2 nd Mar 2011 恒星進化 星形成から探る銀河の形成 進化の研究宇宙最初の星から太陽系形成まで
Fe Si NS/BH Massive Star (>10M ) e - -capture SNe (8-10M ) O C He H SN Ic SN Ib SN II Temp [10 8 K] 0.2 1.5 7 15 30 40 50 Burning Stage H He C Ne O Si NSE Products He C,O Ne,Mg O,Mg Si Cr,Mn 56 Ni Core collapse driven by Fe photodisociation NS/BH formation Energy deposition
Abundances Post-shock Temperature T R -3/4 E 1/4 Shock propagation Presupernova structure 4 He 54 Fe56 Ni 28 16 Si O fallback 4 He 20 Ne Mr[M ] 12 C 24 Mg 28 Si Temperature [10 9 K] 5 4 3 Heavier elements higher-t & inner layers Complete Si burning Fe,α,Ni,Zn,Co,V Incomplete Si burning Fe,Si,Cr,Mn O burning Si
(e.g., Cayrel + 04; Honda + 04) 元素組成が不均一 r-process process [Fe/H]<-5 Hyper Metal-Poor (HMP) [Fe/H]<-4 Ultra Metal-Poor (UMP) [Fe/H]<-3 Extremely Metal-Poor (EMP) [Fe/H]<-2 Very Metal-poor (VMP) (Beers & Christlieb 05) HMP UMP EMP CEMP VMP A few SNe contributed to the EMP stars(e.g., Tumlinson 06)
H, He Fe, C, O, Mg, Si, Ca SN-induced Star Formation (e.g., Cioffi et al. 1988; Shigeyama & Tsujimoto 1998) The next-generation star is made from the mixture of the matter ejected by the SN (Fe, C, O, etc.) and swept-up by the shockwave (H, He). If ISM is metal-poor (Z<10-3 Z ), all metals in the next-generation stars are synthesized and ejected by the parent SN. [A/H]~log(M ej (A)/M sw (H))+con. [A/B]~log(M ej (A)/M ej (B))+con.
H, He 星形成 超新星爆発 重元素汚染 H, He, Z
M(Fe)/2 M(Fe)x2 Timmes+95
Normal SN model (25M, E 51 =1) 金属欠乏星 (Cayrel+04) SN model (NT+07b) 1 C O Ne Mg Si S Ar Ca Ti Cr Fe Ni Zn Hypernova model (25M, E 51 =10) [X/Fe] 0-1 B N F Na Al P Cl K Sc V Mn Co Cu Ga NT+07b 5 10 15 20 25 30 Z
Mixing-fallback model Umeda & Nomoto 2002 M mix (out) f M cut (ini) H.Umeda
1 C O Ne Mg Si S Ar Ca Ti Cr Fe Ni Zn Hypernova model with mixing and fallback [X/Fe] 0-1 B N F Na Al P Cl K Sc V Mn Co Cu Ga 5 10 15 20 25 30 NT+07b Z Kobayashi,,NT+06
すばる望遠鏡
Umeda & Nomoto 03,05; Iwamoto,,NT,+05
~ Mixing region Si 層まで Ejection factor f~0.1 EMP ~ ONeMg 層まで f~10-3 CEMP ~ C+O 層まで f~10-5 HMP
Rayleigh-Taylor 不安定 + Fallback (e.g., SN1987A) ジェット状爆発 (e.g., GRB-HNe) NT+07b weak explosion E<10 51 erg に限る
Mixing mechanism Rayleigh-Taylor 不安定 + Fallback ジェット状爆発 Fe O Joggerst+10 NT+07a
Rayleigh-Taylor 不安定 + Fallback Low [(Co.Zn)/Fe] ジェット状爆発 Not-high [C/Fe,Mg] Joggerst+10 NT+07a
Metal-poor stars tend to have high [C/Fe] for low [Fe/H]. Hyper metal poor (HMP) 4 [C/Fe] 3 2 Ultra metal poor (UMP) C enhanced EMP (CEMP) 1. Faint SN 2. 2 種類の SNe (Fe 無 + normal SN) 3. AGB 伴星からの質量降着 4. 回転する大質量星からの質量放出 1 Extremely metalpoor 0 (EMP) -1-5 -4-3 [Fe/H]
C N O (Suda+04; Nishimura+09)
C-rich DLA ([Fe/H]~-3) HE 0143 0441 ([Fe/H] = 2.21, Cohen + 04) BD+44 493 ([Fe/H] = 3.73, Ito + 09)
C-rich DLA ([Fe/H]~-3, z=2.3) peculiar DLA ([Fe/H]~-1.5, z=1.6, Cooke+10) Kobayashi, NT + 11 ApJL in press (arxiv:1101.1227)
HK survey: ~10,000 MP candidates Hamburg/ESO survey: ~10,000 MP candidates SDSS/SEGUE: ~100,000 candidates 2007: SEGUE (Sloan Digital Sky Survey) 2009: Skymapper (ANU) 2011: APOGEE (SDSS: R~20,000, 10 6 stars) 201?: HERMES (AAT: R~28,000, 10 6 stars) 201?: SuMIRe-PFS (IPMU/SUBARU: R~4,000, 10 6 stars)
Caveat O+Mg [Mg/Si]~1.4 Jet Fe Si He O+Mg Fe Si Abundance mixing due to the ISM interaction?? H NT09 Nakasato & Shigeyama 2000 R/10 14 [cm]