Signatures of volcanic satellites orbiting WASP-49b

https://www.unibe.ch/news/media_news/media_relations_e/media_releases/2019/medienmitteilungen_2019/hints_of_a_volcanically_active_exomoon/index_eng.html

Hints of a volcanically active exomoon

A rocky extrasolar moon (exomoon) with bubbling lava may orbit a planet 550 light-years away from us. This is suggested by an international team of researchers led by the University of Bern on the basis of theoretical predictions matching observations. The “exo-Io” would appear to be an extreme version of Jupiter’s moon Io.

Paper here:
https://arxiv.org/abs/1908.10732

They note that WASP-49b's transmission spectroscopy could be explained by such a moon.