Size matters in the detection of exoplanet atmospheres

A group-analysis of 30 exoplanets orbiting distant stars suggests that size, not mass, is a key factor in whether a planet's atmosphere can be detected according to a UCL-led team of European researchers. The largest population-study of exoplanets to date successfully detected atmospheres around 16 'hot Jupiters', and found that water vapour was present in every case. The findings, presented today at the European Planetary Science Congress , have important implications for the comparison and classification of diverse exoplanets. "More than 3,000 exoplanets have been discovered but, so far, we've studied their atmospheres largely on an individual, case-by-case basis. Here, we've developed tools to assess the significance of atmospheric detections in catalogues of exoplanets," said Angelos Tsiaras, the lead author of the study and PhD student in UCL Physics & Astronomy. "This kind of consistent study is essential for understanding the global population and potential classifications of these foreign worlds." The researchers used archive data from the ESA/NASA Hubble Space Telescope's Wide Field Camera 3 (WFC3) to retrieve spectral profiles of 30 exoplanets and analyse them for the characteristic fingerprints of gases that might be present. About half had strongly detectable atmospheres.