## Abstract

We revisit the evidence for the contribution of the long-lived radioactive nuclides ^{44}Ti, ^{55}Fe, ^{56}Co, ^{57}Co, and ^{60}Co to the UVOIR light curve of SN 1987A. We show that the V-band luminosity constitutes a roughly constant fraction of the bolometric luminosity between 900 and 1900 days, and we obtain an approximate bolometric light curve out to 4334 days by scaling the late time V-band data by a constant factor where no bolometric light curve data is available. Considering the five most relevant decay chains starting at ^{44}Ti, ^{55}Co, ^{56}Ni, ^{57}Ni, and ^{60}Co, we perform a least squares fit to the constructed composite bolometric light curve. For the nickel isotopes, we obtain best fit values of M(^{56}Ni) = (7.1 ± 0.3) × 10 ^{-2} M _{⊙} and M(^{57}Ni) = (4.1 ± 1.8) × 10^{-3} M _{⊙}. Our best fit ^{44}Ti mass is M(^{44}Ti) = (0.55 ± 0.17) × 10^{-4} M _{⊙}, which is in disagreement with the much higher (3.1 ± 0.8) × 10^{-4} M _{⊙} recently derived from INTEGRAL observations. The associated uncertainties far exceed the best fit values for ^{55}Co and ^{60}Co and, as a result, we only give upper limits on the production masses of M(^{55}Co) < 7.2 × 10^{-3} M _{⊙} and M(^{60}Co) < 1.7 × 10^{-4} M _{⊙}. Furthermore, we find that the leptonic channels in the decay of ^{57}Co (internal conversion and Auger electrons) are a significant contribution and constitute up to 15.5% of the total luminosity. Consideration of the kinetic energy of these electrons is essential in lowering our best fit nickel isotope production ratio to [^{57}Ni/^{56}Ni] = 2.5 ± 1.1, which is still somewhat high but is in agreement with gamma-ray observations and model predictions.

Original language | English |
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Article number | 10 |

Journal | Astrophysical Journal |

Volume | 792 |

Issue number | 1 |

DOIs | |

Publication status | Published - 1 Sept 2014 |