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The Chemical and Color Evolution of M33. 2008.12. Reporter: Jun Yin (Shao) Supervisor: Jinliang Hou (Shao). Contents. Observations. 1. Models. 2. Results & Forming History. 3. Summary. 4. Observation. Sc II-III, i=56, D=840 kpc M tot =5~8×10 9 M ⊙
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The Chemical and Color Evolution of M33 2008.12 Reporter: Jun Yin (Shao) Supervisor: Jinliang Hou (Shao)
Contents Observations 1 Models 2 Results & Forming History 3 Summary 4
Observation • Sc II-III, i=56, D=840 kpc • Mtot=5~8×109M⊙ • rd,tot=2.4kpc, rd,*~1.4kpc • no merger whole gas & SFR abundance SB, color
Observation • H2,tot=0.2×109M⊙, HItot=2.2×109M⊙ • rd,H2=2.5kpc, rd,tot=7.8kpc whole gas & SFR abundance SB, color
Observation whole gas & SFR abundance SB, color
Observation whole gas & SFR abundance SB, color MFUV = -16.63 (GALEX) MK = -21.78 (2MASS) Munoz-Mateos et al. (2007)
Chemical & Color Evolution Model Initial conditions stellar evolution theory Star Formation Rate mass SFR Gas Infall Rate Z, MDF Outflow…… color ……
Model • fout~b·Ψ, Zout=Z(t) • Mtot=7×109M⊙, rd,tot=2.2kpc Σtot(r)=230*exp(-r/rd,tot) Total SFR • Ψ~(Σgas)1.4 r -1 • fin~t·exp(-t/τ), Zin=0 • td=a·r Gyr Infall rate Outflow
Results & Forming History • Does M33 form quickly ? • if τsmall infall quick gas,SFR low stellar disk big abundance high, steep SB dark, color red NO τ= r+5 Gyr
Results & Forming History • Does infall delay at outer part ? • if td large infall late gasfraction high stellar disk small abundance low, steep color blue, steep μr= 23.2 mag arcsec-2 Gkpc= -0.016 Not necessary -0.015 -0.022 -0.034 td = 0 Gyr
Results & Forming History • Does gas flow out ? • if b large outflow large gas, SFR, star do not change much abundance low, flat color a little flatter μr= 23.2 mag arcsec-2 Gkpc= -0.016 YES ! -0.020 -0.017 -0.015 b=1.0
Results & Forming History • MDF & evolution of some global variables in our best model • τ= r+5 Gyr • td = 0 Gyr • b= 1.0
Summary • M33 should be forming though slow accretion process, i.e. longer infall time scale. • The whole disk should form simutaneously, no obvious infall delay at outer disk. • Outflow is not negligiblebecause of its low metallicity. • The M33 should obey similar SF law with our Galaxy.