Since the Kepler missions in 2009, NASA has discovered proof of exoplanets or planets outside of our solar system. A further expedition led to the discovery of specific exoplanets called 'Hot Jupiters,' gigantic gas planets that are so close to their stars, reaching extremely high temperatures.
A recent study revealed that Hot Jupiters have exotic atmospheres with clouds made of aluminum oxide and produces titanium rain, and can reach temperatures up to 4,600 F. Since Hot Jupiters are so easily found and are excellent candidates for atmospheric observation with future telescopes, the astronomers have created a cloud atlas for these exoplanets revealing a variety of cloud and planet types.
The ceiling mass limit for a Hot Jupiter measure to the equivalent of 13.6 Jupiters. Bigger than that, it would fuse deuterium (heavy hydrogen) and would be a brown dwarf, an object too large to be a planet yet too small to be a star.
With Peter Gao leading the scientists from the UK, USA, and Canada, their study was meant to catalog the type of atmospheres different Hot Jupiters contain. The study explains, 'Aerosols are common in the atmospheres of exoplanets across a wide swath of temperatures, masses, and ages.
These aerosols strongly impact observations of transmitted, reflected, and emitted light from exoplanets, obfuscating our understanding of exoplanet thermal structure and composition. More knowledge on 'dominant aerosol composition would facilitate interpretations of exoplanet observations and theoretical understanding of their atmospheres,' they wrote.
Our gas giants, Jupiter, Saturn, Uranus, and Neptune which have thick, hazy atmospheres, have a similar atmosphere as Hot Jupiters which contain 'liquid or solid droplets of silicon and oxygen, like melted quartz or molten sand.' Understanding the exoplanet atmospheres are helping the astronomers understand our own solar system.
The hottest of hot Jupiters are the strangest of faraway exoplanets, according to new findings from our @NASASpitzer telescope. The heat on this kind of planet is so extreme, planetwide meltdowns tear apart the molecules that make up the atmosphere: https://t.co/40fJN4PuN2 pic.twitter.com/0O1Nbx8C3N — NASA (@NASA) January 24, 2020
Kepler Missions
'There have been models that predict various compositions, but the point of this study was to assess which of these compositions actually matter and compare the model to the available data that we have.' In 2019, scientists found water vapor, possibly even rain, in one exoplanet's atmosphere.
In October 2013, researchers found evidence of cloud cover on one of the first exoplanets discovered by Kepler 7b. This year, astronomers discovered evidence of molten iron rain in the atmosphere of another exoplanet's tidally-locked nightside.
However, the clouds are so thick that beyond the outer atmosphere of exoplanets, there are no other data regarding the rest of the planet. Gao said, 'We have found a lot of clouds: some kinds of particles - not molecules, but small droplets - that are hanging out in these atmospheres.' Astronomers don't know what the droplets are made of, but they are contaminating observations that hinder the team from assessing the composition and presence of important molecules like methane and water.
'What I have done is to take this model and bring it out to the rest of the galaxy, making it able to simulate silicate clouds and iron clouds and salt clouds," said Gao. His team then discovered that silica clouds temperatures range between 1100 F to 3200 F.
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Understanding Our Jupiter
Hannah Wakeford, an astrophysicist at the University of Bristol said that the bigger picture of analyzing the clouds is to 'pick apart the physics and chemistry in the atmospheres of these worlds.' One dominating cloud species seems to be common as sand, which they will be able to measure using the upcoming James Webb Space Telescope (JWST).
The JWST launch will enable closer examination in all areas of space science and have a closer look at exoplanet atmospheres, as well as our own planets like Jupiter. Since there are thousands of exoplanets while there is only one Jupiter, studying many Hot Jupiters and determining the average can be compared to our singular one.
Jonathan Fortne from UC Santa Cruz shared that studying planetary atmospheres in the solar system contain clear images. With exoplanets, there is no context, only dots, and shadows. Even with those limitations, he continues, 'what we do have to make up for that is a much larger sample size. Trends, such as cloudiness can be discovered, as well as 'planetary temperature, something that we just don't have the luxury of in our solar system.'
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