G345.45+1.50: an expanding ring-like structure with massive star formation Cristian López-Calderón, Leonardo Bronfman, Lars-Åke Nyman, Guido Garay, Itziar de Gregorio-Monsalvo and Per Bergman A&A, 595 (2016) A88 Published online: 03 November 2016 DOI: 10.1051/0004-6361/201321696