Brown dwarfs, often referred to as “failed stars,” are a fascinating type of celestial object. They are too large to be considered planets, yet too small to undergo the fusion process necessary to become fully-fledged stars.
One such brown dwarf, named WISEP J193518.59–154620.3 (or W1935 for short), is believed to be observable from Earth, especially towards the north and south poles. Astronomers suspect that it may exhibit an aurora similar to the mesmerizing aurora borealis, but on a much brighter scale.
Research featured in the journal Nature utilized NASA’s James Webb Space Telescope (JWST) to study W1935. This brown dwarf is relatively close to us in the galaxy, approximately 47 light-years away from Earth.
Upon pointing a space telescope the size of a tennis court towards the brown dwarf, researchers noticed a peculiar glow emanating from it.
“We were expecting to detect methane as it’s abundant in these brown dwarfs. However, instead of absorbing light, we found methane emitting light,” stated Dr. Jackie Faherty, the lead author of the study. “My initial reaction was, ‘What’s going on? Why is this object emitting methane?'”
Co-author Dr. Ben Burningham mentioned to BBC Science Focus that in the search for alien auroras in objects like W1935, astronomers traditionally focused on emissions from other gases found higher up in the object’s atmosphere.
“Methane emissions were not anticipated to be significant, but now it appears to be a significant factor,” he added.
Computer modeling of W1935 to elucidate the unusual methane emissions revealed a surprising temperature inversion, where the atmosphere gets warmer with increasing altitude. This phenomenon is common for planets orbiting stars but unexpected for an isolated object like W1935 without an apparent external heat source.
Further investigation led researchers to compare W1935 with Jupiter and Saturn from our solar system, which also exhibit methane emissions and temperature inversions.
The observed features in the solar system giants are attributed to auroras, luminous phenomena generated when energetic particles interact with the planet’s magnetic field and atmosphere.
Auroras are known to heat the upper atmosphere of planets, aligning with the researchers’ findings regarding W1935.
However, a missing element in the puzzle was the source of particles causing high-energy auroras in our solar system, which stem from the sun and travel as solar wind. Since W1935 is a rogue star without a host star, solar wind was ruled out as a possible explanation.
Scientists hypothesize that an undiscovered active satellite could be generating the alien aurora observed in W1935, akin to moons around Jupiter and Saturn that expel material into space enhancing the gas giants’ auroras.
“W1935 presents an intriguing expansion of solar system phenomena without any stellar illumination to clarify it,” Faherty remarked. “With Webb, we can delve into the chemistry and unravel the similarities or differences in auroral processes beyond our solar system.”
About our experts
Jackie Faherty is a senior scientist and education manager at the American Museum of Natural History, focusing on detecting and characterizing brown dwarfs and exoplanets. She advocates for increasing diversity in STEM fields through her unique outreach efforts.
Ben Burningham is an Associate Professor and Head of Outreach at the University of Hertfordshire, specializing in brown dwarfs, substellar objects, and superplanets. Burningham has contributed to research published in the Astrophysical Journal, Nature, and Astronomical Journal.
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Source: www.sciencefocus.com
