New Analysis Casts Doubt On 'Biosignatures' Found On Planet K2-18b

Initial claims that life-associated gases were detected on exoplanet K2-18b are being challenged, with independent reanalysis by Jake Taylor suggesting the data is too noisy to support such conclusions and that stronger, model-independent evidence is needed. NPR reports: Rather than seeing a bump or a wiggle that indicated a signal, 'the data is consistent with a flat line,' says Taylor, adding that more observations from the telescope are needed to know what can be reliably said about this planet's atmosphere. 'If we want to claim biosignatures, we need to be extremely sure.'

What this new work shows is that 'the strength of the evidence depends on the nitty gritty details of how we interpret the data, and that doesn't pass the bar for me for a convincing detection,' says Laura Kreidberg, an expert on the atmospheres of distant planets at the Max Planck Institute for Astronomy in Germany who didn't work on the original research team or this new analysis.

She explains that astronomers can make a lot of different choices when analyzing data; for example, they can make different assumptions about the physics and chemistry at play. 'Ideally, for a robust detection, we want it to be model-independent,' she says -- that is, they want the signal to show up even if the underlying assumptions change from one analysis to another. But that wasn't the case here.

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