Free Astronomy Magazine

EXOPLANETS sit. In particular, we must be able to ex- clude the possibility that a companion star partially eclipses the primary, or that a background vari- able star contami- nates the light curve of Kepler-186. Just to dispel any doubt, the team led by Quintana has car- ried out observa- tions at high spatial resolution in the im- mediate area sur- rounding the red dwarf. Using the speckle imaging technique with the Gemini telescope, they were able to move – in the visible range – as far as 4.2 astronomical units (AU) toward the star without finding any suspicious object; a result achieved also in the infrared with the Keck II (fitted with the Natural Guide Star Adaptive Optics system and the Near-Infrared Cam- era 2). The images obtained with the two telescopes have allowed to conclude that there are 99.98 chances out of 100 that Kepler-186f re- T he diagram on the left, besides providing a scale of the or- bits of Kepler-186 planets, compares the habitable zones (in gray) of four planetary systems, showing the amount of energy received from the various planets (Earth = 1). [S. Raymond/E. BOLMONT et al.] Below: Elisa Quintana, the re- search scientist who, with about twenty colleagues, confirmed the existence of Ke- pler-186f. The re- sults of the work were published in the April journal Science. ally exists. The remaining 0.02% is the prob- ability that a very small companion star exists at between 1.4 and 4.2 AU from Ke- pler-186. At distances below 1.4 AU there cannot be anything significant as the plan- etary system would not otherwise be as stable as it appears – a stability which has lasted several billion years (8-10 and maybe more). Having ascertained that Kepler-186f exists, the researchers then attempted to under- stand the extent to which it is similar to Earth. Its location towards the outer edge of the habitable zone guarantees to it about 1/3 of the energy that our planet