Star Formation in the Milky Way Star Formation in the Milky Way and its Neighbors in the Mid-IRand its Neighbors in the Mid-IR

Chris Wilson

McMaster University

OutlineOutline

1) Catching massive star formation “in the act”

2) Forming massive star clusters in nearby galaxies

Theme: synergies between JWST and FIR/submm telescopes (Herschel, ALMA)

SED of a massive young stellar objectSED of a massive young stellar object

Figure from Beuther et al. 2010, A&A

JWST Herschel

ALMA

Integrated SEDs of Integrated SEDs of galaxiesgalaxies

Figure from Galliano 2004, PhD thesis

HerschelJWST

ALMA

The advantage of angular resolution:The advantage of angular resolution:M81 near the dust emission peakM81 near the dust emission peak

Spitzer MIPS 160 um Herschel PACS 160 um (Gordon et al. 2004) (Bendo et al. submitted)

Searching for buried protostars:Searching for buried protostars:Not all “Starless cores” are starlessNot all “Starless cores” are starless

• Spitzer 24 um observations of L1521f from c2d survey reveal a protostar in an evolved “starless” core

Bourke et al. 2006, ApJ

Catching the start of high-mass star formationCatching the start of high-mass star formation

• Infrared dark cloud with an IRAS protostar

• 24-500 um reveals new protostar plus apparently starless cores

Beuther et al., 2010, A&A

Many candidates from Herschel surveysMany candidates from Herschel surveys

• HOBYS project mapping massive GMCs within 2 kpc (Motte et al. 2010, A&A)

• Example: NGC 7538 imaging reveals cores and filaments (Reid et al., in prep.)

20’

Sites of Massive Star Formation in the LMCSites of Massive Star Formation in the LMC

Indebetouwet al. 2008,AJ

Spitzer:R/G/B=24, 8,4.5 um

SEDs and luminosity functionSEDs and luminosity function

• Lots of molecular gas but little evidence of star formation before Spitzer observations

• Sensitive to protostars > 3 Mo

Indebetouw et al. 2008

Lo

N

Massive Young Stellar Objects in the LMCMassive Young Stellar Objects in the LMC

• Spitzer SAGE discovered 1800 massive YSO candidates (Whitney et al. 2008, Gruendl & Chu 2009)

• First Herschel strip reveals 207 embedded candidate YSOs (40% previously unknown)

Sewio et al. 2010 A&A

The youngest massive protostars in the LMCThe youngest massive protostars in the LMC

• SAGE survey missed youngest embedded sources since only went to 24 um

• Spectroscopic confirmation of YSOs through ice absorption (or maybe Silicate or PAH emission) – 300 YSOs

confirmed with Spitzer (i.e. van Loon et al. 2010, AJ)Sewio et al. 2010

Mid-IR Imaging and Spectroscopy with JWSTMid-IR Imaging and Spectroscopy with JWST

• Spectroscopic confirmation of lower luminosity YSOs• 24 microns: 1” = 0.25 pc

– Can isolate individual stars/binaries– May be able to identify dense compact young clusters

• Imaging should detect protostars below 1 Mo• What are the effects of metallicity on the formation of

individual stars?

Physical conditions in the ionized gasPhysical conditions in the ionized gas

R/G/B =8 um, B band,X-ray

Indebetouw et al. 2009, ApJ

Spectrum of entire 30 Doradus nebulaSpectrum of entire 30 Doradus nebula

Indebetouw et al. 2009, ApJ ~4’x4’ region

Note risingMIR continuum

Mid-IR spectroscopy inside an HII regionMid-IR spectroscopy inside an HII region< Brightest source< low excitation region< CO emission peak

< Prominent MIR source outside main bubble

< R136 cluster< Diffuse region, harder

radiation field< Known WN6 star R145

Indebetouw et al. 2009

Star cluster formation in M51Star cluster formation in M51

Mentuch et al., in prep., Herschel VNGS image

Calzetti et al. 2007, Spitzer SINGS image

Individual regions in M51Individual regions in M51

24 um 70 um

Spitzer SINGS image,Calzetti et al. 2007

Herschel VNGS image,Mentuch et al., in prep.

Individual regions in M51Individual regions in M51

24 um 70 um

Spitzer SINGS image,Calzetti et al. 2007

Herschel VNGS image,Mentuch et al., in prep.

Antennae: the closest Antennae: the closest major mergermajor merger

• Wilson et al. 2000, ApJ

• Whitmore et al. 1999, AJ

CO overlaid onHST optical image

The Antennae in cool dust emissionThe Antennae in cool dust emission

• Two infrared bright regions in overlap region with different 6cm/FIR indicating different ISM properties

• Herschel PACS data: Klaas et al. 2010, A&A

The Antennae in cool dust emissionThe Antennae in cool dust emission

• Two infrared bright regions in overlap region with different 6cm/FIR indicating different ISM properties

• Herschel PACS data: Klaas et al. 2010, A&A

Complex mid-IR spectra Complex mid-IR spectra in the Antennaein the Antennae

• Wilson et al. 2000, ApJ

NeIII

NeIIPAH

risingcontinuum

ISO 15 umimage

ISO CVF spectra

Complex mid-IR spectra Complex mid-IR spectra in the Antennaein the Antennae

• Wilson et al. 2000, ApJ

NeIIINeII

PAH

Complex mid-IR spectra Complex mid-IR spectra in the Antennaein the Antennae

• Wilson et al. 2000, ApJ

PAH NeII

Mid-IR Spectroscopy with JWSTMid-IR Spectroscopy with JWST

• Is the hot continuum source in the Antennae co-located with the strong NeIII emission?

• 12 microns: 0.5” = 50 pc– Can resolve an individual molecular cloud (100

pc), but not a cluster-forming core (1 pc)

• Extended sources may need small spectroscopic mosaics

• Can we locate other targets with rising continuum in Antennae? M51? Etc?

Comparing the Antennae peak with Comparing the Antennae peak with the R136 star cluster in the LMCthe R136 star cluster in the LMC

Indebetouw et al 2009, ApJ Brandl et al. 2009, ApJ

10 um 30 um10 um 30 um

SummarySummary• MIRI on JWST has great promise for studying

individual star and star cluster formation, both in our own Galaxy and in other galaxies

• Great synergies between JWST and ALMA for high resolution imaging and spectroscopy!

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