An exoplanet located 154 light-years away maintains a radius of approximately 1.6 times that of Earth while carrying five times Earth’s mass. Designated HD 3167 b, this rocky super-Earth orbits its host star in less than a single terrestrial day, completing one full circuit in roughly 0.959 days, little less than 23 hours. Identified by analyzing data from the James Webb Space Telescope of NASA, the European Space Agency, and the Canadian Space Agency, it stands as a rocky planet covered in lava while simultaneously being the coldest of this type ever observed.
James Webb Space Telescope Captures Thermal Anomalies
Observations from the James Webb Space Telescope revealed that the planet exhibits a thermal emission lower than expected for a bare rock. This unexpected result on the illuminated hemisphere points toward a functioning atmosphere capable of redistributing heat to the dark side. Additional components capable of reflecting part of the stellar radiation could also contribute to the phenomenon.
Researchers used the secondary eclipse method to measure the thermal radiation emitted by HD 3167 b as it passed behind its star. Because the planet is in synchronous rotation, its permanent dayside faces intense stellar radiation that melts surface silicates.
University of Chicago Team Publishes Findings
Scientists at the University of Chicago, led by Brandon Park Coy, published these findings in The Astrophysical Journal Letters. The measured dayside temperature came in colder than expected for a rocky body without an atmosphere, prompting the team to evaluate atmospheric heat transport mechanisms.
A Natural Laboratory for Early Earth Evolution
Studying HD 3167 b offers planetary scientists a benchmark for understanding extreme celestial conditions and early planetary evolution. The planet serves as a natural laboratory for examining how rocky bodies behave when subjected to intense stellar heat.
The presence of an envelope around such a close-in world challenges assumptions about how easily stellar winds strip gases from roasted exoplanets. The surprising thing is that the closer a rocky planet orbits to its star, the harder it should be for it to have an atmosphere, because it is bombarded by stellar wind,
Kite stated, But it seems that many of these lava worlds have one.
Unresolved Questions Over Gas Composition
Investigators have not yet confirmed the precise chemical makeup of the gas envelope surrounding HD 3167 b.
Future observation cycles using the James Webb Space Telescope will aim to isolate specific spectral lines to determine the exact gas components. These upcoming measurements remain crucial for confirming how an ultrashort-period world retains its gaseous envelope despite heavy stellar bombardment, offering the first fundamental step to unveil the secrets of the birth of our ecosystem orbiting the Sun.
