Translated material
Giants and dwarfs
Scientists have found a new way to detect small-mass exoplanets
The number of planets orbiting their stars outside the solar system is expected to increase significantly in the near future. By the end of June, 464 such planets had been discovered. A group of astronomers from Germany, Bulgaria and Poland, led by Grazian Maczewski from the University of Jena (Germany), discovered a new exoplanet using a completely new search technique.The accuracy of the technique is so high that it will make it possible to find very small planets that do not weigh more than the Earth. The new method for searching for distant planets is based on Transit Timing Variation (TTV). According to the magazine Monthly Notices of the Royal Astronomical Society, astronomers have already managed, using the development of scientists, to discover a planet 15 times heavier than Earth. It is located in the WASP-3 system, located in the constellation Lyra 700 light years from the Sun.
In astronomy, a transit is the passage of a planet in front of the star it orbits. Passing in front of her “parent”, she blocks part of his light for some time. At the moment, a number of planets have already been found using transit variations. The method is actively used in the work of the Kepler and COROT space telescopes, which are searching for planets comparable to the Earth.
The essence of searching for planets using the transit time variations method is as follows: if there are several small planets near a large planet, then the force of their gravity will act on the giant and cause deviations in the transit in front of its star, calculated using computer models. If there are no additional bodies in the system, then numerous transit observations should give the same results.
The new exoplanet was discovered while studying the transits of WASP-3b, a huge planet whose mass is 630 times the mass of Earth. The planet was found three years ago and makes a complete revolution around its star in 1.85 Earth days. To do this, astronomers used a telescope with a mirror with a diameter of 90 cm at the University of Jena Observatory and a 60-centimeter telescope at the National Astronomical Observatory of Rozhen (Bulgaria). Scientists have discovered periodic deviations in the transit time of WASP-3b, which can be explained by the presence of an additional planet in the system. The mass of this planet is 15 times the mass of the Earth and approximately equal to the mass of Uranus. In order to circle around its star, it needs 3.75 Earth days.
In accordance with international astronomical rules, the new planet was named WASP-3c. This is one of the lightest exoplanets known at the moment. WASP-3c is also the smallest planet orbiting a star heavier than our Sun.
For the first time, astronomers managed to find a new exoplanet using the method of temporary transit variations, by the way, the same indirect search method as other methods of searching for planets located outside our solar system. The discovery of a second planet in the WASP-3 system makes it very interesting for scientists. The new planet appears to be moving in an outer orbit that is elongated and twice as long as the larger planet's. This configuration is most likely the result of early evolution of the system.
The method of transit time variations seems very attractive because it is highly accurate when searching for small planets, the mass of which may be smaller than even the mass of our planet. For example, a planet the weight of Earth will impact a typical gas giant orbiting close to its star, resulting in deviations of up to one minute in the transit time of a large planet.
This deviation is large enough to be detected using relatively small telescopes with a mirror diameter of up to 1 m. Observations can then be continued with larger telescopes. For example, Gracian Maczewski is carefully studying WASP-3c using the Texas Hobby-Eberly Telescope with a mirror diameter of about 10 m.