MOSCOW, December 3, Tatiana PichuginaAstronomers have confirmed that there are silicate clouds on exoplanets. One of the recent discoveries is related to the hot Jupiter WASP-107b, nicknamed “fluffy” due to the characteristics of its atmosphere. What worlds look like where refractory minerals evaporate are in the material .
Silicate cloud hypothesis
On Earth, clouds arise from water vapor evaporating from the surface. Jupiter is shrouded in a gaseous shell, inside of which there is a layer of ammonia fog and ammonium hydrosulfide. The clouds on Venus are made of droplets of sulfuric acid. And outside the solar system there are planets with clouds of sand and metal.
In 1995, Swiss astronomers discovered the first exoplanet, close in mass to Jupiter, but located very close to its star. This was surprising, because in the solar system the star has small rocky planets, and the gas giants are very far away.
The planet orbits the Sun-like star 51 Pegasi, fifty light years away. She was designated 51 Pegasus b and nicknamed Bellerophon in honor of the ancient Greek hero who bridled the winged horse. It soon became clear that this was a new class of exoplanets, comparable in mass and size to Jupiter. Due to their proximity to the star, they are extremely hot, which is why they are called hot Jupiters. The most amazing thing is that they have an atmosphere.
At workIn 2000, scientists from the United States modeled the atmosphere of 51 Pegasi b based on calculated photometric data. According to their assumption, the temperature in the interior and on the surface is very high, approximately 1200 Kelvin. Even silicates from the mantle evaporate, but in the atmosphere they condense, forming a cloud layer of a suspension of microsand grains of minerals such as enstatite (MgSiO3). » media-type=»photo» data-crop-ratio=»0.62890625″ data-crop-width=»600″ data-crop-height=»377″ data-source-sid=»not_rian_photo» title=»This is how the artist presented imagine the giant planet 51 Pegasi b» class=»lazyload» width=»1920″ height=»1208″ decoding=»async» />
Anomalous brown dwarfs
Another unusual type of cosmic body is brown dwarfs. They were supposed to become stars, but due to their low mass they never flared up, turning into something similar to gas giants like Jupiter.
Anomalies in the data of the Spitzer telescope, which observed brown dwarfs in 2003-2009 , have long bothered astronomers. It turned out that in the atmosphere of some there were cloud layers of silicates. Recently, scientists from Canada analyzedresults, selected a hundred objects and determined their temperature: 1300-2000 Kelvin. Under such conditions, silicate clouds actually form.
Showers of titanium drops
This was confirmed by observations from the James Webb Telescope. The University of Arizona studiedspectra of the exoplanet VHS 1256 b, which revolves around a binary system with a period of ten thousand years in an orbit four times more distant than Pluto from the Sun.
The atmosphere there is constantly seething and mixing. In the depths, where the temperature reaches 830 degrees Celsius, clouds of silicate particles form. Their small fraction looks like haze, the large fraction looks more like sand. Due to their lower gravity than brown dwarfs, silicate clouds are located at a higher altitude, which makes them convenient for study.
In 2017 in the constellation Virgo, about two hundred light years away, the exoplanet WASP-107b was discovered. Orbits a slightly cooler and less massive star than the Sun. It is close in mass to Neptune, but with a much larger radius. Such worlds are called super-Neptunes.
Overall, the planet's density is very low, and the core turned out to be even less massive than expected. This does not allow the gas shell to be firmly held, and it is gradually blown away by the stellar wind — a trail trails behind the planet.
The atmosphere of WASP-107b is very large and rarefied, which is why it is called “fluffy”, “puffy”. Clearly visible through a telescope. As a result, European scientists determinedcompound. As it turned out, in addition to water vapor and sulfur dioxide, there are silicates that form clouds in the upper layers.
Planet LTT9779b has an even more exotic atmosphere. This is installedrecently using the Cheops Space Telescope. This celestial body reflects up to 80 percent of the light of its star (analogue of the Sun), that is, it is very bright. Planets are usually dim. Exceptions are rare. In the Solar System, these are Venus and Jupiter's icy satellite Enceladus.
LTT9779b is located very close to the star, at 2100 degrees during the day. Such objects are called superhot Neptunes. They should have no atmosphere at all: everything that evaporates from the surface is carried away by the stellar wind. However, LTT9779b is shrouded in heavy clouds of silicates, raining titanium onto the surface. As scientists explain, the planet is so hot that the gas shell is oversaturated with metal vapors 400 times stronger than that of the Sun. This allows metal clouds to be retained, and the abundance of silicates provides exceptional brightness.
Свежие комментарии