180 likes | 277 Views
INAF. The massive zero metal stars: their evolutionary properties and their explosive yields. Alessandro Chieffi Istituto Nazionale di AstroFisica (Istituto di Astrofisica Spaziale e Fisica Cosmica) & Centre for Stellar and Planetary Astrophysics – Monash University - Australia
E N D
INAF The massive zero metal stars: their evolutionary properties and their explosive yields. Alessandro Chieffi Istituto Nazionale di AstroFisica (Istituto di Astrofisica Spaziale e Fisica Cosmica) & Centre for Stellar and Planetary Astrophysics – Monash University - Australia Email: achieffi@rm.iasf.cnr.it Marco Limongi Istituto Nazionale di AstroFisica (Osservatorio Astronomico di Roma) & Centre for Stellar and Planetary Astrophysics – Monash University - Australia Email: marco@mporzio.astro.it
The “metallicity” influences the physical evolution of a star: CNO T of H burning Fe + a elements k (opacity) Mass Loss depends on Z ZERO METALLICITY STARS FREQUENTLY SHOW THE MERGING OF THE H AND HE RICH LAYERS!
8.5 Log10(T) Log10(X) 7.5 M(MO)
The “metallicity” influences the yields provided by a star: 25Mg & n CNO Odd-even effect Initial isotopic distribution (seeds) Neutron excess h (affects the explosive burnings) The weak s-component
35Cl 37Cl 32S 33S 34S 36S 31P 28Si 29Si 30Si 27Al 24Mg 25Mg 26Mg P 23Na 20Ne 21Ne 22Ne 19F 16O 17O 18O 14N 15N 12C 13C N
35Cl 37Cl 32S 33S 34S 36S 31P 28Si 29Si 30Si 27Al 24Mg 25Mg 26Mg P 23Na 20Ne 21Ne 22Ne 19F 16O 17O 18O 14N 15N 12C 13C N
Co Cu Zn Sc Ti Fe Ni Z=0 Z=ZO
13 15 20 25 30 35
The theoretical yields Grid of 8 stellar models: 13, 15, 20, 25, 30, 35, 50 and 80 MO initial chemical composition: Z=0, Y=0.23 Presupernova evolution computed with the FRANEC (rel. 4- 05.04.19) Nuclear network of 296 nuclei (complete up to Mo) Two alternative set up: Physical + Chemical equations solved simultaneously mixing performed in a successive step through a diffusion equation or Physical equations solved first Local burning and mixing fully coupled together Explosive yields computed by means of a PPM code The energy is injected by imposing an arbitrary velocity to a few mass layers around 1MO
All these yields have been obtained for a specific choice of the Mass Cut Hydrostatic burn. Ox & Siix Ox Six & Siix Six Siix N strongly produced in the range 25 to 40 MO (it depends significantly on the amount of C left by the He burning) Yields often do not show a monotonic dependence on the initial mass [Al/O] in principle could be a initial mass indicator
Mass cut 0.1 56Ni Variable Mass cut
CONCLUSIONS DON’T MISS THE NEXT TALK!