“My first thought was, what the heck?”

Graphic titled “Webb Finds Signs of Possible Aurorae on ‘Failed Star.’” The background artist concept portrays a dark blue, striped object representing a brown dwarf. It is tilted to the right. One pole is completely visible and is circled by a curtain of red representing an aurora.

W1935 is a cold, isolated brown dwarf: an object larger than Jupiter but smaller than a star. Scientists using Webb found that methane in this object’s atmosphere was emitting infrared light, instead of absorbing it as expected. Without a host star, it's unclear how W1935 generates the energy it would need for methane emission. Even more puzzling, its atmosphere seems to warm as altitude increases.The team looked to the gas giants in our solar system for a comparison. Leading theories credit aurorae (in part) for W1935’s unusual temperature inversion, which we see in Jupiter and Saturn. Could this brown dwarf also have aurorae?

This isn’t the first time aurorae have been speculated to exist on brown dwarfs. But this is the first candidate brown dwarf with the signature of methane emission, and is also the coldest auroral candidate outside our solar system. 

Graphic titled “Brown Dwarf W1935: Atmospheric Methane. Data from Webb’s NIRSpec Instrument.” Text reads: “A brown dwarf starts out like a star, yet ‘fails’ to ever have the mass for its core to burn nuclear fuel and radiate starlight. Webb found that methane in brown dwarf W1935's atmosphere was emitting infrared light, even though there was no obvious energy source. Based on parallels from our solar system, aurorae could be responsible.” Underneath is a graph showing a blue line, labeled “W1935,” with a noticeable bump near the middle. The bump is highlighted with a vertical red band labeled "methane emission C H 4". The y-axis is labeled “Brightness of Light” and the x-axis is labeled “Wavelength of Light, microns.”

Credit: NASA, ESA, CSA, Leah Hustak (STScI)

#JWST #BrownDwarf #Methane #Aurora #AAS243 #NASA #Jupiter #Saturn