A search for the progenitors of two Type Ia Supernovae in NGC 1316 |
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Authors: | Dan Maoz Filippo Mannucci |
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Affiliation: | School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel;INAF –Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, Florence 50125, Italy;INAF –Istituto di Radioastronomia, Largo Enrico Fermi 5, Florence 50125, Italy |
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Abstract: | Recent evidence of a young progenitor population for many Type Ia supernovae (SNe Ia) raises the possibility that evolved intermediate-mass progenitor stars may be detected in pre-explosion images. NGC 1316, a radio galaxy in the Fornax cluster, is a prolific producer of SNe Ia, with four detected since 1980. We analyse Hubble Space Telescope ( HST ) pre-explosion images of the sites of two of the SNe Ia that exploded in this galaxy, SN2006dd (a normal Type Ia) and SN2006mr (likely a subluminous, 1991bg-like, SN Ia). Astrometric positions are obtained from optical and near-infrared ground-based images of the events. We find no candidate point sources at either location, and set upper limits on the flux in B, V and I from any such progenitors. We also estimate the amount of extinction that could be present, based on analysis of the surface-brightness inhomogeneities in the HST images themselves. At the distance of NGC 1316, the limits correspond to absolute magnitudes of ∼−5.5, −5.4 and −6.0 mag in M B , M V and M I , respectively. Comparison to stellar evolution models argues against the presence at the supernova sites, 3 yr prior to the explosion, of normal stars with initial masses ≳6 M⊙ at the tip of their asymptotic-giant branch (AGB) evolution, young post-AGB stars that had initial masses ≳4 M⊙ and post-red giant stars of initial masses ≳9 M⊙ . |
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Keywords: | supernovae: general supernovae: individual: SN2006dd supernovae: individual: SN2006mr galaxies: individual: NGC 1316 |
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