Depletion and low gas temperature in the L183 (=L134N) prestellar core: the N2H+–N2D+ tool L. Pagani, A. Bacmann, S. Cabrit and C. Vastel A&A, 467 1 (2007) 179-186 Published online: 05 March 2007 DOI: 10.1051/0004-6361:20066670