Evolved Stars in Nearby Galaxies with JWST: The DUSTiNGS Pathfinding Surveys Martha Boyer (STScI) & The DUSTiNGS Team
Why AGB Stars? Dust FormaIon Dust affects new star and planet formation. AGB stars may dominate dust production High LuminosiIes Integrated light used to derive galaxy stellar mass and star-formation rate. AGB stars contribute a large fraction of a galaxy s NIR flux. DiagnosIc Tools Distance: (period-luminosity relationship) Metallicity: (ratio of C to M stars) Star-formation History: Intermediate-aged stars
Why AGB Stars? Dust FormaIon Dust affects new star and planet formation. AGB stars may dominate dust production LMC Zhukovska & Henning (2013) Also Schneider et al. (2014) ISM Dust Mass à Gordon et al. (2015) AGB dust producion comes close to explaining all of the ISM dust in the LMC (up to ~40%)
Why AGB Stars? High LuminosiIes Integrated light used to derive galaxy stellar mass and star-formation rate. AGB stars contribute a large fraction of a galaxy s NIR flux. Melbourne et al. (2012) AGB stars contribute up to 70% of a galaxy s 1.6 μm flux at some redshi[s.
Why AGB Stars? Dust FormaIon Dust affects new star and planet formation. AGB stars may dominate dust production High LuminosiIes Integrated light used to derive galaxy stellar mass and star-formation rate. AGB stars contribute a large fraction of a galaxy s NIR flux. AGB phase is difficult to model and poorly understood JWST capabiliies are fantas&c for AGB studies
Srinivasan et al. (2016) AGB stars with JWST JWST filter range Imaging: NIRCam and MIRI imaging filters cover most of the AGB SED Spectroscopy: NIRISS, NIRSpec cover molecular features NIRCam, NIRSpec, MIRI cover key dust features SMC AGB Spectra from Ruffle et al. (2015) SiC Silicate CO C 2 H 2 MgS C star M star
ObservaYonal Constraints Chief Uncertainties Dredge up Mass Loss Observables AGB counts Luminosity Functions Multi-λ flux (SEDs) Dust & molecules Pulsation Subtype classification Small galaxies and early galaxies SMC LMC Massive galaxies Requirements Large AGB population Known metallicity Known distance *Infrared coverage (JWST!) Models: Karakas & La\anzio (2007) Underlying graphic: Iain McDonald
Surveys with JWST NIRCam: 2.2 x5.1 (with gaps) MIRI: 1.2 x1.8 NIRCam mosaic Sextans A ~4 hours to cover central 3 x4 area in Sextans A once with NIRCam (2 filters).
And I And II And III And V And VI And VII And IX And X And XI And XII And XIII And XIV And XV And XVI And XVII And XVIII And XIX And XX And XXI And XXII Antlia Aquarius Bootes I Bootes II Cetus Coma Ber CVn II Hercules Dw IC 10 IC 1613 Leo IV Leo V Leo A Leo T LGS 3 NGC 147 NGC 185 Pegasus dirr Phoenix Pisces II Sag DIG Segue I Segue II Segue III Sextans A Sextans B Tucana UMa II Willman 1 WLM DUSTiNGS DUST in Nearby Galaxies with Spitzer Boyer et al. (2015a) Ø Imaged 50 nearby dwarf galaxies at 3.6 & 4.5 µm with Spitzer Ø Primary goal: Find evidence for dusty AGB stars at low metallicity DUSTiNGS Galaxy Sample Photometry: h\p://irsa.ipac.caltech.edu/data/spitzer/dustings/
DUSTiNGS Problem: star-galaxy separayon. Not a problem with JWST: angular resolu9on is 15.6x be?er at 3.6µm (~0.13 PSF FWHM) SAGE - LMC
DUSTiNGS Results log(age) 8.6 9.0 Boyer et al. (2015b)
DUSTiNGS Results Variable Stars log(age) 8.6 9.0 NGC 147 Sextans A Galaxy half-light radius Boyer et al. (2015b)
