1 / 27

Bar-driven Evolution and Instability of Self-gravitating Disks

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. Three Observational Facts. Starburst rings Dense circumnuclear molecular disks

vicky
Download Presentation

Bar-driven Evolution and Instability of Self-gravitating Disks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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 theMilky Way

  9. Distribution of Gas inGalactic 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. 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.

More Related