Probing Supernova Dynamics and Nucleosynthesis with STARDUST by hcj


									Probing Supernova Dynamics and Nucleosynthesis with STARDUST Don Clayton Seattle July 16, 2004 I. INTRODUCTION. Stan Woosley was a research student at Rice University 35 years ago when the program that I report began, and he has been a key player in it ever since. That program can be described as "the observables from SN that reveal their structure and dynamics". Stan started down the path of nucleosynthesis, which depends for t=1s on structure and dynamics (as well as on preSN evolution). But in the same year we began noting observables that depend on structure at 107 s. gamma-ray lines hard X-ray continuum high-excitation lines (He+, etc.) supernova light curves spectroscopic imaging of young remnant Indeed, Stan's first paper (1969) argued that the high isotopic abundance of 58Ni implies that 56Fe was synthesized as 56Ni, implying a bright future for 56Ni radioactivity. II. SUNOCONs. Beginning in 1975 (Nature and ApJ) I have predicted a newer observable of supernova structure and dymanics; namely, the supernova condensates (SUNOCON) that are a part of the presolar STARDUST. The SUNOCON were present in the ISM, and are still found today preserved in the meteorites (and comets and IDPs). Two general references are recommended: D. Clayton & N. Nittler, Annual Reviews Astron. Astrophys., 2004 D. Clayton, Handbook of Isotopes in the Cosmos, Camb. Univ Press, 2003 A SUNOCON is a solid piece of a supernova! It is absolutely sensational that we can hold them in our hands on earth, and study them in laboratories. View 1. An X grain of SiC and a mainstream grain of SiC. SEM photo. View 2. Isotopic composition of Ca in a large graphite onion. Note huge 44Ca excess. View 3. The initial 44Ti/48Ti ratio in SUNOCON Why do we find SiC with similar composition to graphite? What enables SiC to condense rather than graphite? And why are they mildly 28Si-rich? Many papers about documenting the particles have written incorrectly about the answers to these important questions. They appeal to unspecified mixings at molecular gas levels to condense these particles; but we find that better answers depend in exciting ways on SN structure and dynamics! (Deneault, Clayton & Heger ApJ 2003). View 4. Reverse shock from H and the SiC region. Momentum flux from reverse shock compresses the interior between m= 2.6 and 3.6 solar masses.

View 5. SiC structure function (Inner part is 28Si-rich, outer part is 30Si-rich). This product of Si and C number densities is proportional to the rate of formation of SiC molecules. View 6. Why SiC instead of graphite? Si/C ratio gives the answer. To get SiC the composition must have more Si than C, by a factor ten or more. This selects those inner Supernova zones for which it is true. View 7. Why 28Si-rich? SiC condenses inside m=3. Although part of the structure function (View 5) is 29,30Si-rich, that part condenses graphite. The region wherein Si/C > 10 is 28Si-rich. This explains the observed property of SiC X grains.

III. DYNAMICS AND MICROSCOPIC QUANTITES. The interplay between SN dynamics and measurable physical quantities can be illustrated by a simplified calculation: Condensation in a gas composed of C+O (only). Physical model parameters: 1. entropy, which we measure by the density at 2000K (near t=107 s) 2. The element abundance ratio C/O 3. The radioactivity energy deposition rate (56Co abundance)

Dependence of SUNOCONs (graphite in this case) on microscopic quantities: I will run through a series of figures, explaining each. A paper detailing these results will appear in ApJ by Deneault, Clayton & Meyer (2005). View 8. View 9. View 10. View 11. View 12. View 13. View 14. View 15. 4.1. Linear Chain abundances depend on C/O Fraction of C in CO without CO destruction Showing dependence on rate for C+O > CO Results of CO breakup, thermal and radioactive Dust atom fractions/bin for different C/O ratios Dust atom fractions/bin for different isomerizing chain j=10, 14, 16 Dust atom fractions/bin for different C association rate factors with grains Dust atom fractions/bin for different 56Co yields of the SN

To top