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These planets are distinguished not only by the surface temperature, which is not very favorable for their life, but also by the exotic composition of the atmosphere. Exoticism is such that Earthlings would even lack the imagination to invent it ourselves, if the observational data doesn’t show: alumina clouds and molten titanium rain.
And more recently, a group of scientists created such a hot “star map” of Jupiter, looking at what kind of clouds and atmospheres we would see in each of them if we got close enough.
Exoticism is such that Earthlings would even lack the imagination to invent it ourselves, if the observational data doesn’t show: alumina clouds and molten titanium rain.
All hot jupiters have some common characteristics, but there are some important differences. And those differences may determine what our scientific instruments will see in the atmospheres of these planets, especially in the coming years, when even more powerful tools for observing exoplanets will be brought into space.
The upper mass limit for hot Jupiter is approximately 13.6 for our Jupiter mass. If the mass were a little higher, the deuterium would start connecting on these planets and they would become stars, brown dwarfs. The period of these planets (that is, their year), according to observation data, varies from 1.2 to 111 Earth days. The orbits are almost perfectly circular, with minimal eccentricity.
The density of many hot Jupiters is relatively low, and these planets are “flooded” with their star (that is, like the Moon, they do not revolve around their axis, but because such planets revolve only around their star, they do not have day or night changes – the same side is always lit or dark). Hot jupiters are usually found around Type F and G stars. They are less common among Type K stars. Such planets are rarely found in red dwarfs.
One of the reasons that scientists have recorded so many hot Jupiters is their ease of discovery. When these planets fly between their star and the observer (us, or more specifically, the Kepler telescope), they darken their own starlight much more than smaller planets. And because its orbital period is usually very short, the probability of noticing such a planet when you look at any star also increases considerably.
Because hot Jupiters are so easy to find and so convenient candidates for observing atmospheres with future telescopes, a group of astronomers has compiled their constellation. This atlas is essentially a model that describes a guide to the different types of atmospheres and clouds found on different hot Jupiters.
This group of astronomers included scientists from Canada, the United States, and the United Kingdom. The study was led by Peter Gao, a postdoctoral researcher at the University of California, Berkeley. The study, titled “Aerosol Composition of Hot Giant Exoplanets Dominated by Silicates and Hydrocarbon Gases,” was published in the journal Nature Astronomy.
The main objective of this work was to catalog all known types of Jupiter’s hot atmospheres.
As their own authors have argued in their final paper, “Aerosols are often found in exoplanetary atmospheres over a wide spectrum of temperatures, masses, and ages. These aerosols strongly affect the observation data received, which is reflected or emitted from the surfaces of the observed planets, and interferes with our understanding of the thermal structure and chemical composition of the planets. “
Understanding the effects of hot Jupiter atmospheric aerosols will give astronomers the advantage of observing such atmospheres in the future.
“Knowing the dominant aerosol formulations would facilitate interpretation of exoplanet observation data and gain a theoretical understanding of their atmospheres,” the atlas said.
This work is also important for astronomers outside the solar system, who, for example, analyze “cold” gas giants like the real Jupiter, Saturn, uranium or Neptune, as well as the planets of these planets, like Titan, which is surrounded by thick, cloudy atmosphere.
According to the researchers, a type of cloud in gas giant atmospheres is dominant regardless of whether those gas giants are hot or cold jupiters. These are “liquid or solid drops of silicon and oxygen that resemble molten quartz or molten sand.”
Study author P. Gao stated in a press release that “those clouds, which can exist in such hot atmospheres, wouldn’t even be called clouds in the solar system.”
“There were models that predicted different atmospheric compositions, but the goal of this study was to assess which of these components are really important and to compare these models with the data already available,” said the study leader.
The atmospheres of exoplanets (and everything related to exoplanets in general) are currently a very popular topic in astronomy. It has been popular for the past 10 years. Astronomers can explore these atmospheres because the starlight that penetrates and reaches them reveals certain details about the composition of those atmospheres.
For example, in 2019, scientists discovered water vapor in the atmosphere of an exoplanet. And maybe even rain. And in 2020, scientists were able to see the cast iron rain on the “night” side of a flooded planet.
In 2020, scientists on the “night” side of a flooded planet were able to see the cast iron rain.
2013 In October, astronomers were able to see the first evidence of the existence of clouds on one of the first Kepler exoplanets.
