tracing galactic structure with obscured luminous stars
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Madrid March 2012. Tracing Galactic structure with obscured luminous stars. Ignacio Negueruela. Madrid March 2012. Tracing Galactic structure with obscured luminous stars. + High-mass stars in the infrared. Ignacio Negueruela. Francisco Najarro Artemio Herrero. Outline. - PowerPoint PPT PresentationTRANSCRIPT
Ignacio NegueruelaIgnacio Negueruela
MadridMadridMarch 2012March 2012Tracing Galactic Tracing Galactic
structure with structure with obscured obscured luminous starsluminous stars
Ignacio NegueruelaIgnacio Negueruela
MadridMadridMarch 2012March 2012Tracing Galactic Tracing Galactic
structure with structure with obscured obscured luminous starsluminous stars
+ High-mass + High-mass stars in the stars in the infraredinfrared
Francisco NajarroFrancisco Najarro
Artemio HerreroArtemio Herrero
Outline
Piercing the dustThe obscuration problem
Obscured clustersVery massive clustersObscured populations
Galactic structureHigh-mass stars (preferably clusters) as tracers of
structure
Sagitarius
Crux
Cygnus
Orion
Perseus
Scutum
Carina
Norma
NGC 3603
QuintupletArches
Cyg OB2
Westerlund 1
Tr14+16
RSG2 RSG1
RSGC3Alicante 7, 10
Center
Westerlund 2
Alicante 8
Distribution of massive clusters in the Milky Way
Accessible from La Palma
Masgomas-1
Sagitarius
Crux
Cygnus
Orion
Perseus
Scutum
Carina
Norma
NGC 3603
QuintupletArches
Cyg OB2
Westerlund 1
Tr14+16
RSG2 RSG1
RSGC3Alicante 7
Center
Westerlund 2
Alicante 8
Distribution of massive clusters in the Milky Way
Accessible from La Palma
Masgomas-1
Accessible from Paranal
Sagitarius
Crux
Cygnus
Orion
Perseus
Scutum
Carina
Norma
NGC 3603
QuintupletArches
Cyg OB2
Westerlund 1
Tr14+16
RSG2 RSG1
RSGC3Alicante 7
Center
Westerlund 2
Alicante 8
Distribution of massive clusters in the Milky Way
Masgomas-1
Accessible in the optical
The Milky Way is hidden
Most of the Milky Way is too obscured to allow optical spectroscopy.
Study of Cl 1813-178 with Keck + NIRSPEC (Messineo et al. 2011, ApJ 733, A41)
The Milky Way is hidden Most of the Milky Way is too obscured to allow optical spectroscopy. Extinction is complex and poorly known. OB stars are needed to determine it. Combined optical+near-IR spectrophotometry.
Study of Cl 1813-178 with Keck + NIRSPEC (Messineo et al. 2011, ApJ 733, A41)
Searching for obscured massive star clusters
Optical
Near-IR
Mid-IR
Galactic centre and beyond
Molecular Clouds and Clumps in the Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey. Roman-Duval et al. 2010, ApJ 723, 492
High-mass Stars in Obscured Regions
Black Body
AV = 30
Effects of extinction !
Importance of resolution
Metallicity Studies Why metallicity?
α-elements vs Fe ratio. Top heavy IMFs constraints to evolutionary models 2-D metallicity map of the Milky Way to provide
constraints to galactic chemical evolution models
Determinations in the IR Direct estimates LBV phase Indirect estimates WNL phase Direct estimates OIf phase
Pistol Star
Najarro et al. 2007, 9
Fe Solar
Mg 2xSolar
Si 2xSolar
α/Fe= 2 !!
Infrared diagnostics for OB SGs (Najarro et al. 2011, A&A 535, A32)
IR survey of open clusters with VLT/ISAAC by the CAB high-mass star group(>80h allocated over the last 3 years)
Sagitarius
Crux
Cygnus
Orion
Perseus
Scutum
Carina
Norma
NGC 3603
QuintupletArches
Cyg OB2
Westerlund 1
Tr14+16
RSG2 RSG1
RSGC3Alicante 7, 10
Center
Westerlund 2
Alicante 8
Distribution of massive clusters in the Milky Way
Masgomas-1
Concentration of > 26 RSGs (Davies et al. 2007,
ApJ 671, 781)
Implied mass > 5x104 M
Stephenson 2
False colour image from JHK UKIDSS frames
WHT + WYFFOS, 2009
Negueruela et al., submitted
Photometric criteria detect only luminous red stars. About 230 unique objects observed. Intruders are always bright giants in the
foreground or very late (>M4) giants. We observe ~35 RSGs with high vrad (compatible
with Ste 2) over the whole field (at distances >50’ from Stephenson 2). There are many RSGs with significantly different
vrad over the whole area.
Around ℓ = 26°
Multiplexing Stephenson 2
RSGs of all tastes
Negueruela et al., submitted
Tracers of Galactic structure
Negueruela et al., submitted
MasersHII regionsRSGs
*
Negueruela et al., submitted
Tracers of Galactic structure
AAOmega data
Much higher multiplexing (>1000 stars in 3 nights) Wider field Much better access to
cluster cores Higher resolution
(R ~ 10 000)gives accuracy of 2 km/s (internal)
Heavy reddening
Very variable obscuration
No “interesting” features
Only 80 min total exposure
Limited to
I ~ 15
Field centred on Westerlund 1
Huge luminous population>80 previously unknown SGs
Field centred on Westerlund 1
Requirements – OB stars in the IR
The hidden Milky Way:• Star formation• Very massive clusters• Galactic structure
Wide field interesting, but not fundamentalMultiplexing in the near-IR @ moderate resolution ( 10 000 - 20 000 )Capability to reach cluster cores important
MIRADAS (EMIR, LIRIS)
Requirements – Galactic structure
Survey of red supergiants towards the inner Galaxy:
• Ideally in the 850 nm range (parameters, many lines, easy access), but then limited by extinction.
• K band at 10 000 good for radial velocities, but not for abundances
• H band at 20 000 (MIRADAS, but also APOGEE)
Davies et al. (2007, ApJ 671, 781)
Requirements – Galactic structure
Survey of red supergiants towards the inner Galaxy:
• Dynamics• Galactic structure
Wide field decisive, at least 1°High throughput around 850 nmCapability to reach cluster cores important
WEAVE @ 10 000 (@ 5 000, AF2, HECATE)
Ignacio NegueruelaIgnacio Negueruela
MadridMadridMarch 2012March 2012Tracing Galactic Tracing Galactic
structure with structure with obscured obscured luminous starsluminous stars