Stellar evolution and population synthesis. evolutionary tracks, metallicity vs. age. Origin of elements and yields. Supernovae and hypernovae

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1 Chap.2 Stellar populations and chemical evolution Stars in a color-manitude diaram nearby stars, lobular clusters Stellar evolution and population synthesis evolutionary tracks, metallicity vs. ae star ormation, sinle starburst model Oriin o elements and yields Supernovae and hypernovae Extremely metal-poor stars Neutron capture elements, CEMP stars Chemical evolution IMF, SF, Simple model, G-dwar problem 2. Stars in a color-manitude diaram CM diaram or nearby stars Hertzsprun ap ed-giant Branch elative error in parallax < 0% ed Clump Subiant Branch Many youn stars + some old stars 2 CM diaram or a Galactic lobular cluster M68 [Fe/H]= -.99 Horizontal Branch m v Gyr Turn O 3 Gyr CM diarams or Galactic lobular clusters M3 [Fe/H]= Tuc [Fe/H]= Asymptotic Giant Branch Horizontal Branch 3 4

2 Evolutionary tracks Iben 967, AAA, 5, Stellar evolution and population synthesis M 0.08 Msun : nuclear reaction 2 Msun : helium lash (T c ~0 8 K Evolutionary track or low to hih mass stars (Iben 985, QJAS, 26, Evolutionary track or low mass 6 5 M3 [Fe/H]= Tuc [Fe/H]= m V Salaris et al 997, ApJ, 479, M5 [Fe/H]=

3 Worthey 994, ApJS, 95, 07 Ae-metallicity deeneracy 9 HB morpholoy Mc=0.477M sun He-core mass edder or more metal-rich stars Number:= total mass (incl.h envelope Mc=0.498M sun Lee et al. 990, ApJ, 350, 55 Sweiart 987, ApJS, 65, 95 HB ~ 0. Gyr 0 HB type (color vs. metallicity in Galactic lobular clusters dispersion Ferraro et al multiple stellar population M=5 x 0 6 Msun Most massive lobular cluster More red BHBs or hiher [Fe/H] What is the oriin? 2

4 Worthey 994, ApJS, 95, 07 Population synthesis Ae-metallicity deeneracy Oriin o elements and yields M<8M sun (Type Ia SNe white dwar, mass accretion rom a companion Iron peak elements (Cr, Mn, Fe, Co, Ni M>8M sun (Type II SNe Core-collapse supernovae -elements ( 6 O, 20 Ne, 24 M, 28 Si, 32 S, 36 Ar, 40 Ca, 44 Ti hydrostatic burnin 8<M<0M sun C-burninO+Ne+M-coreAGB star O+Ne+M WD ater losin H-He envelope or collapse due to e - capture 0<M<40M sun Fe-coreravitational collapseneutron star or black hole 40<M<300M sun Pair-Instability SNe Electron-positron pair creation & core collapsehih T c & explosive O burnindisrupt out completely due to explosion, release a lot o Fe & Ca M > 300M sun Photo-disinterationcore collapse, BH ormation Hypernovae (M>20M sun, E>0 52 er amma-ray burst Lare [n/fe] & [Co/Fe] ratios 4 Supernova and Hypernova Yields (Nomoto et al Elements rom Type II SN 6 O, 20 Ne, 24 M, 28 Si, 32 S, 36 Ar, 40 Ca Created at C- & O-burnin phase 2 C Ne+ 4 He, 20 Ne O Si+ 4 He, Mass Number Elements rom Type Ia SN 5 Tsujimoto et al. 995, MN, 277, 945 Iron peak nuclides Cr,Mn,Fe,Co,Ni 6