But there are as many planets that allow scientists to explore the mysteries of their atmosphere as planets whose cloud cover is so dense that it is simply impossible to study them spectroscopically. The clouds on those planets are so dense that the starlight does not exceed it. As a result, it is not possible to observe the deeper layers of the exoplanet atmosphere, which contain the knowledge that scientists are most interested in.
“We found many clouds: certain particles, not molecules, but small droplets, that are suspended in those atmospheres.” We do not know what it is made of, but they damage our observations and make it difficult for us to assess the composition and concentration of important molecules, such as water and methane, “said Gao.
Exoplanet researchers have tried for years to understand for themselves and explain to others what they see, what those drops are. They modeled various aluminas, such as corundum, which forms rubies and sapphires, molten molten salts such as potassium chloride, molded silicon oxides, or silicates such as quartz, the main component of sand. Zinc and manganese oxides, which form rocks on Earth, and organic hydrocarbons were modeled.
According to Gao, all of these exotic clouds can be in the form of liquid and solid aerosols.
The atmospheric models of exoplanets were adapted from models designed for Earth’s atmosphere, and then adapted to planets like Jupiter, whose stormy atmosphere contains huge clouds of methane and ammonia. These models were later refined to model the hot Jupiter atmosphere with temperatures up to 2500 ºC.
Their goal was to evaluate different atmospheric gases made up of different atoms or molecules to discover how they condense into droplets that grow or evaporate as they can travel through the atmosphere.
“The idea was that the formation of all kinds of clouds was determined by the same physical principles,” said Gao, who also modeled the Venus sulfuric acid cloud.
“I took that model and applied it to the rest of the galaxy, giving it the ability to model both silicate and clouds of iron and salt,” said the study leader.
But modeling in itself is not very valuable. After creating any model, it is necessary to ensure its reliability by comparing the modeling data with the observation data. The scientists have observational data for the atmospheres of about 70 exoplanets, and Gao and his colleagues compared their model’s predictions with 30 of these observational data sets.
Such a comparison has ruled out some of the more exotic types of data that some scientists have theoretically proposed in recent years because they require too much energy to condense.
But some types of clouds, like silicon, condense fairly easily. Gao and his colleagues discovered that silicon clouds dominate a relatively large temperature range, from 900 to 2,000 degrees Kelvin.
Aluminum and titanium oxides have also been found to condense into high-flying clouds on the hottest hot jupiters, while on exoplanets with a cooler atmosphere, those clouds fly lower and are hidden from observers by clouds. higher silicate.
If the planets were even colder, the same silicate clouds would fly below and visibility would not be affected in the upper atmospheric layers.
Therefore, based on the results of his simulations, P. Gao classified hot Jupiters into two temperature groups: the first has a surface temperature of 900K to 1400K, the second above 2200K.
In both groups, the upper layers of the atmosphere are transparent, allowing a detailed study of the atmosphere itself.
“The presence and thickness of various exoplanet clouds have already been identified and measured in previous studies, but only by looking collectively at a large sample of such atmospheres can we analyze the physics and chemistry of these distant worlds. The dominant type of cloud on these planets is as simple as sand, because it is basically sand, so it will be very interesting in the future to measure the spectral data of the clouds when the James Webbo Space Telescope (JWST) is raised, “he said. Hannah Wakeford, co-author of the Bristol study. universities (UK).
With the advent of JWST, astronomy, cosmology, and other space sciences should take a huge leap forward, as it will be humanity’s first tool capable of carefully analyzing the atmosphere of distant planets.
But by “learning to work,” JWST will direct its attention in the infrared spectrum to nearby planets like Jupiter. It can be expected that even on the neighboring planet, in the deepest layers of its atmosphere, we can see the clouds that the authors of the recent scientific work have described.
But there is a downside to this study, which scientists have openly pointed out. His model did not fully appreciate the differences between the day and night planets, despite the fact that most hot Jupiters are flooded with their star.
“The downside to our study is that we did not assess the three-dimensional nature of warm giants, which are likely to be flooded with their hot stars, using one-dimensional models,” the study authors wrote.
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On the other hand, it is highly likely that such deficiency will not fundamentally change job performance. Because, as the study authors added, “these effects are unlikely to significantly change our conclusions, since the observed mean temperature profile in the terminator, estimated during transmission, should be more similar to the mean global temperature profile we used in our modeling than the extreme daytime or nighttime temperature profiles. “
Going forward, Gao and colleagues intend to expand their model’s capabilities and observe more different exoplanets, as well as some stars (brown dwarfs). Basically, these stars are still gas giants, only they are so massive that they are almost stars already, even though they have an atmosphere and a cloud.
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