# Strong effects of time-dependent ionization in early SN 1987A Source: [Strong effects of time-dependent ionization in early SN 1987A]() Collection index: [llms.txt]() Data updated: 2025-10-27T03:05:26.850Z Authors: V. P. Utrobin, N. N. Chugai (3) \_\_INSTITUTION\_2\_\_ Max-Planck-Institut fuer Astrophysik, Germany; (2) Institute of Theoretical, Experimental Physics, Russia; (3) Institute of Astronomy of Russian Academy of Sciences, Russia) Published: 2005-01-04T10:31:10.000Z ## Abstract We study a time-dependent hydrogen ionization in the atmosphere of SN 1987A during the first month after the explosion. The model includes kinetics of hydrogen ionization and excitation, molecular hydrogen kinetics, and a time-dependent energy balance. The primary strong effect of the time-dependent ionization is the enhanced hydrogen ionization compared to the steady-state model. The time-dependent ionization provides a sufficient population of excited hydrogen levels to account for the observed H-alpha without invoking the external Ni-56. We find that the Ba II 6142 A line in SN 1987A can be reproduced for the LMC barium abundance. This resolves the long-standing problem of the unacceptably high barium overabundance in SN 1987A. The key missing factor that should be blamed for the "barium problem" is the time-dependent ionization. The modelling of the H-alpha profile on day 4.64 indicates the ratio of the kinetic energy to the ejected mass about 0.83 10^{50} erg/Msun. ## Recorded benchmark results A research result applies to its stated dataset, split, metric and evaluation configuration. Compare like-for-like settings, preserve the metric's unit and direction, and distinguish paper-reported results from independent reproduction. The best result recorded here is not a claim of exhaustive, current global coverage. ## Original sources and implementation [Original paper]() [PDF]()