is the lightest: its mass is only about 30% of the earth's, and scientists doubt that it can have a noticeable atmosphere, oceans or ice cover.

Astronomers were surprised to find that TRAPPIST-1e is the only one of all the planets in the system whose density is slightly higher than that of Earth. This may mean that it may have a denser iron core, that it is not necessarily surrounded by a dense atmosphere, that there are no oceans or ice sheets on it. Mysteriously, TRAPPIST-1e turns out to be much more "stony" than all the other planets in the system. In terms of size, density and the amount of energy it receives from its parent star, this planet is more like Earth than any other.

TRAPPIST-1f, TRAPPIST-1g and TRAPPIST-1h are so far from the central star that the water on their surface should freeze. If they have atmospheres, they are unlikely to contain heavy molecules that the earth's atmosphere is rich in, such as carbon dioxide.

For a long time, exoplanets existed only in theory and science fiction. However, in the last two decades, astronomers have successfully developed methods of indirect detection and discovered more than 4,000 exoplanets. Many of them are different from the planets of our Solar system. There are incandescent planets on which life is impossible, there are planets with an unusual composition, but are there planets with another form of life? Scientists can't say for sure yet, because it's very difficult to study such distant objects. It is possible that very soon humanity will find a new civilization. Almost a year ago, the long-awaited James Webb telescope was launched, which has just begun its journey in studying the worlds discovered by its predecessors. Already on July 12, 2022, he discovered water on the gas giant WASP-96 b. And this is just the beginning.

Sources:

https://v-kosmose.com/

https://www.nasa.gov/

https://new-science.ru/

https://factsite.ru/

https://mediacratia.ru/

https://cafe-sheriff.ru/galaktiki

https://in-space.ru

https://myvera.ru/stars/3-2a

https://www.iskroline.ru/analysis

https://aboutspacejornal.net

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