First stars of the ρ Ophiuchi dark cloud - XMM-Newton view of ρ Oph and its neighbors I. Pillitteri, S. J. Wolk, H. H. Chen and A. Goodman A&A, 592 (2016) A88 Published online: 04 August 2016 DOI: 10.1051/0004-6361/201628284