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The GRAMS Evolved Star Mass-Loss Models: CMDs, CCDs, and Stellar Population Analysis for the LMC. Benjamin Sargent Collaborators: S. Srinivasan, M. Meixner, SAGE, and SAGE-Spec teams Mass-Loss Return from Stars to Galaxies Workshop May 20, 2010.

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the grams evolved star mass loss models cmds ccds and stellar population analysis for the lmc

The GRAMS Evolved Star Mass-Loss Models: CMDs, CCDs, and Stellar Population Analysis for the LMC

Benjamin Sargent

Collaborators: S. Srinivasan, M. Meixner,

SAGE, and SAGE-Spec teams

Mass-Loss Return from Stars to Galaxies Workshop

May 20, 2010

sage surveying the agents of a galaxy s evolution
SAGE: Surveying the Agents of a Galaxy’s Evolution
  • Above left, IRAC and MIPS surveys of 7°x7º area of LMC, Spitzer Legacy program (Meixner et al 2006, AJ, 132, 2268)
  • Above right, Blum et al (2006, AJ, 132, 2034)
finding dust properties
Finding Dust Properties
  • SEDs: U, B, V, I from MCPS (Zaritsky et al 1997); J, H, Ks from 2MASS (Skrutskie et al 2006), IRAC and MIPS-24 from SAGE
  • Above, SED of oxygen-rich (O-rich) AGB star; 2Dust (Ueta & Meixner 2003) model of O-rich AGB (Sargent et al 2010)
  • Below, SED of carbon-rich (C-rich) AGB star; 2Dust model from Srinivasan et al (2010, submitted to A&A)
grams g rid of r ed supergiant and a gb m odel s
GRAMS: Grid of Red supergiant and AGB ModelS
  • spherical symmetry, Rmax/Rmin=1000, Kim et al (1994) size distribution: n(a) = C*a-3.5exp[-a/a0]
  • O-rich dust: O-deficient silicates (Ossenkopf et al 1992), a0=0.01m, amin=0.1m
  • O-rich models: Teff = 2100-4700K, log10(L)=3-6, 10=0.0001-32, Rmin=3, 7, 11, 15
  • C-rich dust: 90% amorph. carbon (Zubko et al. 1996), 10% SiC (Pégourié 1988), a0=0.1m, amin=1m. 88/12 C/SiC for previous model
  • C-rich models: Teff = 2600-3500K, log10(L)=3-5.5, 11.3=0.001-1, Rmin=1.5, 4.5, 7, 12
cmds o rich model grid
CMDs: O-rich model grid
  • Color-magnitude diagram (CMD)
  • Good coverage for SAGE and SAGE-Spec O-rich stars
  • Grid misses for bluest O-AGBs, large errors for faintest sources
cmds c rich model grid
CMDs: C-rich model grid
  • Same CMD, but with C-rich grid and C-AGBs
color color diagram o rich grid
Color-color diagram: O-rich grid
  • Right, from Sargent et al (2010b, in prep)
  • O-AGBs, RSGs, and extreme AGBs identified by Woods et al (2010, in prep) as O-rich in SAGE-Spec (Kemper et al 2010, submitted) well-fit by models, but confusion with C-rich AGBs at K-[3.6] > 1.5
color color diagram c rich grid
Color-color diagram: C-rich grid
  • Above, from Srinivasan et al (2010, in prep)
  • Better coverage of extreme AGBs than O-rich
sed fitting
SED-fitting
  • Currently using 2 minimization routine in IDL (S. Srinivasan)
  • Eventually adapt Robitaille et al. (2006) YSO SED-fitter to GRAMS model grid
  • O-rich AGBs and RSGs typically fit well by O-rich grid
sed fitting dust chemistry
SED-fitting & Dust Chemistry
  • Right: An SED for an extreme AGB star candidate
  • Best-fit models from both O-rich and C-rich grids shown on figure
  • C-rich model (in green) provides much better fit, especially for IRAC bands
stellar masses and ages
Stellar Masses and Ages
  • Right: Marigo et al. (2008) isochrones for Z=0.008 (LMC)
  • O-rich AGBs and RSGs (Teff, L) from SED-fitting overplotted
  • Points under 104 LSun & Teff < 103.5 K due to variability (A. Lançon, priv. communication)?
o rich grid stellar masses
O-rich Grid & Stellar Masses
  • Above right: histogram of stellar mass from fitting to Marigo et al (2008) Z=0.008 isochrones
  • Below right: [24] vs. [8.0]-[24] CMD
  • O-rich AGB stars with M > 2.7 MSun typically on “bright” branch of O-rich AGBs
stellar populations applications
Stellar Populations applications?
  • MLR, Teff, L come from SED-fitting
  • Mass and age from Marigo et al 2008 isochrones
o c extreme agb mass loss
O-, C-, & extreme AGB Mass-Loss
  • Right, Srinivasan et al (2009, AJ, 137, 4810)
  • 0.14, 0.24, & 2.4 x 10-5 MSun/yr total, from O-, C-, & extreme AGBs, respectively
  • From SED-fitting, 0.64, 0.14, & 2.3 x 10-5 MSun/yr total, respectively (about 18000 O-AGBs, 7000 C-AGBs, & 1400 extremes)
  • 0.048 x 10-5 MSun/yr from ~110 RSGs
conclusions
Conclusions
  • Spitzer CMDs and CCDs better separate O- and C-rich evolved stars than previous surveys allowed, but SED-fitting is quite powerful in this regard.
  • Applications to stellar populations studies.
  • Extreme AGBs produce most dust, but how many C-rich versus O-rich? Probably most have carbon dust. But, per star, RSGs really pull their weight in returning mass …
  • AGB/RSG contribution to LMC mass budget comparable to SNe contribution? Masaaki Otsuka will discuss SNe contribution tomorrow morning.
  • Stay tuned for further SAGE work on SMC (Karl Gordon, Martha Boyer, et al) and LMC (Sundar Srinivasan, myself, et al)
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