Scientific Seminars

Type Ia SNe and SN 2004dt

Giuseppe Altavilla
INAF-OA Bologna

2008-03-05    14:00    Brera -

Type Ia supernovae (SNe Ia) are thermonuclear explosions of white dwarfs mostly originating from ignition of carbon close to the center of the star when it approaches the Chandrasekhar mass due to accretion of matter from a close binary companion. I will give an overview of Type Ia Supernovae in general, illustrating some of their observational properties and discussing some aspects (and caveats) of their calibration and use as standard candles. After this introduction will present the case of SN 2004dt, which has been extensively observed within the scientific project: "The Physics of Type Ia Supernova Explosions, a European Research Training Network" (RTN), carried out by the European Supernova Collaboration (ESP). I will present the optical spectroscopic properties of SN 2004dt at early epochs. SN 2004dt is a peculiar type Ia SN that differs from most "normal" SNe Ia with respect to line velocities (and shapes). These peculiar features may be explained by rising finger-like structures and clumps produced in the burning, that suggest aspherical explosion scenarios. The availability of early SNe Ia spectra, whose number is increasing thanks to observational efforts, such as the ones performed by the European Supernova Collaboration, shows that some "peculiarities" such as the high-velocity line features observed in SN 2004dt are quite common in SNe Ia when observed in details from the very early phases.