Post on 13-Jan-2016
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
Augusto Damineli (IAGUSP)
Robert Blum (NOAO)
Peter Conti (JILA)
Elysandra Figuerêdo (Open Un.)
Alessandro Moisés (IAGUSP)
The Stellar Content of Galactic Giant HII Regions
MellingerMellinger2MASS2MASS
Many methods indicate Sb-Sc types
Where are trhe arms? Longer wavelengths => clear view, but mixed structures
RVs of radio recombination lines from HII regions => Distances to HII regions + rotation curve
face-on map
(l,b) coordinates
Clemens 1985
SunHII RegionsRusseil 2003
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
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
Our Method: Giant HII Regions (NLyc=>1050 ph/s =>10 O7V*) good tracers of the spiral arms
selected from radio and FIR surveys
50 imaged with Blanco/SOAR
Colour- Magnitude Diagram:
foreground stars
ZAMS of the HIIR
Candidates for spectroscopy
Spectroscopy of O-type stars:
Distance Module
DSpPtHanson, Conti & Rieke (1996)
Spectral Type
O6V O8V
Late O-type stars
lines used to determine the spectral type
Id Kdist
kpcref Sppdist
kpcref
M8 2.8 R03 0.6 Bik04
W31 >4.1-12.3 C&E04 3.4 ± 0.5 BDC
M17 2.4 R03 1.3 Hans97
W42 3.7 -11.5 R03 2.2 ±0.8 BCD
W43 6.2 R03 5.9 ± 0.7 BDC
W49A 11.8 Wetal04 8.4 Bik04
W51A 5.5 R03 2.2 F07
W3OH 4.2 R03 1.95 Xu06
NGC3603* 7.9 R03 6.0 Stolte04
G282.0-1.2G298.9-0.4
5.910.4 R03
5.3 ±1.23
F05Bik04
G333.1-0.4G331.5–0.1
3.510.8
R03R03
2.4 ±0.44.5 ±0.3
F05F05
All shifts are toward smaller distances!
Conti & Crowther 2004
Sun
GC
Star Formation Rate in the Milky Way
Scaling the reduction to all sources
NLyC = 1.7 × 1052 ≥ 1.8 M/year
Conti & Crowther 2004NLyC = 2.4 × 1052 ≥ 2.6
M/year
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
What is the role of the reddening law?
AK ~ 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:
G353.19+0.64
Ak=1
Ak=2
Ak=3
Name DK DNish DMat 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
--- 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
SalpeterIn line with Massey 2003
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)