The search for planets outside our solar system has revolutionized astronomy. Among the most intriguing systems, we have discovered the so-called WASP exoplanets, a family of worlds that continue to amaze the scientific community. Their study is changing our understanding of planetary formation, atmospheric chemistry, and the extreme conditions that can exist elsewhere in the universe.
In this article, we'll take you on an in-depth exploration of WASP exoplanets, which have been at the center of some of the most amazing discoveries of recent years. You'll see how these gas giants, teeming with unusual phenomena, have forced us to rethink existing theories and have opened up new questions about the diversity and evolution of planets in the galaxy.
What are WASP exoplanets and how were they detected?
WASP exoplanets take their name from the international Wide Angle Search for Planets project , a collaboration that uses automated observatories in both hemispheres to monitor millions of stars. These observatories detect periodic dips in star brightness, which typically indicate a planet passing in front of its star.
Since its inception, the WASP project has detected thousands of exoplanet candidates and confirmed a large number of them, some of which stand out for having radically different properties from the planets in our solar system. These discoveries have been made possible by techniques such as transit photometry and measuring the radial velocity of the host stars.
WASP-193b: The planet lighter than cotton candy
One of the biggest recent stirs has been the discovery of WASP-193b . Imagine a planet of colossal size, 50% larger than Jupiter, but with a much smaller mass: only one-tenth that of the giant of our solar system.
The result? An absurdly low density by planetary standards: a mere 0,059 grams per cubic centimeter. To give you an idea, it's practically like cotton candy floating in space! In fact, only Kepler-51d surpasses WASP-193b in low density, although it is much smaller.
Discovering such an oddity led scientists to doubt their own measurements. Was it a mistake, an instrumental error, or were they truly looking at such a porous planet? After repeating the processes and validating the data with different methods and observatories, the team confirmed that the measurements were real.
Why is WASP-193b so strange? Standard planetary physics cannot explain how a planet can inflate to that extent without becoming unstable or dispersing. It is suspected to have a massive atmosphere composed primarily of hydrogen and helium, extending far beyond that of any known gas giant.
This discovery calls for more detailed observations with instruments like the James Webb Telescope, as studying its atmosphere can shed light on phenomena of planetary evolution that we do not yet understand.
How to confirm such an unusual exoplanet
Confirming the existence and characteristics of such an unusual planet required combining observations from multiple telescopes and spectrographs. The process began with the detection of periodic transits by WASP-South. The planet's size was verified by analyzing how much the light from the host star dimmed during each transit, and its mass was subsequently calculated using radial velocity spectroscopy.
This rigorous methodology ruled out alternative explanations and confirmed that the dips in brightness were caused by a real planet and not by other stellar phenomena.
In addition, the collaboration benefited from Chilean observatories such as TRAPPIST-South and SPECULOOS-South to maintain detailed monitoring, which is essential for validating such extreme exoplanets.
The atmosphere and composition of WASP-193b
The mystery of WASP-193b goes even further than its density. The extended atmosphere, composed primarily of hydrogen and helium, raises enormous questions about how it can remain stable and what mechanism inflated it so much.
Current models of planetary formation fail to describe such an object. Even assuming the absence of a planetary core, the resulting density would still be inexplicably low. For now, scientists indicate that much more detail about its atmosphere will be needed to unravel its history and evolution.
Furthermore, the researchers emphasize that the existence of WASP-193b challenges the limits of what we understand as giant planets, and opens the door to the possibility that there are many more such strange worlds yet to be discovered in our galaxy.
WASP-127b: unprecedented supersonic winds and atmospheric dynamics
Turning to another of the WASP system's key players, we find WASP-127b . This is a so-called "hot Jupiter," meaning a giant gas planet with a size comparable to Jupiter, but less massive and with an orbit much closer to its star, which drives temperatures to over 1.000ÂşC.
