Theoretical predictions for Balmer decrements: (left) – optically thick (dashed) and optically thin (dotted) gas in LTE and observed flux ratios for DENIS 1048-3956. For both the optically thick and the optically thin case, the model with the temperature that best fits the observed decrements is highlighted as a thick line. (Right) – grid of temperature and electron density for a recombining hydrogen plasma. Models compatible with the observed Balmer decrements of DENIS 1048-3956 are marked by large colored symbols: blue diamonds (Hα/Hβ) and red asterisks (the higher-n decrements).