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 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 SEDs: U, B, V, I from MCPS (Zaritsky et al 1997); J, H, K s 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: Grid of Red supergiant and AGB ModelS spherical symmetry, R max /R min =1000, Kim et al (1994) size distribution: n(a) = C*a -3.5 exp[-a/a 0 ] O-rich dust: O-deficient silicates (Ossenkopf et al 1992), a 0 =0.01  m, a min =0.1  m O-rich models: T eff = K, log 10 (L)=3-6,  10 = , R min =3, 7, 11, 15 C-rich dust: 90% amorph. carbon (Zubko et al. 1996), 10% SiC (Pégourié 1988), a 0 =0.1  m, a min =1  m. 88/12 C/SiC for previous model C-rich models: T eff = K, log 10 (L)=3- 5.5,  11.3 = , R min =1.5, 4.5, 7, 12

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 Same CMD, but with C-rich grid and C-AGBs

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 Above, from Srinivasan et al (2010, in prep) Better coverage of extreme AGBs than O-rich

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 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 Right: Marigo et al. (2008) isochrones for Z=0.008 (LMC) O-rich AGBs and RSGs (T eff, L) from SED-fitting overplotted Points under 10 4 L Sun & T eff < K due to variability (A. Lançon, priv. communication)?

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 M Sun typically on “bright” branch of O-rich AGBs

Stellar Populations applications? MLR, T eff, L come from SED-fitting Mass and age from Marigo et al 2008 isochrones

O-, C-, & extreme AGB Mass- Loss Right, Srinivasan et al (2009, AJ, 137, 4810) 0.14, 0.24, & 2.4 x M Sun /yr total, from O-, C-, & extreme AGBs, respectively From SED-fitting, 0.64, 0.14, & 2.3 x M Sun /yr total, respectively (about O-AGBs, 7000 C-AGBs, & 1400 extremes) x M Sun /yr from ~110 RSGs

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)