Supernova 1987A: The envelope mass and the explosion energy

Abstract

Our study of the photometric and spectroscopic observations of SN 1987A based on the hydrodynamic modeling of its bolometric light curve and nonstationary hydrogen kinetics and energy balance when modeling the hydrogen spectral lines at the photospheric stage has shown that good agreement with the observations can be achieved only at a ratio of the explosion energy to the ejected-envelope mass of ≈0.83 × 1050 erg M ⊙ −1 . In this case, the radius of the presupernova is 35.0 ± 5R⊙, and the surface chemical composition is typical of the LMC with the mass fractions of hydrogen X = 0.743, helium Y = 0.251, and heavy elements Z = 0.006. The analyzed dependence of the bolometric light curve on the mass of the ejected envelope at the above ratio of the explosion energy to the envelope mass suggests that the optimal mass is 18.0M ⊙ with an admissible spread of ±1.5M ⊙, and, accordingly, the explosion energy of SN 1987A is (1.50 ± 0.12) × 1051 erg. If a neutron star with a mass of ≈1.6M ⊙ was formed through the gravitational collapse of an iron stellar core, then the mass of the presupernova immediately before the explosion of SN 1987A was 19.6 ± 1.5M ⊙.