Relative magnetic helicity as a diagnostic of solar eruptivity E. Pariat, J. E. Leake, G. Valori, M. G. Linton, F. P. Zuccarello and K. Dalmasse A&A, 601 (2017) A125 Published online: 17 May 2017 DOI: 10.1051/0004-6361/201630043