http://arxiv.org/abs/1704.07443
Observations of the Earth’s exosphere have unveiled an extended envelope of hydrogen reaching further than 10 Earth radii (R$_E$) composed of atoms orbiting around the Earth. This large envelope increases significantly the opacity of the Earth to Lyman-alpha (Lya) photons coming from the Sun, to the point of making feasible to detect the Earth’s transit signature from 1.35 pc with an 8~meter primary mirror space telescope, as we show. In this work, we evaluate the potential detectability of Earth analogues orbiting around nearby M-type stars by monitoring the Lya flux variability. We show that, in spite of the interstellar, heliospheric and astrospheric absorption, transits in M-type stars would be detectable with a 4-8 m class telescope. A 2-m class telescope, such as the World Space Observatory would suffice to detect an Earth-like planet orbiting around Proxima Centauri. Such monitoring program would enable measuring the robustness of planetary atmospheres under heavy space weather conditions like those produced by M-type stars.
A. Castro, L. Beitia-Antero and S. Ustamujic
Wed, 26 Apr 17
60/60
Comments: submitted to Experimental Astronomy, 5 figures