Earth-sized planets could be habitable01/09/17Science & Technology
According to an international team of researchers, there could be water on multiple Earth-sized planets orbiting the recently discovered TRAPPIST-1 dwarf star.
Using the NASA/ESA Hubble telescope to estimate whether there may be water on the surface of the seven planets around TRAPPIST-1, the researchers found that although the innermost planets must have lost most – if not all – of their water, the outer planets of the system may still harbour substantial amounts.
The researchers measured the ultraviolet (UV) irradiation that the planets receive from TRAPPIST-1, as these UV rays cause water molecules to break apart into their constituent hydrogen and oxygen atoms.
Professor Peter Wheatley, from the University of Warwick, UK, played a significant role in the project, measuring the X-ray irradiation of the planets by their parent star.
The observed amount of ultraviolet radiation emitted by TRAPPIST-1 suggests that the planets could have lost large amounts of water over the course of their history.
However, the outer planets of the system — including the planets e, f and g which are in the habitable zone — should have lost much less water, suggesting that they could have retained some on their surfaces.
Wheatley said: “It is exciting that we can now study the environments of individual Earth-sized planets. Our results suggest that water, and potentially Life, could have survived in the TRAPPIST-1 system, despite the relatively intense ultraviolet and X-ray irradiation of the planets.”
This study was led by the Swiss astronomer Vincent Bourrier from the Observatoire de l’Université de Genève.