1. Dynamically distinct zones of disk of M51: diagnostics with HST/WFC photometry

2. What shall we do today critical review on the diagrams
find CAVEATS
find extra data / curves to be plotted
find extra figures to be produced
how to revise format
Outline the section of discussion
Polish up the title (^^;

3. Color-mag. diagmram

4. CMD of SFR / interarm region

5. left: O(dark blue) + B(light blue)
right: RSG (green) + RGB (red)
solid curves: logarithmic spiral (eyeball fit)

6. RSGs with HII regions

7. RGB/RSG stars on K-band

8. RGB/RSG on K (zoomed up)

9. Counts of red stars (V-I > 0.8)
RSG dominates in luminosity in the SFRs
regions 1-5 as specified above

10. Blue(OB), RSG(green), black (HII region), CO(red grayscale)

11. Is the measurement reliable enough ?
Independent measurement is welcome
rcorot depends on the identification at r = 6 kpc
Objective profile-peak detection / cross-correlation more or less requires eye-inspection. Profile/CC are powerful if profile have a good S/N.
By providing ranges of azimuth with higher density, peak positions are conservatively shown with ambiguities, which would not alter our conclusion seriously, a posteriori.

12. peak definition for star/CO profiles

13. Ω-θ plot for arm 1(red) /2(blue)
peak positions (bar); dots simply indicate midpoint of the bars

14. Ω-θ diagram with choices of axes which one do you favor ?

15. Main results: Ωp(r) two distinct zones: boundary: 3.5kpc
inner: variable Ωp
mid-disk: constant
boundary: 3.5kpc
m=3 resonance ?
stars follows the rotation
caveat: tOB
consistency with Ωp at 6kpc
need to be careful to identify SF sites from HII regions
thick curve: Rotation curve
thin curve: m=3 (Ω±κ/3)
dashed curve: m=2 (Ω±κ/2)

16. How about the outerdisk? (r > 6kpc)
seems that OB stars precede HII regions: is Ωp even slower? OB and HII shows small displacement in the bridge between M51 and N5195 (arm 1); is this part a material arm ?

17. Topics for discussion: Ωp(r)
three distinct zones:
inner: decreasing Ωp ( boundary: m = 3 resonance )
mid-disk: constant ( boundary: corotation )
outerdisk: decreasing Ωp (?)
How did this situation come to be ?
i.e. in which situation a constant Ωp is realized ?
i.e. what determines Ωp after all ?

18. Bright (short-lived) “O” stars with shorter tOB

19. Vp = Ωp ×r ! Thick curve: rotation curve

20. d = Vp ×tOB !

21. background keywords for discussion ?
swing amplification ?

22. Related papers for discussion ?
Egusa ApJ 697, 1870
Assumed constant Ωp
Foyle+ (2011) ApJ 735, 101
No systematic offset are found among any tracers
Louie+ (2013) ApJ
CO/Hα: the best among the tracers
Shetty+ (2007) ApJ 665, 1138
Fabry-Perot Hα velocity map of 25km/s)
Zimmer+ (2004) ApJ 607, 285
TW method, Ωp=40 kms/s/kpc (applied 3 galaxies)
Meidt+ (2008) ApJ 688, 224
TW method: decreasing Ωp
Henry+ (2003) AJ 126, 2831
M=3 arm

23. Related papers for discussion ?
Dobbs+ (2010) MNRAS 403, 625
No single global Ωp: Simulation of M51/N5195
Wada et al. (2008,2011)
Grand+ (2012) MNRAS 421, 1529
Simulation favors decreasing Ωp
Sellwood ?
Minchev+ (2012) AA 548, 124
Comprehensive study on the model disk
D’Onghia+ (2013) ApJ 766, 34
Self-induced spiral arm survive due to strong non-linear effects
Guiterrez+ (2011) AJ 141, 113
Catalog of HII regions (HST/ACS)
Koda+ ApJ 700 L132
GMC: are some topics important for us?

24. detection & completeness
would be revised…

25. Discriminating shape
χ２ ～ 1, sharpness～0 for stars Objects are mostly stars for our case only if they are not fake