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单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Formation and evolution of the Galactic bulge:-,Constraints from stellar abundances,S.K.Ballero,F.Matteucci,L.Origlia,R.M.Rich,Contents,Background,Aim,The chemical evolution models,The data(from stars and PNe),Model results,Summary,Background,Bulge unlike disk but similar with elliptical galaxies,Wide range of Fe/H,enhancement of,-elements,narrow age dispersion,Old,and formed in a short time scale(10M,):Woosley&Weaver(1995)+some,Constraints,SMS(40M,-20M,):extrapolate WW95,Model,Gas infall and SF stop when SN-driven galactic wind starts at:,Feedback from central black hole is negligible.,Considered models,=0.33 for M1M,(Zoccali et al.2000),Scalo(1986),=1.35(1 M/M,2),Contents,Background,Aim,The chemical evolution models,The data(from stars and PNe),Model results,Summary,The data Metallicity distribution,503 bulge giant stars from Z03(Zoccali et al.2003),From 2MASS,SOFI imager,NICMOS and optical images from WFI at ESO/MPG 2.2 tele.,Disk-decontaminated(,M,K,V-K,)color-magnitude diagram+RGB templates,M/H,Assuming a-elements in the bulge similar to the trends of GCs in the halo(Zocalli,p.c.),Metallicity distribution,Solid:Z03,Dashed:FMR06a,Dotted:MR94,MR94:High resolution spectroscopy of 12 bulge K-giants,FMR06a:New high-resolution analysis of 27 K-giants,Broadly consistent,-elements,C/Fe from NIRSPEC at KeckII from Origlia et al.(2002,2005),Origlia&Rich(2004),Rich&Origlia(2005)shows a depletion up to a factor of 3,First dredge-up and cool bottom processing in RGB.,O,Mg,Si,Ca plus Na&Al from Fulbright et al.(2006b)shows enhancement in bulge stars relative to the thick and thin disk massive stars contributed more to the bulge then disk and therefore timescale for bulge formation is short.,O/Fe from Zoccali et al.(2006)is also found to be higher in bulge stars,N/O,From PNe,May self-enriched,Not dramatic for non Type I PNe(80%of total PN),N/O from symbiotic stars are consistent with those from PNe(Luna&Costa 2005),Use the compilation of Gorny(2004):their 44 PNe+those in Cuisinier et al.(2000),Escudero&Costa(2001)and Escudero et al.(2004),103 objects,Contents,Background,Aim,The chemical evolution models,The data(from stars and PNe),Model results,Summary,SN rates,R,SN1a,(century,-1,),R,SNII,(century,-1,),t(Gyr),t(Gyr),Metallicity distribution(MD),0.33,0.95,1.35,1.35,1.7,Solid histrogram:Z03,Dashed histrogram:FMR06a,IMF More flatter,Fe/H peaks,at higher values,Z00-1 quite similar to Z00-2,MD,Insensitive to,at small x,Number of massive stars is,Insensitive to,when,is small enough,Star formation efficiency,Lower efficiency,broader and lower peak,Higher efficiency narrower and higher peak,20Gyr,1,is the best fit,Effects on peak positions,are negligible,Infall timescale,Closed box,Over-estimate metal-poor wing,Fit ok.,Deficit of both metal-poor and metal-rich wings,Effects on peak positions,are negligible,Supplementary models,Evolution of abundance ratios:O/Fe,Fe/H,O/Fe,Fiducial models fit satisfactory,Z00-2 fits best,t1Gyr is excluded,Other,-elements,Fiducial model consistent,with data at turnover point,Solar neighborhood fiducial,Model inconsistent,The slopes of O/Fe and,Mg/Fe vs.Fe/H are,Different,Fe/H,O/Fe,Mg/Fe,Si/Fe,Ca/Fe,Carbon/Iron,a lower limit,Fe/H,C/Fe,-Field stars,-Clusters,Nitrogen/Oxygen-conflicts,N/O,O/H,Favour low star formation,efficiency,long infall time,Scale,steep IMF index,Conflicts with indications,from previous figures,Red box:Our data,Grevesse&Sauval(1998),O=8.83,N=7.92,Onset of primary N gives better fit,Summary,A short formation timescale(0.1Gyr)combined with a high SF efficiency(20 Gyr,-1,)fits both the DF and abundance ratios,similar to a burst of SF,Degeneracy between infall timescale and SF efficiency for DF,but breaks for O/Fe.vs.Fe/H,Lower IMF index (0.33+0.95)fits better for the bulge data.,Predicting the different behaviour of different,/Fe,no need to invoke a second infall episode,Summary,A primary nitrogen production is required by comparing with PNe data need N,O abundance measurements from stars,New and better-quality data could improve dramatically the constraints for the evolution models.,The end,Thank you!,
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