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Astron. Astrophys. 354, 557-566 (2000)


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The nature of SN 1997D: low-mass progenitor and weak explosion *

Nikolai N. Chugai 1,2 and Victor P. Utrobin 3,4

1 Institute of Astronomy RAS, Pyatnitskaya 48, 109017 Moscow, Russia
2 European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
3 Institute of Theoretical and Experimental Physics, B. Cheremushkinskaya St. 25, 117259 Moscow, Russia
4 Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Strasse 1, 85740 Garching, Germany

Received 11 June 1999 / Accepted 23 November 1999

Abstract

We analyzed the spectra and light curve of the peculiar type II-P supernova 1997D to recover ejecta parameters. The optimal hydrodynamical model of SN 1997D, which meets observational constraints at the photospheric epoch, suggests a low explosion energy of about [FORMULA] erg, ejecta mass around [FORMULA], and presupernova radius near [FORMULA]. We confirm the previous result by Turatto et al. (1998) that the ejecta contain a very low amount of radioactive 56Ni ([FORMULA]). Modelling the nebular spectrum supports the hydrodynamical model and permits us to estimate the mass of freshly synthesized oxygen (0.02-0.07 [FORMULA]). Combined with the basic results of stellar evolution theory the obtained parameters of SN 1997D imply that the progenitor was a star from the 8-12 [FORMULA] mass range at the main sequence. The fact that at least some progenitors from this mass range give rise to core-collapse supernovae with a low kinetic energy ([FORMULA] erg) and low amount of radioactive 56Ni ([FORMULA]) has no precedent and imposes important constraints on the explosion mechanism. We speculate that the galactic supernovae 1054 and 1181 could be attributed to SN 1997D-like events.

Key words: supernovae: general – supernovae: individual: SN 1997D – ISM: supernova remnants

* All the SN 1997D spectra used in this paper were kindly provided by Massimo Turrato

Send offprint requests to: N.N. Chugai (nchugai@inasan.rssi.ru)

© European Southern Observatory (ESO) 2000

Online publication: February 9, 2000

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