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