5 Solar System Abundances r-process s-process Mass Number 7 Oriin o elements heavier than Fe ~ neutron capture process ~ 34 Ba 35 Ba 36 Ba 33 Cs 34 Cs 3 Xe 32 Xe 33 Xe Neutron number 8 Atomic Number Solar System Abundances Ater neutron capture, atomic number is increased throuh beta decay Neutron capture decay decay r-process ( < ( decay Eu, Pt, Au, Th, U core-collapse SNe or merin o neutron stars s-process ( > ( decay Ba, Pb AGB stars Families o elements Liht odd- elements (Na and Al: Mainly made in the hydrostatic burnin shells o massive stars. Their yields are related to the mass o the shell, which is related to the initial mass o the star 2 Manesium: Made in the hydrostatic burnin shells o massive stars (speciically the C-burnin shell, and the yield is related to the initial mass o the star. 3 The other alpha elements (O, Si, Ca, and Ti: O is ormed in a hydrostatic burnin shell (the He-burnin shell. The heavier alpha-elements Si, Ca and Ti are ormed deep within massive stars durin the explosive burnin phase o a supernova (SN. 4 Fe-peak elements (Sc, V, Cr, Mn, Fe, Co, Ni, Cu and n: With the exception o Cu and maybe n, these elements are made in both Type Ia and Type II SNe durin the explosive phases. Co and possibly n are made almost exclusively in Type II SNe. Hypernovae is required or n. 5 Liht s-process elements (Sr, Y, and r: (Nearly all the elements heavier than n are made by neutron-capture processes. Made in metal-rich AGB stars. The peak o the s-process production moves to lihter elements as metallicity increases because there are more Fe-roup seed nuclei at hiher metallicity, 6 Heavy s-process elements (Ba and La: Made in metal-poor AGB stars, althouh some o the inventory o both elements in the Sun came orm the r-process. 7 r-process element (Eu: Provided by the explosive phase o Type II SNe or merin o neutron stars. List o elements and their production sites Lithium (=3: Produced in Bi Ban nucleosynthesis and cosmic ray spallation. Carbon (=6: esults rom the triple-alpha He-burnin process. Isotope ratios between 2 C and 3 C are aected by hydroen burnin on the CNO cycle. Oxyen (=8: esults rom hydrostatic He-burnin burnin in massive stars, yield related to the mass o the He-burnin shell, which is a unction o the star s initial mass. Sodium (=: esults mostly rom carbon-burnin. Production depends on the n/p ratio, so there is a predicted metallicity dependence o the yield rom SN II. Can also be aected by H-burnin in intermediate-mass stars, as seen in the so-called Na-O anti-correlation oten seen in lobular cluster stars. Manesium (=2: esults rom carbon-burnin. Eectively 2 C 24 M via 20 Ne + 4 He. eleased rom SN II. Aluminum (=3: Carbon-burnin; closely tied to the production o the minor M isotopes 25,26 M. Production depends on the n/p ratio, so there is a predicted metallicity dependence o the yield rom SN II. Can also be aected by H-burnin in intermediate-mass stars, as seen in Na-O anti-correlation in lobular cluster stars. Silicon (=4: Explosive oxyen burnin via 2OSi + He, with M + HeSi. SN II+SN Ia. Calcium (=20: Oxyen and silicon burnin, both hydrostatic and explosive. SN II. Scandium (=2: SN II rom oxyen burnin + the alpha-rich reezeout. Titanium (=22: Explosive Si burnin, + alpha-rich reezeout, includin white dwars (SN Ia. Appears to be mostly SN II.

