Astronomers utilizing the James Webb Space Telescope (JWST) have identified an unusual atmospheric feature on GJ504b, a celestial object often referred to as the “Pink Planet”: clouds made of salt. This discovery marks the first observation of such a phenomenon in this temperature range.
An Unexpected Atmospheric Composition
The findings, published in The Astronomical Journal, were made by a research team led by Northwestern University. GJ504b, formally known as a planetary-mass companion, was discovered in 2013. It orbits a star similar to our sun, located 57 light-years away. The object has a temperature of 550 degrees Fahrenheit, which is considered unusually cold for a giant planet, as most exoplanets typically range from 1,000 to 2,000 degrees Fahrenheit.
Aneesh Baburaj, the study’s leader and a postdoctoral associate at Northwestern’s Center for Interdisciplinary Exploration and Research in Astrophysics, expressed surprise at the discovery. “People have theorized that salt clouds might exist in the atmospheres of companions at these temperatures… but people in general just don’t observe any kind of signatures of clouds in such temperatures,” Baburaj stated in an interview.
The planetary-mass companion is estimated to be 25 times the mass of Jupiter and is between 2.5 billion and 4 billion years old. According to Baburaj, its advanced age contributes to its lower temperature, as giant planets cool over time.
Webb Telescope’s Capabilities
Studying GJ504b from Earth has been challenging due to its low temperature, which has made its faint light difficult for traditional telescopes to observe. However, the JWST, with its ability to capture infrared images, successfully observed the object in just two hours. The telescope spreads light into spectra, revealing chemical fingerprints within an atmosphere.
By analyzing the faint light captured by the JWST, researchers created a “fingerprint” that indicated the presence of water vapor, methane, carbon dioxide, ammonia, and other molecules. The data only aligned with existing models when salt clouds were included, suggesting they were influencing the detected light.
“We were really, really amazed by how easy it was to detect with James Webb, as opposed to like it had been close to impossible from the ground,” Baburaj commented.
Understanding Planetary Atmospheres
Salt clouds represent a unique atmospheric condition, existing in a temperature range between those suitable for water clouds on Earth and ammonia clouds on Jupiter, and cooler environments where silicate clouds might form on hotter worlds. The JWST’s power to detect colder atmospheric conditions opens avenues for further research into similar celestial objects.
Baburaj noted that the telescope’s capabilities will allow scientists to detect colder objects, many of which may exhibit higher metal-to-hydrogen ratios compared to our sun.
Helene Elliott is the senior reporter for News Raise. She covers Science news. She also has a keen interest in photojournalism. Helene holds a nomination for the prestigious Red Smith Award. She is married to author Dennis D’Agostino, a former publicist with the New York Mets.
