Bibcode
DOI
Smartt, S. J.; Vreeswijk, P. M.; Ramirez-Ruiz, E.; Gilmore, G. F.; Meikle, W. P. S.; Ferguson, A. M. N.; Knapen, J. H.
Bibliographical reference
The Astrophysical Journal, Volume 572, Issue 2, pp. L147-L151.
Advertised on:
6
2002
Journal
Citations
51
Refereed citations
39
Description
This Letter presents wide-field optical and near-IR
(UBVRIHαK') images of the galaxy M74 that were taken
between 0.6 and 8.3 yr before the discovery of the Type Ic supernova
2002ap. We have located the position of the supernova on these images
with an accuracy of 0.3". We find no sign of a progenitor object on any
of the images. The deepest of these images is the B-band exposure, which
has a sensitivity limit corresponding to an absolute magnitude of
MB<=-6.3. From our observed limits, we rule out as the
progenitor all evolved states of single stars with initial masses
greater than 20 Msolar unless the W-R phase has been entered.
Two popular theories for the origin of Type Ic supernovae are the core
collapse of massive stars when they are in the W-R phase or the core
collapse of a massive star in an interacting binary that has had its
envelope stripped through mass transfer. Our prediscovery images would
be sensitive only to the most luminous ~30% of W-R stars, hence leaving
a substantial fraction of typical W-R stars as viable progenitors. The
energetics measured from modeling the initial light curve and spectral
evolution of SN 2002ap suggest an explosion of a 5 Msolar C+O
core. While W-R stars generally have measured final masses greater than
this, the uncertainties associated with the explosion model, stellar
evolutionary calculations, and mass measurements suggest we cannot
definitively rule out a W-R star progenitor. The alternative scenario is
that the progenitor was a star of initial mass ~20-25 Msolar
that was part of an interacting binary and stripped of its hydrogen and
helium envelope via mass transfer. We discuss future observations of the
supernova environment that will provide further constraints on the
nature of the progenitor star.