Puzzling Brown Dwarf Aurora
Andy Lloyd
Puzzling Brown Dwarf Aurora
Image Credit: NASA, ESA, CSA, and L. Hustak (STScI)
The study of brown dwarfs has been enhanced by the James Webb telescope, which can peruse the spectra of light from these objects in ever finer detail. It is also managing to study brown dwarfs in parts of the electromagnetic spectrum previously untouched by other telescopes (1). This new capability has flung up a very unexpected finding about a 'cold', isolated brown dwarf, W1935, that has no host star (2). The methane in its upper atmosphere is actually emitting light, rather than just absorbing it. Such a condition implies an active aurora display. However, there is no host star present to provide the solar wind which would normally drive such a light display. The implication is that the upper atmosphere of W1935 has far more energy packed into it than its low temperature (around 200C) would allow.
Scientists suggest that a nearby active moon may be driving some of this activity, presumably through strong volcanic activity (rather like Io in orbit around Jupiter). Or instead the activity may be driven by internal atmospheric mechanisms transferring energy to the brown dwarf's upper atmosphere (a phenomenon observed on Saturn and Jupiter) or "external interactions with either interstellar plasma" (2).
So, here we have an isolated, cold 'Dark Star' which is independently emitting auroral light. This is a prediction I made many, many years ago in my book 'Dark Star' (3). At the time, I argued that these cold, failed star objects would be capable of giving out dim levels of light despite essentially appearing to be 'dead'. When discussing this, I often used to make an analogy with the glowing embers of a fire which has gone out. It's interesting to speculate that any moons orbiting a Dark Star such as W1935 would enjoy being bathed in the light from this auroral display. Indeed, the presence of such a moon might be helping to generate the effect itself!
Written by Andy Lloyd, 10th December 2024
1) Dr Sarah Casewell, interviewed on BBC Today programme 10/1/24
2) NASA Webb Telescope Team "NASA’s Webb Finds Signs of Possible Aurorae on Isolated Brown Dwarf" 9 January 2024
3) Andy Lloyd 'Dark Star: The Planet X Evidence" Timeless Voyager Press 2005