Summary
By the end of this article, you will understand how astronomers use light to read the chemical fingerprints of giant planets, and what those chemicals reveal about how planets are born.
Quick Facts
Surprise: The planet YSES 1 b is 14 to 22 times more massive than Jupiter!
Surprise: Astronomers detected a rare type of heavy carbon (Carbon-13) floating in the planet's atmosphere.
Salient Idea: The inner planet spins twice as slow as the outer planet, possibly slowed down by a magnetic field.
Surprise: These huge planets orbit their star at 160 and 320 times the distance Earth is from the Sun.
The Discovery: Reading Planetary Barcodes
In 2024, scientists used the powerful VLT telescope in Chile to look at a star system called YSES 1. This system has two massive planets, called super-Jupiters, orbiting incredibly far from their star. But scientists did not just take a picture—they used an upgraded instrument called CRIRES+ to break the planets’ light down into a spectrum, like a rainbow. They found a Surprise: by reading the missing colors in the light, they detected the exact chemical fingerprints of water, carbon monoxide, and a heavy isotope of carbon (Carbon-13). It is the first time water and carbon monoxide have been detected on the smaller, outer planet, YSES 1 c. This discovery proves we can read the weather of alien worlds with incredible precision.
High-resolution spectroscopic characterization of young super-Jovian planets enables precise constraints on elemental and isotopic abundances of their atmospheres.
— Yapeng Zhang et al.
The Science Explained Simply
This is NOT a story about planets forming like Earth, slowly gathering rocks over billions of years. Super-Jupiters pose a major problem for astronomers: they are too huge and too far from their star to form the ‘normal’ way. The Salient Idea here is using chemistry as a time machine. By measuring the ratio of carbon to oxygen (C/O) in the planets’ atmospheres, scientists can figure out where they were born. The inner planet has a C/O ratio matching its host star, suggesting it formed very quickly when a massive cloud of gas collapsed under its own gravity. It is a top-down formation, completely different from how rocky, terrestrial planets are made.
Comparing chemical abundances in the atmospheres of both companions and the system’s dynamical properties provides unprecedented details for tracing its formation history.
— The Research Team
The Aurora Connection
What determines how fast a planet spins? The inner planet, YSES 1 b, spins much slower than the outer planet. Why? The secret might be magnetic fields. When a giant planet forms, it is surrounded by a spinning disk of gas and dust. If the planet has a strong magnetic field—much like the one that causes the auroras on Earth—that field interacts with the disk. Over millions of years, this magnetic connection acts like a giant, invisible brake, slowing the planet’s rotation. Our own magnetic field protects our atmosphere from the solar wind and creates the Northern Lights, but on young super-Jupiters, magnetic fields literally shape the physical spin of the world.
Massive companions can effectively ionize the CPDs [circumplanetary disks] and spin down through interactions between magnetic fields.
— Astrophysics Theory
A Peek Inside the Research
How do you see a dim planet next to a blindingly bright star? It requires intense data processing. The team had to physically block the star’s light, but some still leaked into their instruments. To fix this, they used advanced math—specifically, polynomial equations—to model the exact brightness of the leaking starlight and subtract it from the data pixel by pixel. Only then could they extract the faint, pure light of the super-Jupiters. This Story of problem-solving shows that modern astronomy is just as much about writing brilliant software as it is about building giant telescopes.
To remove the stellar contamination, we carried out additional corrections on the 2D data before spectrum extraction.
— Yapeng Zhang
Key Takeaways
High-resolution spectroscopy allows scientists to find specific molecules like water and carbon monoxide light-years away.
A planet's ratio of carbon to oxygen acts as a chemical fingerprint to tell us exactly where and how it formed.
Comparing multiple giant planets in the exact same system helps astronomers test and rule out different formation theories.
Magnetic braking from a planetary disk can drastically slow down a gas giant's rotation speed.
Sources & Further Reading
Frequently Asked Questions
Q: What exactly is a super-Jupiter?
A: A super-Jupiter is a gas giant planet that is significantly more massive than our own Jupiter. The planets in this study, YSES 1 b and YSES 1 c, are estimated to be roughly 14 and 6 times heavier than Jupiter, respectively.
Q: How do astronomers know what chemicals are in an exoplanet’s atmosphere?
A: They use a technique called spectroscopy. Different chemicals absorb specific colors of light. By looking at a planet’s light, scientists see dark ‘lines’ where colors are missing, which act like a chemical barcode.
