Have you ever wondered if there are other Earths out there? Well, recent discoveries using NASA’s James Webb Space Telescope (JWST) might bring us closer to that answer. Researchers believe they have found evidence of a possible atmosphere surrounding the rocky exoplanet 55 Cancri e, located a mere 41 light-years from Earth! This finding, published in the journal Nature, marks a significant step forward in our quest to understand exoplanets and their potential for harboring life.
What is 55 Cancri e?
55 Cancri e is a super-Earth, meaning it’s a rocky planet significantly larger than Earth but smaller than gas giants like Jupiter. It orbits a Sun-like star called 55 Cancri A, which is slightly older and slightly cooler than our Sun. Unlike Earth, 55 Cancri e is tidally locked, meaning the same side of the planet always faces its star. This results in scorching temperatures on the dayside, estimated to be around 4,000 degrees Fahrenheit (2,200 degrees Celsius).
How Did We Find the Atmosphere?
Traditionally, astronomers have focused on detecting atmospheres around gas giant exoplanets. These atmospheres are thicker and easier to spot using transit spectroscopy, a technique that analyzes the light filtering through a planet’s atmosphere during a transit event (when the planet passes in front of its star). However, rocky planets like 55 Cancri e present a bigger challenge due to their thinner atmospheres.
The JWST, with its advanced infrared capabilities, is revolutionizing exoplanet characterization. Researchers used the telescope’s Mid-Infrared Instrument (MIRI) to study the thermal emission (heat radiating) from 55 Cancri e. If the planet had no atmosphere or a very thin one, the dayside would be expected to release this heat readily, resulting in a much higher measured temperature.
However, the MIRI data revealed a surprising twist. The dayside of 55 Cancri e displayed a cooler temperature than anticipated, around 2,800 degrees Fahrenheit (1,540 degrees Celsius). This suggests the presence of an atmosphere that could be trapping some of the heat.
What Kind of Atmosphere Does it Have?
The specific composition of the atmosphere on 55 Cancri e remains a mystery. However, the cooler temperature hints at the presence of a substantial atmosphere, possibly dominated by gases like carbon dioxide (CO2) or carbon monoxide (CO). Future observations with the JWST and other telescopes may help us identify the specific molecules present and constrain the atmospheric pressure.
Is 55 Cancri e Habitable?
While the discovery of a possible atmosphere is exciting, it’s important to manage expectations. Due to its extreme proximity to its star and the likely presence of a scorching dayside, 55 Cancri e is not considered a viable candidate for life as we know it. However, this finding opens doors for further exploration of rocky exoplanets and the potential for atmospheric diversity.
The Future of Exoplanet Atmospheres
The JWST’s groundbreaking observations pave the way for a new era of exoplanet research. As we gather more data on 55 Cancri e and other rocky exoplanets, we can refine our understanding of atmospheric formation and evolution. This knowledge will be crucial in the ongoing search for habitable worlds beyond our solar system.
Source: [1] Renyu Hu et al., “Signs of a Substantial Atmosphere on the Exoplanet 55 Cancri e,” Nature (2024), https://astrobiology.arizona.edu/news/nasas-webb-hints-possible-atmosphere-surrounding-rocky-exoplanet