The James Webb space telescope has identified robust evidence of a dense atmosphere on the rocky exoplanet TOI-561 b, a super-Terra located about 280 light-years from Terra. Esse extreme world, with a radius approximately 1.4 times that of Earth, orbits its star in less than 11 hours and features a daytime hemisphere with temperatures high enough to form a global magma ocean.
Observations indicate that the illuminated side of the planet registers around 1,800°C, a value lower than the 2,700°C predicted for a bare rocky surface without gases. Essa difference suggests the presence of a substantial atmospheric layer that redistributes heat through winds and absorbs some stellar radiation.
- The planet belongs to a rare class of ultrashort-period exoplanets.
- Its low density already intrigued scientists before the new measurements.
- The host star is about 10 billion years old, twice the age of Sol.
Characteristics of the exoplanet TOI-561 b
TOI-561 b stands out for its extreme proximity to the star, which places it in tidal locking, with one side permanently facing the source of light and heat. Essa configuration results in surface conditions that melt rocks, creating vast expanses of molten lava.
Data collected by James Webb’s NIRSpec instrument, during more than 37 hours of continuous observation, captured nearly four complete orbits of the planet. Essas measurements made it possible to map variations in infrared brightness and confirm that the observed temperature cannot be explained solely by an exposed rock.
The composition of the star, poor in heavy metals and located in the thick disk of Via Láctea, influences the formation of the planet. Pesquisadores consider that TOI-561 b may have a smaller iron core and a mantle with less compact minerals, contributing to its reduced density.
Observation method and data analysis
The technique used involves measuring infrared emission during secondary eclipses, when the planet passes behind the star. Sem atmosphere, the expected brightness would be greater due to the high direct surface temperature.
The observations revealed an emission spectrum that points to volatile gases, possibly including water vapor, carbon dioxide and silicates. Esses components form clouds that reflect some of the starlight, helping to moderate warming in the upper layers.
The team analyzed theoretical models to compare with real data. Apenas thick atmosphere scenarios reproduced the measured temperatures, ruling out alternative explanations such as variations in isolated rock composition.
The observation program General Observers 3860 provided a detailed data set. Futuras analyzes should refine thermal mapping around the planet and identify specific compounds in the atmosphere.
Atmospheric retention mechanisms
On planets so close to their stars, intense radiation often removes gases over billions of years. In the case of TOI-561 b, a dynamic balance between the magma ocean and the atmosphere appears to keep the volatiles in place.
Gases released from the molten interior feed the atmospheric layer. Parte of these compounds is reabsorbed by magma, limiting loss to space.
This continuous interaction requires a planet rich in volatile substances since its initial formation. The description of a “wet lava ball” illustrates this cyclic process of exchange between surface and gases.
Low density and internal composition
The density of TOI-561 b is lower than expected for a rocky world with terrestrial composition. Essa characteristic led to the initial hypothesis of a small core and expanded mantle.
The presence of atmosphere contributes to the greater apparent volume, reducing the calculated density. The old, iron-poor star suggests formation in a primordial environment other than Sistema Solar.
Less dense minerals in the mantle align with observed stellar chemistry. Essa combination explains why the planet doesn’t fit into standard models of super-Earths.
Observations made by James Webb
The telescope monitored the system continuously, recording variations in brightness during multiple orbits. Essa approach captured fine details about heat distribution.
NIRSpec provided near-infrared spectra, essential for estimating temperatures and detecting atmospheric signatures. Initial results already indicate greater complexity than expected.
The team continues to process the full data set. Novas information about thermal variations around the planet should emerge in subsequent analyses.
Implications for exoplanet studies
This discovery reinforces that extreme rocky worlds can sustain long-lasting atmospheres. Ela expands the understanding of gas retention in hostile environments.
Ultrashort-period planets gain renewed attention as targets for atmospheric characterization. Similar Observações in other systems help refine models of planetary evolution.
The strongest evidence yet for an atmosphere on a rocky exoplanet opens avenues for future investigations. Técnicas of James Webb applied to similar targets promise more revelations about planetary diversity.