6 Vanadium (=23: Explosive oxyen burnin + silicon burnin. SN Ia probably dominate production. The [V/Fe] value is very sensitive to the value o Te. Chromium (=24: Equilibrium process in explosive Si burnin. SN II + SN Ia, but dominated by SN II. Mananese (=25: Explosive Si burnin + alpha-rich reezeout. SN II. Metallicity dep. Iron (=26: Equilibrium process. SN II + SN Ia, with a lare yield rom SN Ia. Cobalt (=27: Explosive Si burnin + alpha-rich reezeout (which produces a lare Co/Fe yield. Possibly metallicity-dependent yields in Type II SN. Nickel (=28:. Explosive Si burnin + alpha-rich reezeout. SN II + SN Ia Copper (=29: Possibly rom SN II only with metallicity-dependent yields. Minor contributions rom the s-process and SN Ia. inc (=30: Explosive Si burnin + alpha-rich reezeout + s-process. n does not orm on dust rains, so it is used in the study o damped Lyman-alpha systems as metallicity indicator. Strontium (=38, Yttrium (=39, irconium (=40, Molybdenum (=42, and Palladium (=46: Liht s-process. AGB stars and maybe massive stars ( weak s-process. Barium (=56: Heavy s-process. AGB stars. [heavy s/liht s]= (. Lanthanum (=57: Heavy s-process. AGB stars. [heavy s/liht s]= (. Europium (=63: Bypassed by s-process (mostly, best r-process only element in the optical. The r-processes is believed to occur in a sub-class o SN II, most likely the lower-mass SN II. Where elements came rom Extremely metal-poor stars -2.5 These stars were enriched by just one supernova. Their abundance patterns relect the mass o a proenitor star (irst star. 23 -elements 24

7 r-process elements or a star with [Fe/H]=-3. s-process elements or a star with [Fe/H]=-2.7 Atomic Number Carbon-enhanced extremely metal-poor star (CEMP Universal mechanism (by SNe II or merin o neutron stars is at work or r-process. 25 Nucleosynthesis rom Hypernovae (Tominaa et al M=25M sun, E=0 52 er [X/Fe] (obs Mixin-allback model Observed lare [n/fe] & [Co/Fe] ratios are reproduced Chemical evolution Simple model Key parameters: SF: (t, IMF: (M star: M s, as: M, metal: M z, metallicity: =M z /M closed box: M tot = M s +M = const. instantaneous recyclin. Massive stars die immediately and leave enriched as (ae: The rate o as ejection is: m ( t ( M w ( M ( t ( M dm ( M w m ( M ( t dm M M y: yield metallicity when a unit as mass is locked into stars 27 dm dt d S ( M dt y M dt dm ln M s s s M M ( tot current y ln y ( current ( : as raction < 0 current current S(: cumulative metallicity distribution o stars simple model obs Obs: G-dwar stars near the Sun Simple model: too many metal-poor stars G-dwar problem pre-enrichment extreme inall Tinsley 980, FCPs, 5, ,,,, /

8 Gaseous Oxyen abundance in M8 Garnett & Shields 987, ApJ, 37, 82 Gaseous Oxyen in various alaxies Simple model Gas raction (HI 29 Gas raction (HI SF law or 6 disk alaxies and 36 starburst alaxies Kennicutt 998, ApJ, 498, 54 lo SF N SF as N=.4 lo as 30 Initial Mass Function (m m - (m(mdm=m sun Kroupa (2002 Salpeter (955 = 2.35 or M sun < m Miller and Scalo (979, Scalo (986 0 or m < M sun Kroupa (2002 = 0.3 or m < 0.08M sun.3 or 0.08 < m < 0.5M sun 2.3 or 0.5M sun < m 3 G-dwars in the solar neihborhood (model: Sommer-Larsen & Yoshii 990, MN, 243, 468 as /dtexp(-t / t inall t inall ~4-5 Gyr is required t inall =4.6Gyr no inall The Galactic disk ormed slowly over 4-5 Gyr. bule as low Galactic disk The 32 Sun & nearby stars

9 Chemical clock Yoshii et al. 996, ApJ, 426, 266 break [Fe/H] Time scale or Type Ia SN : ~ Gyr (at [Fe/H] ~ - near the Sun 33 adial miration o stars Sellwood & Binney 2002, Schoenrich & Binney 2009 transient spiral arms V V V 34 adial miration o stars Minchev+ 203: simulation studies 7 < < 9kpc r 0 7 < < 9kpc r 0 35 Johnson et al