This exoplanet has astounded astronomers thanks to its unprecedented atmospheric conditions. While one part of its atmosphere is approaching Earth, the other is moving away at incredible speeds, creating a supersonic equatorial jet stream that spins at about 33.000 kilometers per hour.
To give you an idea of ​​the magnitude, the fastest winds on Saturn barely reach 1.800 km/h, and on Earth, Cyclone Olivia in 1996 holds the record at 408 km/h.
Spectroscopic analysis confirmed the presence of water vapor and carbon monoxide in the atmosphere, crucial for deciphering the chemistry and origin of this planet. The discovery was made possible by instruments such as CRIRES+ on the VLT, allowing these phenomena to be observed despite the bright glare of the host star.
A unique opportunity to study the dynamics of exoplanets
WASP-127b represents a natural laboratory for investigating the most extreme aspects of planetary atmospheres. Mapping supersonic winds and variations in temperature and composition at different latitudes and atmospheric depths has opened new avenues of research.
Even the most subtle details, such as weaker signals from the poles—indicating colder regions compared to the equator—have been identified, something that until very recently was unthinkable on planets located more than 500 light-years from Earth.
This advance in precision helps us better understand how heat, elements, and chemical compounds circulate on gas giant planets, testing our models and enriching our understanding of our own solar system.
WASP-121b: Climatology Beyond Science Fiction
Technological advances, such as ESO's Very Large Telescope (VLT), have made it possible to analyze the atmosphere of WASP-121b in three dimensions, revealing weather patterns that seem straight out of a science fiction novel.
This planet, also known as Tylos, orbits at a distance of just 900 light-years and is considered an "ultra-hot Jupiter" due to its proximity to the star. A year on WASP-121b lasts only 30 Earth hours and exhibits a huge temperature difference between its daytime hemisphere and its nighttime hemisphere.
Atmospheric mapping has revealed complex jet streams and flows separated into various layers, transporting material from the warm side to the cold side. Elements such as iron, titanium, sodium, and hydrogen reveal the intricate structure and dynamics of the atmosphere.
What's surprising is that some elements, such as titanium, have only been detected in deep layers beneath the jet stream, hinting at an even richer atmospheric chemistry than anticipated. This underscores the potential for future investigations with even more powerful telescopes like the Extremely Large Telescope (ELT), currently under construction.
WASP-39b: The James Webb Telescope's Molecular and Chemical Catalog
The James Webb Space Telescope (JWST) has opened a new frontier in the study of exoplanets, and WASP-39b has been one of the first to benefit. This planet, about the size of Saturn but with an orbit much closer to its star, has been photographed in unprecedented detail.
The JWST has identified a multitude of molecules and elements in its atmosphere, including water, sulfur dioxide, carbon monoxide, sodium, potassium, and fragmented clouds . For the first time, sulfur dioxide has been detected as a result of chemical reactions triggered by starlight, a direct sign of photochemistry in action, something that on Earth is associated with ozone formation.
The comprehensive list of chemical ingredients allows scientists to deduce details about WASP-39b's formation and evolutionary history. Precise analysis of the abundances of different elements supports the hypothesis that the planet formed far from its star, capturing oxygen-rich materials in its youth.
These findings demonstrate the power of JWST to explore the atmospheric diversity of exoplanets, and mark the beginning of a new era in the exploration of smaller, rocky worlds in the near future.
Other fascinating cases: exoplanets with tails and escaping atmospheres
As if that weren't enough, the WASP family includes even more bizarre phenomena, such as WASP-69b . This planet is not only a gas giant similar to Jupiter, but it also loses its atmosphere in the form of a hydrogen and helium tail up to 563.000 km long, propelled by extreme stellar winds and the intense radiation from its star.
WASP-69b is one of the clearest examples of how stellar environments affect planets, giving rise to phenomena such as photoevaporation and mass loss at a rate of hundreds of thousands of tons per second.
Detailed studies of their tails are also allowing these exoplanets to be used as indicators of the activity and stellar winds of their host stars, valuable tools for understanding both the planets and the stars themselves.
