The Peculiar Type II Supernova 1997D: A Case for a Very Low [TSUP]56[/TSUP]N[CLC]i[/CLC] Mass
Year: 1998
Type: article
Abstract: SN 1997D in NGC 1536 is possibly the least luminous and energetic Type II supernova discovered to date. The entire light curve is subluminous, never reaching M V =-14.65. The radioactive tail follows the 56 Co decay slope. In the case of a nearly complete trapping of the γ-rays, the 56 Ni mass derived from the tail brightness is extremely small, ~0.002 M ☉ . At discovery, the spectra showed a red continuum and line velocities on the order of 1000 km s −1 . The luminosity and the photospheric expansion velocity suggest that the explosion occurred about 50 days before discovery and that a plateau probably followed. Model light curves and spectra of the explosion of a 26 M ☉ star successfully fitted the observations. Low-mass models are inconsistent with the observations. The radius of the progenitor, constrained by the prediscovery upper limits, is R 0 ≲ 300 R ☉ . A low explosion energy of ~4 × 10 50 ergs is then required in the modeling. The strong Ba II lines in the photospheric spectra are reproduced with a solar abundance and low T eff . A scenario in which the low 56 Ni mass observed in SN 1997D is due to fallback of material onto the collapsed remnant of the explosion of a 25-40 M ☉ star appears to be favored over the case of the explosion of an 8-10 M ☉ star with low 56 Ni production.
Source: The Astrophysical Journal
DOI: 10.1086/311324
Institutions: European Southern Observatory, University of California, Santa Barbara, European Southern Observatory, Osservatorio Astronomico di Padova, Kavli Institute for Theoretical Physics, Trieste Astronomical Observatory, National Astronomical Observatory of Japan, The University of Tokyo, Research Center for the Early Universe, Space Telescope Science Institute, Cerro Tololo Inter-American Observatory, Pontificia Universidad Católica de Chile, University of Chile
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W1710955822