In a landmark achievement, astronomers employing the NASA/ESA/CSA’s James Webb Space Telescope have detected silicon monoxide (SIO) in the atmosphere of the exoplanet WASP-121B. This marks the first definitive identification of the molecule in a planetary atmosphere beyond our solar system.

WASP-121B, discovered in 2016 via the Wasp-South survey, is an exoplanet approximately 1.87 times the diameter of Jupiter and 1.18 times its mass. It orbits its parent star,Wasp-121,at an extremely close range,completing an orbit in just 1.3 days.

Located about 881 light-years from Earth in the constellation of Puppis, WASP-121B is classified as an “Ultrahot Jupiter” due to its extreme proximity to its star. Were it any closer, the star’s gravitational forces would likely tear the planet apart.

The temperature on the planet’s sun-facing side exceeds 3,000°C, while the night side registers a comparatively cooler 1,500°C. This drastic temperature difference makes WASP-121B an ideal subject for studying exoplanetary atmospheres.

Silicon Monoxide Discovery

“The detection of silicon monoxide in the WASP-121B atmosphere is very revolutionary,” said Dr. anjali Piette of the University of Birmingham. “This is the first convincing identification of this molecule in any planet’s atmosphere.”

“The detection of silicon monoxide in the WASP-121B atmosphere is very revolutionary.”

The presence of silicon monoxide is important because it typically exists in solid form or in extreme stellar environments.On WASP-121B, the intense heat transforms the compound into a gas, allowing the James Webb Telescope to detect it in the upper atmosphere.

Methane on the night Side

In addition to SIO, the James Webb Telescope also detected water (H2O), carbon monoxide (CO), and methane (CH4) in WASP-121B’s atmosphere. The presence of methane on the night side was notably surprising. “Considering the night side temperature is still very high, we did not expect to find methane,” said Dr. Piette.

Methane is typically unstable at such high temperatures, suggesting a process of vertical mixing, where gas moves from lower atmospheric layers to the upper atmosphere, making it visible through infrared light.

Planetary Formation

Analysis of the ratios of elements like carbon-hydrogen (C/H), oxygen-hydrogen (O/H), and silicon-hydrogen (Si/H) suggests that WASP-121B’s atmosphere likely formed through the accumulation of solid materials like rocks and dust during its formation.

“The temperature of the afternoon side is very high so that the heat -resistant material that is usually in the form of solid can be in the form of gas in the atmosphere of this planet,” explained Dr.Thomas Evans-Soma from the University of Newcastle.

Scientists used phase curve observations to monitor the planet’s light as it orbited its star, allowing them to study both the day and night sides.

These observations have provided an unprecedentedly detailed picture of the chemical composition of WASP-121B’s atmosphere on both sides of the planet.

“The success of James Webb in detecting and mapping the chemical elements of the WASP-121B atmosphere shows how extraordinary the ability of this telescope is,” said Dr. Piette.”This is the initial milestone for the study of exoplanet atmosphere in the future.”

The findings, published in Nature Astronomy, highlight WASP-121B as a fascinating exoplanet and mark a new era in the study of planetary atmospheres and the potential discovery of rare molecules in extreme environments beyond our solar system.