Effect of stellar flares on the upper atmospheres of HD 189733b and HD 209458b J. M. Chadney, T. T. Koskinen, M. Galand, Y. C. Unruh and J. Sanz-Forcada A&A, 608 (2017) A75 Published online: 08 December 2017 DOI: 10.1051/0004-6361/201731129