1. Bar-driven Evolution and Instability of Self-gravitating Disks
Chi Yuan
Institute of Astronomy and Astrophysics
Academia Sinica, Taipei, Taiwan, ROC
David C.C. Yen, Yi-Hsin Liu, Chao-Chin Yang

2. Three Observational Facts
Starburst rings
Dense circumnuclear molecular disks
Gas depression central regions

3. Starburst Rings
NGC4313
NGC1512
NGC6782

4. Circumnuclear Disk in ngc1068

5. Center of M51

6. The 3-kpc Arm

7. Gas Distribution in the Milky Way

8. CO and HCN in the Milky Way

9. Distribution of Gas in Galactic Disks

10. Diamond-shaped Ring in NGC6782

11. NGC 1068 Type : Sb / AGN Distance : 14.4 Mpc ( H0 = 75 km s-1 Mpc-1 )
1 arcsec = 74 pc
9.5 arcmin

12. The Antares Code 大火程序 A high-performance CFD-MHD code for astrophysics
It is a second-order Godunov code (or codes) equipped with exact Riemann solver and the balance law correction. (2-D)
It is also featured with the fft Poisson solver, to include the self-gravitation of the disk, and with characteristics decomposition on the boundary, to guarantee the true radiation (non-reflecting) boundary conditions.

13. Governing Equations

14. Schematic Picture of a Bar
In Numerical Simulations

15. Nearly Flat Rotation Curve
OILR
OLR

16. Cases of Double Resonances: OLR-OILR

17. Double Ring Feature

18. Elmegreen Rotation Curve

19. Cases for a Single OLR

20. Evolution of Self-gravitating Disks

21. Double Rings and Central Spirals

22. Double Rings and Central Spirals

23. Q-value for Self-gravitating Disk

24. Onset of Instability

25. Disk Instability

26. A fast nuclear bar like possibly NGC4313 (OLR).
Conclusions
Starburst rings are the results of a gaseous disk responding to a rotating bar potential. But, there are many possibilities.
A fast nuclear bar like NGC1068 or the Milky Way (OLR and OILR)
A fast nuclear bar like possibly NGC4313 (OLR).

27. Conclusions cont. A double ring due slow bar like NGC6278 (OLR-OILR).
A fast bar in the center solves the starburst ring, dense circumnuclear molecular disk, and depletion of gas in between all together.
Self-gravitation plays an important role. It leads to instability, chaos, and star formation
Toomre’s criterion Q=1 works extremely well.