Smooth X-ray variability from ρ Ophiuchi A+B - A strongly magnetized primary B2 star? Ignazio Pillitteri, Scott J. Wolk, Alyssa Goodman and Salvatore Sciortino A&A, 567 (2014) L4 Published online: 04 July 2014 DOI: 10.1051/0004-6361/201424243