1. Probing Galactic Central Region of Normal Galaxies with Photometric Method August, 27, 2002 Student Yeong-jyi Lei Advisor Chi Yuan Chien-Chang Yen

2. Outline Introduction of Hubble sequence Our candidates Photometric method :Wavelet method Observation results Compare our result with other photometrical method Conclusion

3. Hubble Tuning-fork Diagram

4. Typical Early-Type galaxies IC 4296(E0) NGC 4365(E3) NGC4564(E6) NGC 4623(E7)NGC 4251(S0)NGC 4340(SB0)

5. Typical normal Spirals NGC4736(Sb) NGC3898(Sa) NGC4321(Sc)NGC4594(Sa/Sb)

6. Typical Barred Spirals NGC 175 (SBab)NGC 1300 (SBb) NGC 2525(SBc)

7. candidates Our candidates are from the list of 183 disk galaxies, they are proposed by Luis Ho. We choose the well-observed data, which have two properties: they are almost face-on and their origins are nearly in the center of images. (33 normal galaxies)

8. Introduction to wavelet method ++ = Wavelet Wavelet method provides us a multi-scale analysis. It decomposes data at some certain scale into different planes Wj, j=0,1,2,3,4,5,…. When we say wavelet planes 1 to 4, meaning W1+W2+W3+W4. The following is a numerical example:

9. NGC1667(Sc)

11. NGC4321(Sc)

13. NGC5055(Sbc)

15. NGC5005(Sb)

17. NGC5806(Sb)

19. NGC4698(Sa)

21. NGC4459(S0)

23. NGC3412(S0)

25. Clear spiralNot clearNo spiral S016 Sa15 Sab1 Sb24 Sbc231 Sc52

26. Compare our result with other photometrical method (NGC7743 SBa)

27. Conclusion There is usually no spiral structure in the central region for Sa(S0) type and clear spiral structure for Sc type. The evolution of normal galactic from Sc to Sa can be suggested by our observation.