Carola I. Ellinger

Collateral Effects on Solar Nebula Oxygen Isotopes Due to Injection of 26Al by a Nearby Supernova

Injection of material from a core-collapse supernova into the solar systems already-formed disk is one proposed mechanism for producing the short-lived radionuclides, such as 26Al? and 41Ca, inferred from isotopic studies of meteorites to have existed in the solar nebula. This hypothesis has recently been challenged on the basis that the injection of enough supernova material to match the meteoritic abundances of 26Al and 41Ca would produce large, measurable, and unobserved collateral effects on oxygen isotopes. Here we calculate again the shifts in oxygen isotopes due to the injection of supernova material in the solar nebula, using a variety of nucleosynthetic conditions of our own progenitor explosions. Unlike previous studies of this type, we also consider the effect of non-homogeneity in abundance distribution of the nucleosynthesis products after the explosion. We calculate the shifts in oxygen isotopes due to the injection of sufficient supernova material to produce the meteoritic abundances of 26Al and 41Ca, and analyze the predicted shifts in detail for compatibility with meteoritic data. We find that the range in possible isotopic shifts is considerable and sensitive to parameters such as progenitor mass and anisotropy of the explosion; however, a small number of compatible scenarios do exist. Because of the wide range of outcomes and the sensitivity of isotopic yields to assumed conditions, it is difficult to constrain the supernova that may have led to the injection of 26Al in the solar nebula. Conversely, we argue that the existence of viable counterexamples demonstrates that it is premature to use oxygen isotopes to rule out the injection of 26Al and 41Ca into the solar nebula protoplanetary disk by a nearby supernova.

Finding Tracers for Supernova Produced 26Al

We consider the cospatial production of elements in supernova explosions to find observationally detectable proxies for enhancement of 26Al in supernova ejecta and stellar systems. Using four progenitors, we explore a range of one-dimensional explosions at different energies and an asymmetric three-dimensional explosion. We find that the most reliable indicator of the presence of 26Al in unmixed ejecta is a very low S/Si ratio (~0.05). Production of N in O/S/Si-rich regions is also indicative. The biologically important element P is produced at its highest abundance in the same regions. Proxies should be detectable in supernova ejecta with high spatial resolution multiwavelength observations, but the small absolute abundance of material injected into a proto-planetary disk makes detection unlikely in existing or forming stellar/planetary systems.

Spatial Distribution of Nucleosynthesis Products in Cassiopeia A: Comparison Between Observations and 3D Explosion Models

We examine observed heavy element abundances in the Cassiopeia A supernova remnant as a constraint on the nature of the Cas A supernova. We compare bulk abundances from 1D and 3D explosion models and spatial distribution of elements in 3D models with those derived from X-ray observations. We also examine the cospatial production of 26Al with other species. We find that the most reliable indicator of the presence of 26Al in unmixed ejecta is a very low S/Si ratio (~0.05). Production of N in O/S/Si-rich regions is also indicative. The biologically important element P is produced at its highest abundance in the same regions. Proxies should be detectable in supernova ejecta with high spatial resolution multiwavelength observations.

Nucleosynthetic Constraints on the Progenitor of Cassiopeia A

Our recent 3D simulation of a supernova explosion to constrain the progenitor of Cas A has enabled us to gain new insight into burning processes at work. Of special interest in this poster are the isotopes 26Al, 16O, 17O, and 18O. These isotopes are important in the formation history of our solar system, and help constrain its environment at the time of formation. A favored model is the addition of supernova ejecta to the forming solar system, which presumably changed the isotopic abundances of a range of isotopes (like those mentioned above). In this poster we investigate how the relative abundances of the oxygen isotopes in the solar system is affected by the injection of supernova material, given that this injection produces the expected change in 26Al/27Al. We also investigate whether the bulk composition or specific zones of the supernova are more appropriate, and what the determining factors are. Lastly, we look at differences between 1D and the 3D simulation in this matter.