1. I want to epress my joy for: -sharing with you guys this time in this beatiful planet -sharing the excitement unveiling the secret live of the stars -sharing the friendship with Peter who opened roads to the big scenario of massive stars

2. Augusto Damineli (IAGUSP) Robert Blum (NOAO) Peter Conti (JILA) Elysandra Figuerêdo (Open Un.) Alessandro Moisés (IAGUSP) The Stellar Content of Galactic Giant HII Regions

3. Mellinger‏ 2MASS Many methods indicate Sb-Sc types Where are trhe arms? Longer wavelengths => clear view, but mixed structures

4. RVs of radio recombination lines from HII regions => Distances to HII regions + rotation curve face-on map (l,b) coordinates Clemens 1985

5. Sun HII Regions Russeil 2003

6. Radial velocities: - degenerate toward the GC line-of-sight - 2-valued r<R  Limitations of the method: Non-rotational components: - warm gas outflows from HII regions (  10 Km/s - density-wave attractive force ( up to 10 km/s) - collisions between GMCs

7. Project started ~15 years ago by Conti, Hanson, Blum… -K-band imaging+spectra of ionizing O-type stars -Spectroscopic parallax: robust physics like in the optical window -Errors constrained by multiple stellar spectra Giant HII Regions

8. Our Method: Giant HII Regions (NLyc=>10 50 ph/s =>10 O7V*) good tracers of the spiral arms selected from radio and FIR surveys 50 imaged with Blanco/SOAR

9. Colour- Magnitude Diagram: foreground stars ZAMS of the HIIR Candidates for spectroscopy

10. Spectroscopy of O-type stars: Distance Module D SpPt Hanson, Conti & Rieke (1996) Spectral Type O6VO8V Late O-type stars lines used to determine the spectral type

11. IdK dist kpc ref Spp dist kpc ref M82.8R030.6Bik04 W31 >4.1-12.3 C&E043.4 ± 0.5BDC M172.4R031.3Hans97 W423.7 -11.5R032.2 ±0.8BCD W436.2R03 5.9 ± 0.7 BDC W49A11.8Wetal048.4Bik04 W51A5.5R032.2F07 W3OH4.2R031.95 Xu06 NGC3603 * 7.9R036.0Stolte04 G282.0-1.2 G298.9-0.4 5.9 10.4R03 5.3 ± 1.2 3 F05 Bik04 G333.1-0.4 G331.5–0.1 3.5 10.8 R03 2.4 ±0.4 4.5 ±0.3 F05

12. All shifts are toward smaller distances! Conti & Crowther 2004 Sun GC

13. Star Formation Rate in the Milky Way Scaling the reduction to all sources NLyC = 1.7 × 10 52  ≥ 1.8 M  /year Conti & Crowther 2004 NLyC = 2.4 × 10 52  ≥ 2.6 M  /year

14. Trig. VLBA OH masers d = 1.95±0.04 kpc Xu et al. 2006 SpPht distance d = 2.2 kpc (optical) Humphreys 1978 W3OH: emblematic for distance discrepancy Perseus arm is at wrong kinematic distance! Kin. distance d = 4.2 kpc (RV = -45 km/s) Russeil 2003

15. What is the role of the reddening law? A K ~ 1/  Mathis (1990)  =1.7 Nishiyama et al. (2006)  =1.99 --Calibration uncertainty: MV = ± 0.7 Vacca et al. 1996 – Unresolved blends: 2 identical stars => Distance 40% smaller – Projected stars in the cluster line-of-sight Limitations of the method:

16. G353.19+0.64

17. A k =1 A k =2 A k =3

18. Name D K D Nish D Mat kpc M8 2.8 0.9 0.8 W31 >4.1-12.3 3.9 3.3 M17 2.4 1.7 1.6 W42 3.7-11.5 2.8 2.5 W43 6.2 6.3 4.7 W49A 11.8 14.7 11.0 W51A 5.5 4.0 3.0 G298.2-0.3 10.4 4.6 3.9 G333.1-0.4 3.5 3.3 2.4 G331.5-0.1 10.8 5.5 4.5

19. --- NGC3576 The slope of the luminosity function is independent of the Galactic ambient  = 0.35  0.05 K-band Luminosity Function --- G333.1-0.4 Salpeter In line with Massey 2003

20. L (H  ) [ergs/s]= ( 1.43 ×10 -12 ) NLyC [photons/s] Conti & Crowther 2004 3GHIIR + luminous M17 W49A NGC3603 Morphologic Type of Milk Way Kennicutt (1988)