Exploring the Exoplanet GJ504b
Announced on June 29 at 2:00 PM, new research on the exoplanet GJ504b—first identified in 2013—has revealed salt clouds in its atmosphere. Located less than 60 light-years from Earth, this world is the coldest companion ever detected using ground-based telescopes, with temperatures around 290 degrees Celsius. Estimated to be between 2.5 and 4.5 billion years old, GJ504b offers a rare glimpse into planetary evolution.
Its orbit is more than 40 times farther from its star than Earth is from the Sun. Spectral analysis shows that GJ504b is about 10% smaller than Jupiter but nearly 25 times more massive. Researchers added salt clouds to their models to resolve a physically unlikely thermal structure. They tested three cloud types, and only the salt-based ones matched the observational data. These clouds likely consist of potassium chloride or zinc sulfide.
Atmosphere and Unique Traits of GJ504b
The atmosphere of GJ504b contains water vapor, carbon monoxide, methane, ammonia, and hydrogen sulfide. Evidence suggests it may harbor more heavy elements—such as carbon, oxygen, and sulfur—than its host star, a characteristic also seen in Jupiter.
“GJ504b is the coldest companion that has been discovered using ground-based telescopes,” noted Anish Baburaj.
“Numerous observations from Earth couldn't study it in detail due to its faint glow, making this object an ideal target for James Webb,” Baburaj added. “After obtaining the spectrum, researchers immediately realized they were dealing with an unusual object,” he emphasized. This marks the first time salt clouds have played a key role in explaining the spectrum of such an object.
An illustration of the hazy gas giant GJ504b with a pinkish hue (Credit: NASA/Goddard Space Flight Center) highlights the object's uniqueness in astronomical research.
The discovery of salt clouds on GJ504b opens new frontiers in understanding atmospheric processes on exoplanets. This study could advance the analysis of similar objects in our galaxy, particularly through next-generation telescopes like James Webb. As an example of an exoplanet with distinctive atmospheric features, GJ504b may help astronomers better comprehend how atmospheric conditions form and evolve on planets beyond our Solar System.
As researchers continue to uncover the mysteries of GJ504b, it's worth noting that the James Webb Space Telescope recently detected a significant temperature spike on another exoplanet, highlighting the advancements in our understanding of these distant worlds. Such discoveries not only deepen our knowledge of planetary atmospheres but also provide crucial insights into their evolutionary paths.