Evolutions of stars just below the critical mass for iron core - PowerPoint PPT Presentation

Evolutions of stars just below the critical mass for iron core formation Koh Takahashi, Hideyuki Umeda, & Takashi Yoshida Department of Astronomy, University of Tokyo 9-11Moの恒星のコア進化

Introduction 9-11Mo stars evolution ・Fe core formation → CCSNe M crit =?? ・complex features ・Thermal Pulse (SAGB) ・ONeMg core ?? → ECSNe

Introduction 9-11Mo stars evolution ・calculate with large nuclear reaction network (282 species of nuclei : from n, H to Br) and with fine initial mass grid (ΔM = 0.01Mo) 1 1 79 ・Poelarends et al. (2008) ・Nomoto & Hashimoto (1988)

center T-rho diagram T C ~10^4 yr Fe core Ne+O+Si C H T He ~10^6 yr He T H ~10^7 yr M crit ? → CCSNe ・ECSNe ? →・ONeMg WDs? O+Ne+Mg core 10 9.5 9 log T c [K] 8.5 8 7.5 M=9 M o M=10 M o 7 0 2 4 6 8 10 log ! c [g/cc]

H center T-rho diagram He Mg 9Mo(beginning of TP) : ONeMg core Ne+O+Si C He T He ~10^6 yr T C ~10^4 yr T H ~10^7 yr → CCSNe ・ECSNe ? →・ONeMg WDs? O+Ne+Mg core Fe core H M crit ? 10 1 9.5 O Ne 0.1 9 log T c [K] 0.01 mass fraction 8.5 0.001 8 H He 0.0001 C 7.5 O Ne Mg Si M=9 M o Fe M=10 M o 1e-05 7 0 0.5 1 1.5 2 0 2 4 6 8 10 mass[M/M o ] log ! c [g/cc]

He T He ~10^6 yr O+Ne+Mg core →・ONeMg WDs? ・ECSNe ? → CCSNe T H ~10^7 yr T C ~10^4 yr He center T-rho diagram C Ne+O+Si 10Mo(before Core Collapse) : Fe core Fe Si O Fe core H M crit ? 10 1 9.5 0.1 9 log T c [K] 0.01 mass fraction 8.5 0.001 8 H He 0.0001 C 7.5 O Ne Mg Si M=9 M o Fe M=10 M o 1e-05 7 0 0.5 1 1.5 2 0 2 4 6 8 10 mass[M/M o ] log ! c [g/cc]

・degenerate core evolution Fe core ・for Fe core formation, Mcrit = ? M crit ? degenerate core Ne+O+Si C H He T He ~10^6 yr T C ~10^4 yr T H ~10^7 yr → CCSNe ・ECSNe ? →・ONeMg WDs? O+Ne+Mg core center T-rho diagram 10 9.5 9 log T c [K] 8.5 8 7.5 M=9 M o M=10 M o 7 0 2 4 6 8 10 log ! c [g/cc]

Results 10 9.5 9 log T c [K] 8.5 8 M/M o =9 9.5 9.7 9.8 9.78 7.5 9.79 9.9 9.81 10 11 7 0 2 4 6 8 10 log ! c [g/cc]

・ : measure point (at the end of C burning) 1.369 1.71 1.27 1.49 1.40 1.40 Results 1.370 1.38 1.33 1.29 1.373 M crit ~ 1.38 Mo(9.8 Mo) for Si burning for Fe core formation, M COcore > 1.38 Mo ・1.71 etc. : CO core mass [Mo] M crit ~ 1.37 Mo(9.7 Mo) for Ne burning M/M o =9 9.5 9.4 9.7 9.8 9.78 9.79 9.9 9.81 9.2 10 11 log T c [K] 9 8.8 8.6 8.4 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 log ! c [g/cc]

for 9.8Mo ②Ne+O+Si pulse ① property change for 9.9Mo some features M/M o =9 9.5 9.4 9.7 9.8 9.78 9.79 9.9 9.81 9.2 10 11 log T c [K] 9 8.8 8.6 8.4 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 log ! c [g/cc]

②Ne+O+Si pulse Mg Ne O Si 9.8Mo : beginning of Ne burning for 9.8Mo ① property change for 9.9Mo some features M/M o =9 9.5 9.4 9.7 1 9.8 9.78 9.79 9.9 9.81 9.2 10 0.1 11 log T c [K] 9 0.01 mass fraction 8.8 0.001 H He 0.0001 C 8.6 O Ne Mg Si Fe 1e-05 8.4 0 0.5 1 1.5 2 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 mass[M/M o ] log ! c [g/cc]

②Ne+O+Si pulse Mg Ne O Si 9.8Mo : Ne burning termination for 9.8Mo ① property change for 9.9Mo some features M/M o =9 9.5 9.4 9.7 1 9.8 9.78 9.79 9.9 9.81 9.2 10 0.1 11 log T c [K] 9 0.01 mass fraction 8.8 0.001 H He 0.0001 C 8.6 O Ne Mg Si Fe 1e-05 8.4 0 0.5 1 1.5 2 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 mass[M/M o ] log ! c [g/cc]

・electron capture on O products ① electron capture for 9.8Mo Ye ~ 0.48 M Ch = 1.46(2Ye)^2 Mo 0.9 0.8 elec mole fraction 0.7 0.6 0.5 0.4 0 0.5 1 1.5 2 mass[M/M o ]

for 9.8Mo ②Ne+O+Si pulse ① property change for 9.9Mo some features M/M o =9 9.5 9.4 9.7 9.8 9.78 9.79 9.9 9.81 9.2 10 11 log T c [K] 9 8.8 8.6 8.4 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 log ! c [g/cc]

②Ne+O+Si pulse Mg Ne O Si 9.9Mo : Ne+O+Si burning → Fe shell for 9.8Mo ① property change for 9.9Mo some features M/M o =9 9.5 9.4 9.7 1 9.8 9.78 9.79 9.9 9.81 9.2 10 0.1 11 log T c [K] 9 0.01 mass fraction 8.8 0.001 H He 0.0001 C 8.6 O Ne Mg Si Fe 1e-05 8.4 0 0.5 1 1.5 2 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 mass [M/M o ] log ! c [g/cc]

Mg some features Ne O Si Fe 9.9Mo : Ne+O+Si burning → Fe shell for 9.8Mo ① property change ②Ne+O+Si pulse for 9.9Mo M/M o =9 9.5 9.4 9.7 1 9.8 9.78 9.79 9.9 9.81 9.2 10 0.1 11 log T c [K] 9 0.01 mass fraction 8.8 0.001 H He 0.0001 C 8.6 O Ne Mg Si Fe 1e-05 8.4 0 0.5 1 1.5 2 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 mass[M/M o ] log ! c [g/cc]

for 9.8Mo ②Ne+O+Si pulse ① property change for 9.9Mo some features M/M o =9 9.5 9.4 9.7 9.8 9.78 9.79 9.9 9.81 9.2 10 11 log T c [K] 9 8.8 8.6 8.4 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 log ! c [g/cc]

Summary ・We have calculated the evolution for 9-11Mo stars with large nuclear reaction network. ・The critical mass for Ne ignition is 1.37Mo for CO core, 9.7Mo for ZAMS. ・The critical mass for Si ignition is 1.38Mo for CO core, 9.8Mo for ZAMS. ご清聴ありがとうございました ・In an electron degenerate core, effects of neutrino cooling and elec. capture are important.