Three-dimensional mixing and light curves: constraints on the progenitor of supernova 1987A^⋆

¹ Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching, Germany
² State Scientific Center of the Russian Federation – Institute for Theoretical and Experimental Physics of National Research Center “Kurchatov Institute”, B. Cheremushkinskaya St. 25, 117218 Moscow, Russia
e-mail: utrobin@itep.ru
³ Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064, USA

Received: 24 December 2018
Accepted: 4 March 2019

Abstract

With the same method as used previously, we investigate neutrino-driven explosions of a larger sample of blue supergiant models. The blue supergiants were evolved as single-star progenitors. The larger sample includes three new presupernova stars. The results are compared with light-curve observations of the peculiar type IIP supernova 1987A (SN 1987A). The explosions were modeled in 3D with the neutrino-hydrodynamics code PROMETHEUS-HOTB, and light-curve calculations were performed in spherical symmetry with the radiation-hydrodynamics code CRAB, starting at a stage of nearly homologous expansion. Our results confirm the basic findings of the previous work: 3D neutrino-driven explosions with SN 1987A-like energies synthesize an amount of ⁵⁶Ni that is consistent with the radioactive tail of the light curve. Moreover, the models mix hydrogen inward to minimum velocities below 400 km s⁻¹ as required by spectral observations and a 3D analysis of molecular hydrogen in SN 1987A. Hydrodynamic simulations with the new progenitor models, which possess smaller radii than the older ones, show much better agreement between calculated and observed light curves in the initial luminosity peak and during the first 20 days. A set of explosions with similar energies demonstrated that a high growth factor of Rayleigh–Taylor instabilities at the (C+O)/He composition interface combined with a weak interaction of fast Rayleigh–Taylor plumes, where the reverse shock occurs below the He/H interface, provides a sufficient condition for efficient outward mixing of ⁵⁶Ni into the hydrogen envelope. This condition is realized to the required extent only in one of the older stellar models, which yielded a maximum velocity of around 3000 km s⁻¹ for the bulk of ejected ⁵⁶Ni, but failed to reproduce the helium-core mass of 6 M_⊙ inferred from the absolute luminosity of the presupernova star. We conclude that none of the single-star progenitor models proposed for SN 1987A to date satisfies all constraints set by observations.