Feature astronomers Kolskogo open University (UK) planet WASP-104b is that its thick atmosphere absorbs almost all incoming light. The researchers compare it with coal and say that this is one of the darkest ever discovered planets.
The object belongs to the class of hot Jupiters, which is a huge gas giants, similar in mass to Jupiter but located very close to their stars, which have a very high temperature. Usually the orbital period of these planets is less than 10 days.
Representatives of this class are not uncommon, but they often exhibit features that make them very interesting for research. For example, one such feature is that hot Jupiters are much darker than normal planets.
Most of discovered to date are hot Jupiters, as a rule, absorb about 40 percent of the world. However, in 2008, astronomers discovered the planet WASP-12b, which were much darker than their counterparts. The scientists found that the planet is able to absorb at least 94 percent of incoming light. Discovered WASP-104b, in turn, was even darker. According to the calculations of astronomers, the object can absorb from 97 to 99 percent of the light its star.
“Among all the dark planets, which is written in the textbooks, I can easily write the WASP-104b in the top five of the dark. Not even in the top three,” says study leader, astrophysicist Kolskogo University Theo Mocnik.
One of the possible explanations for her “dark nature” may be the distance at which the planet is located from its star — a yellow dwarf star located around 466 light-years away in the constellation Leo. The distance between WASP-104b and her mother star is only about 4.3 million kilometers. Because of this, its orbital period rotation is only 1.77 day.
Like most hot Jupiters, WASP-104b has a tidal capture (one of its sides always faces the star). In other words, on one side of a planet of eternal day and the other eternal night. As a result, the day side of the planet so hot that it can’t form clouds, which would increase the reflectivity, and night — not ice may form because in General the temperature of the planet is very high.
Instead, WASP-104b has a very thick layer of hazy atmosphere, is likely to have a high content of atomic particles of sodium and potassium absorb light in the visible range of the spectrum and makes the planet very dark even on the light side, which is always illuminated by the star. On the night side of the planet clouds, very likely formed can, but because it never gets light, and to reflect these clouds, nothing.
Despite the fact that hot Jupiters are, as a rule, darker than usual planets to discover them is no more difficult than. They are all too far away for us to be able to see directly or to see the background much more bright stars, around which they are located.
The only available method of detecting these planets is to observe the change in the brightness of the stars, which usually decreases when a planet passes in front of the star and the observer. Such a search is called the transit method of detection, and it is a major and very effective way of finding new exoplanets, for example, space telescopes such as Kepler.
Because hot Jupiters are very large planets, they can be found using the Doppler method, which consists in spectrometric measurement of the radial velocity of the star. Star with a planetary system will move in its own small orbit in response to the attraction of the planet. This in turn will change the speed at which the star moves towards the Earth and away from it (that is, the change in radial velocity of the star relative to the Earth).
In addition, such planets cannot be called black as, say, coal, tar or the same Vantablack (the darkest material on Earth). Dark call them soon to determine their reflectivity, and not the radiated characteristics. Since these planets are usually very hot, they may have a deep bluish, purple or dull reddish glow.
At the moment the darkest ever discovered hot Jupiter is the planet TrES-2b that reflects just 0.1 percent of the light falling on it.