(Phys.org)—Astronomers have detected the presence of water molecules in the atmosphere of a nearby hot Jupiter exoplanet known as 51 Pegasi b (51 Peb b for short). The discovery sheds new light on the nature of the exoworld’s atmosphere and indicates that the star-planet system is a double-lined spectroscopic binary. The findings were presented Jan. 25 in a paper published on arXiv.org.