Accession Number:

ADA461939

Title:

OSSE Observations of 57Co In SN1987A

Descriptive Note:

Corporate Author:

NAVAL RESEARCH LAB WASHINGTON DC

Report Date:

1992-01-01

Pagination or Media Count:

9.0

Abstract:

The Oriented Scintillation Spectrometer Experiment OSSE on the COMPTON Gamma Ray Observatory has observed SN1987A for two 2-week periods during the first nine months of the mission. Evidence for gamma-ray line and continuum emission from 57Co is observed with an intensity of about 10exp-4 gamma-sq cm sexp -1. This photon flux between 50 and 136 keV is demonstrated by Monte Carlo calculations to be independent of the radial distribution of the 57Co for models of low optical depth viz., models having photoelectric absorption losses of 122 keV photons no greater than several percent. For such models the observed 57Co flux indicates that the ratio of 57Ni56Ni produced in the explosion was about 1.5 times the solar system ratio of 57Fe56Fe. When compared with nearly contemporaneous bolometric estimates of the luminosity for SN1987A, our observations imply that 57Co radioactivity does not account for most of the current luminosity of the supernova remnant in low-optical-depth models. We suggest alternatives including a large-optical-depth model that is able to provide the SN1987A luminosity and is consistent with the OSSE flux. It requires a 5756 production ratio of about twice solar.

Subject Categories:

  • Astronomy
  • Nuclear Physics and Elementary Particle Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE