Arcones, A.

Bliss, J.

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Nucleosynthesis of elements between Sr and Ag in neutron- and proton-richneutrino-driven windsJ. Bliss1 and A. Arcones1,21Institut fu¨r Kernphysik, Technische Universita¨t Darmstadt, Darmstadt, Germany; 2GSI Helmholtzzentrum fu¨rSchwerionenforschung GmbH, Darmstadt, GermanyNeutrino-driven winds that follow core collapse super-novae were thought to be the site where half of the heavyelements are produced by the r-process. Although recenthydrodynamic simulations show that the conditions in thewind are not neutron-rich enough for the r-process (see e.g.[7]), lighter heavy elements like Sr, Y and Zr can be pro-duced [1, 8, 4]. However, it is still not clear whether theconditions in the wind are slighly neutron-rich or proton-rich. In Ref. [1], we have studied the formation of lighterheavy elements in slighly neutron-rich (Ye < 0.5) andproton-rich (Ye > 0.5) winds. We have systematically ex-plored the impact of the wind parameters (see e.g. [9, 6]):entropy, expansion time scale and electron fraction Ye. Thewind parameters have been varied within typical conditionsvalues found in wind simulations [2, 3].An overview of the dependency of the Sr abundances onthe wind parameters is shown in Fig. 1. Similar featuresand trends are obtained for other lighter heavy elements(see [1]).In neutron-rich winds (upper panel) the abundances of Sroscillate and exhibit several minima and maxima when thewind parameters are varied. In proton-rich winds (lowerpanel) we find two main differences. First, the abundancesvary smoothly when varying the wind parameters. Depend-ing on the wind parameters the heaviest element that canbe produced changes. The overall abundance pattern re-mains similar for Sr, Y, Zr and Ag. Thus, if neutrino-drivenwinds are responsible for the observed abundances in veryold stars, neutron-rich conditions would not provide the ro-bustness observed in the abundance pattern. Second, mostof the ejected matter consists of protons and alpha particlesin proton-rich winds, while the amount of heavy nuclei issmall (Yseed . 10−4). In neutron-rich winds alpha par-ticles also dominate the composition but heavy nuclei aremore abundant (Yseed > 10−3) than in proton-rich condi-tions. Hence, if every wind stays neutron-rich for severalseconds there would be an overproduction around A=90[5, 10]. Therefore, not every wind can be only neutron-rich.Combining nucleosynthesis studies, like the one here,with new and future experimental data and observations, itwill give rise to new insights about the supernova neutrinosand explosions.This work was funded by the Helmholtz-UniversityYoung Investigator grant No. VH-NG-825.40 50 60 70 80 90 100 110Entropy [kB/nuc]0.400.410.420.430.440.450.460.470.480.49YeSr−8−7−6−5−4−3−2−140 50 60 70 80 90 100 110Entropy [kB/nuc]0.510.520.530.540.550.560.570.580.590.600.610.620.630.640.650.66YeSr−15−14−13−12−11−10−9−8−7−6−5Figure 1: Color contours show the abundance in log scaleof Sr for different entropies and Ye in neutron-rich (upperpanel) and proton-rich (lower panel) winds.References[1] A. Arcones and J. Bliss, J. Phys. G, 41:044005, 2014.[2] A. Arcones and H.-T. Janka. A&A, 526:A160, 2011.[3] A. Arcones, H.-T. Janka, and L. Scheck. A&A, 467:1227–1248, 2007.[4] A. Arcones and F. Montes. ApJ, 731:5, 2011.[5] R. D. Hoffman, S. E. Woosley, G. M. Fuller, and B. S. Meyer.ApJ, 460:478–488, 1996.[6] R. D. Hoffman, S. E. Woosley, and Y.-Z. Qian. ApJ, 482:951–962, 1997.[7] L. Hu¨depohl, B. Mu¨ller, H.-T. Janka, A. Marek, and G. G.Raffelt. Phys. Rev. Lett., 104(25):251101, 2010.[8] Y.-Z. Qian and G. J. Wasserburg. Phys. Rep., 442:237–268,2007.[9] Y.-Z. Qian and S. E. Woosley. ApJ, 471:331–351, 1996.[10] S. E. Woosley and R. D. Hoffman. ApJ, 395:202–239, 1992.MU-THEORY-08 GSI SCIENTIFIC REPORT 2014344 DOI:10.15120/GR-2015-1-MU-THEORY-08

Nucleosynthesis of elements between Sr and Ag in neutron- and proton-rich neutrino-driven winds

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Nucleosynthesis of elements between Sr and Ag in neutron- and proton-rich neutrino-driven winds

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