Martha Boyer, STScI DUSTiNGS Results Variable Stars >500 dusty AGB stars detected in 19 galaxies by their change in brightness in ~6 months log(age) 8.6 9.0 <5 varagb: NGC 147 Sextans A Galaxy half-light radius And I And II And IX And XIII And XVII Aquarius Cetus Leo A LGS 3 Phoenix >5 varagb: IC 10 IC 1613 NGC 147 NGC 185 Pegasus dirr Sag DIG Sextans A Sextans B WLM (dsph dirr dtrans) Boyer et al. (2015b)
DUSTiNGS: Metal-poor Dust ProducYon Dustier Average dustiness à Dust can form in large amounts in chemically primitive environments. à Dust forms efficiently from the metals produced by the star itself. Boyer et al. (2015b)
DUSTiNGS: Metal-poor Dust ProducYon Dustier Average dustiness à Dust can form in large amounts in chemically primitive environments. à Dust forms efficiently from the metals produced by the star itself. Boyer et al. (2015b)
DUSTiNGS: Metal-poor Dust ProducYon Dustier Average dustiness à Dust can form in large amounts in chemically primitive environments. à Dust forms efficiently from the metals produced by the star itself. Boyer et al. (2015b) JWST can iden&fy dust species
Radial Age Gradients El-Badry et al. (2016) Model PredicIons à Stellar feedback drives older stars to large radii Younger stars concentrated in center FormaYon radius Current radius ObservaIonal Support à Most galaxies show youngest stars in central regions and large halos of RGB stars. Main Seq RGB Gallagher et al. (1998)
DUSTiNGS Radial Gradients RGB AGB Variable AGB ß Tidal feature McQuinn et al. (2017)
DUSTiNGS Radial Gradients ß Tidal feature McQuinn et al. (2017)
DUSTiNGS Radial Gradients Other related result from this paper: The 3.6 μm Ip of the RGB ß Tidal is not feature a reliable distance indicator. McQuinn et al. (2017)
HST: C and M stars HST imaging in select DUSTiNGS fields à Identify C & M stars à increase spectral coverage HST; PI Boyer
HST: C and M stars M Stars C Stars Boyer et al. in prep
Martha Boyer, STScI Boyer et al. (in prep) NIRCam photometry F162M F182M C stars JWST: C & M Stars - M stars - 2600 K Models: Aringer et al. (2009; 2016) F + constant 3300 K - C stars 2600 K HST/WFC3/IR: 1 M stars F127M JWST/NIRCam: F139M F140M F153M F162M F140M F150W 3300 K NIRISS Grism F182M 2 F210M F250M (µm) C and M stars can be separated in NIRCam filters, NIRISS Grism, or NIRSpec F300M 3
Martha Boyer, STScI NIRCam photometry F162M F182M C stars JWST: C & M Stars - M stars - C/M is a Models: metallicity Aringer et al. (2009; 2016) diagnosyc 2600 K F + constant 3300 K - C stars 2600 K HST/WFC3/IR: 1 F127M JWST/NIRCam: F139M F140M F140M F150W 3300 K F153M F162M M stars NIRISS Grism 2 et F182M F210M e.g., Cioni al. (2009)F250M (µm) C and M stars can be separated in NIRCam filters, NIRISS Grism, or NIRSpec F300M 3
JWST Imaging Boyer et al. (2016) See poster Srinivasan et al.
Summary JWST can transform our understanding of AGB stars by dramaycally increasing the sample of AGB stars at low and high metallicity DUSTiNGS idenyfied dusty AGB stars throughout Local Group as a JWST pathfinder More than 500 dusty stars in 19 galaxies down to [Fe/H] = -2.1 Dust forms efficiently even in chemically primiyve environments Most (6/9) galaxies have radially mixed populayons (AGB + RGB) JWST Studies of AGB stars over broad parameter space: Measure bolometric luminosiyes IdenYfy spectral types (metallicity tracer) Study dust composiyon Measure dust-producyon rates JWST can reach AGB stars well beyond the Local Group