Consequences of Incomplete Carbon Burning in Type Ia Supernovae
Abstract
Type Ia supernovae (SNe Ia) are the explosions of carbon-oxygen white dwarf stars. These events can be improved as cosmological distance indicators by further understanding the details of the explosion physics. As the nuclear flame propagates through the star, it burns carbon/oxygen fuel into iron-group element ash. How much fuel remains unburned after the explosion remains an open question. SNe Ia have very similar peak brightnesses indicating a similar burning process in all objects, yet some SNe Ia have strong carbon absorption in their spectra, while others have none, suggesting a range of efficiencies. We use a relational database of SN Ia spectra (kaepora) to investigate if unburned carbon is linked to other properties of the explosion. We measured the strength of the C II 6280 feature for 1214 spectra of 225 SNe and fit for its evolution over time. Using the strength of the carbon absorption at a common phase, we separate the sample and compare their average spectral properties. We confirm that SNe with stronger carbon features tend to have lower maximum-light Si II 6355 velocities than those with weak or no absorption. We examined the color evolution of the subsamples, finding a subtle difference at t greater than 50 days after peak brightness. We also find that carbon-strong SNe Ia tend to have blueshifted nebular features, pointing to explosion asymmetry as a cause of the difference in carbon strength.
- Publication:
-
American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23527604A