1. The Chemical and Color Evolution of M33 2008.12 Reporter: Jun Yin (Shao) Supervisor: Jinliang Hou (Shao)

2. Contents Observations 1 Models 2 Results & Forming History 3 Summary 4

3. 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

4. Observation • H2,tot=0.2×109M⊙, HItot=2.2×109M⊙ • rd,H2=2.5kpc, rd,tot=7.8kpc whole gas & SFR abundance SB, color

5. Observation whole gas & SFR abundance SB, color

6. Observation whole gas & SFR abundance SB, color MFUV = -16.63 (GALEX) MK = -21.78 (2MASS) Munoz-Mateos et al. (2007)

7. Chemical & Color Evolution Model Initial conditions stellar evolution theory Star Formation Rate mass SFR Gas Infall Rate Z, MDF Outflow…… color ……

8. 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

9. 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

10. 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

11. 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

12. Results & Forming History • MDF & evolution of some global variables in our best model • τ= r+5 Gyr • td = 0 Gyr • b= 1.0

13. 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.

14. Thank You !