Red supergiants around the obscured open cluster Stephenson 2 I. Negueruela, A. Marco, C. González-Fernández, F. Jiménez-Esteban, J. S. Clark, M. Garcia and E. Solano A&A, 547 (2012) A15 Published online: 19 October 2012 DOI: 10.1051/0004-6361/201219540