Optical and infrared observations of SN 2002dj: some possible common properties of fast-expanding Type Ia supernovae |
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| Authors: | G Pignata S Benetti P A Mazzali R Kotak F Patat P Meikle M Stehle B Leibundgut N B Suntzeff L M Buson E Cappellaro A Clocchiatti M Hamuy J Maza J Mendez P Ruiz-Lapuente M Salvo B P Schmidt M Turatto W Hillebrandt |
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| Institution: | Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile;Departamento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22, Chile;INAF Osservatorio Astronomico di Padova, Vicolo dell Osservatorio 5, I-35122 Padova, Italy;Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching bei München, Germany;Osservatorio Astronomico di Trieste, Via Tiepolo 11, I-34131 Trieste, Italy;Astrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN;European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei München, Germany;Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW;Department of Physics, Texas A&M University, College Station, TX 77843-4242, USA;Department of Astronomy, University of Barcelona, Marti i Franques 1, E-08028 Barcelona, Spain;Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston Creek, ACT 2611, Australia |
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| Abstract: | As part of the European Supernova Collaboration, we obtained extensive photometry and spectroscopy of the Type Ia supernova (SN Ia) SN 2002dj covering epochs from 11 d before to nearly two years after maximum. Detailed optical and near-infrared observations show that this object belongs to the class of the high-velocity gradient events as indicated by Si, S and Ca lines. The light curve shape and velocity evolution of SN 2002dj appear to be nearly identical to SN 2002bo. The only significant difference is observed in the optical to near-infrared colours and a reduced spectral emission beyond 6500 Å. For high-velocity gradient SNe Ia, we tentatively identify a faster rise to maximum, a more pronounced inflection in the V and R light curves after maximum and a brighter, slower declining late-time B light curve as common photometric properties of this class of objects. They also seem to be characterized by a different colour and colour evolution with respect to 'normal' SNe Ia. The usual light curve shape parameters do not distinguish these events. Stronger, more blueshifted absorption features of intermediate-mass elements and lower temperatures are the most prominent spectroscopic features of SNe Ia displaying high-velocity gradients. It appears that these events burn more intermediate-mass elements in the outer layers. Possible connections to the metallicity of the progenitor star are explored. |
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| Keywords: | supernovae: general supernovae: individual: SN 2002dj |
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