A multi-wavelength analysis of M 81: insight on the nature of Arp's loopA. Sollima, A. Gil de Paz, D. Martinez-Delgado, R. J. Gabany, J. J. Gallego-Laborda and T. HallasA&A, 516 (2010) A83DOI: https://doi.org/10.1051/0004-6361/201014085