Asymmetry in the triplet 3p-4s Mg lines in cool DZ white dwarfs N. F. Allard, T. Leininger, F. X. Gadéa, V. Brousseau-Couture and P. Dufour A&A, 588 (2016) A142 Published online: 01 April 2016 DOI: 10.1051/0004-6361/201527826