James Webb Space Telescope unveils secrets of a nearby cold brown dwarf

Credit: NASA

The James Webb Space Telescope (JWST), the most powerful space telescope ever built, has recently provided astronomers with a closer look at a fascinating cosmic neighbor, WISEPA J182831.08+265037.8, also known as WISE 1828.

Situated just over 32 light years from Earth, this object is an exemplary specimen of the coldest and dimmest objects in our cosmic vicinity known as Y dwarfs.

These are brown dwarfs, celestial bodies that lie in the mysterious realm between planets and stars, lacking the mass to ignite hydrogen fusion like stars do. WISE 1828, with its mass roughly equivalent to 10 Jupiters, falls well below the threshold for starhood.

This recent study, spearheaded by Ben Wei Peng Lew and his team at the Bay Area Environmental Research Institute, focused on dissecting the atmosphere of this intriguing brown dwarf using JWST’s Near-Infrared Spectrograph (NIRSpec).

By employing high-resolution observations, the team embarked on a detailed atmospheric investigation, marking a significant leap in our understanding of such distant worlds.

The JWST’s observations have revealed a rich cocktail of chemicals within WISE 1828’s atmosphere, including water, carbon monoxide, carbon dioxide, methane, ammonia, and, notably, hydrogen sulfide.

This marks the first instance of hydrogen sulfide being detected in the atmosphere of a Y dwarf, highlighting the telescope’s unprecedented capabilities in probing the compositions of distant astronomical objects.

The study further delves into the chemical makeup of WISE 1828, indicating an abundance of oxygen and sulfur relative to hydrogen that surpasses solar levels, while the nitrogen to hydrogen ratio appears to align closely with solar abundance. Interestingly, the methane levels were found to be lower than expected.

Through sophisticated atmospheric modeling, the researchers were able to estimate the brown dwarf’s metallicity—a measure of the abundance of elements heavier than hydrogen and helium.

The findings suggest a metallicity that varies across different models, pointing to the complexity of accurately determining such characteristics for distant objects. Additionally, the carbon to oxygen ratio was calculated, providing insights into the dwarf’s atmospheric composition.

The models also offered estimates for WISE 1828’s physical dimensions and temperature, which appear to vary depending on the modeling approach used.

According to one model, the brown dwarf measures about 1.23 times the radius of Jupiter and boasts a temperature of 534 K, while another model proposes a slightly smaller and cooler profile.

This groundbreaking research, shared on the preprint server arXiv, underscores the JWST’s role in pushing the boundaries of our knowledge about the universe.

By shedding light on the atmospheric conditions of a Y dwarf like WISE 1828, astronomers are gaining invaluable insights into the processes and compositions that define these celestial bodies.

As we continue to explore the cosmos, discoveries like these are vital in piecing together the vast, intricate puzzle of our universe.

The research findings can be found in arXiv.

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