The Giant Branches Stellar evolution of RGB and AGB stars Importance, features, uncertainties Achim Weiss (Max-Planck-Institut für Astrophysik, Garching)
M5 (Rosenberg et al. 2000) Giant Branches MACHO data on LMC (260,000 stars); right: variable stars removed ~ AGB (Alves et al. 1999)
Bumps, Clumps, Tips
Features along the Giant Branches (from C. Gallart 1999; for LMC population)
RGB bump Convective envelope H shell H-shell encounters Habundance step NGC 5824 (Zoccali et al. 1999)
The ABG bump found by Alcock et al. (1997) in MACHO-CMDs of LMC explanation by Gallart: re-ignition of H-shell after 2nd dredge-up phase (C. Gallart 1999; using Padova library)
The Red Clump Evolution during core He-burning: solid: 70% of core He-lifetime dashed: 75-85%; dotted: 85-99% long-dashed: initial phase (<12%) (Girardi 1999) mass along che-sequence RC in LMC (Romaniello et al 2000)
The RGB tip NGC300 Bellazini & Ferraro (2001) Rizzi et al. (2006); Araucaria-Project
clumps and bumps are used for: distance indicator (red clump and RGB tip) physics of internal cooling in giants (RGB tip) modelling extra-mixing (RGB bump) population indicator (red clump) age indicator (RGB bump)...
Questions: the brightness of the bump(s)? the constancy of mean clump brightness? the brightness of the tip of the RGB? dependencies on age or/and metallicity?...
Example for age fitting problem NGC4833 Fitting age indicators: red: ΔVTO-ZAHB and similar TO-based age indicators blue: ΔVbump-ZAHB and similar bumpbased indicators BaSTI models: red: TO-based only blue: with ΔVbump-ZAHB included (Meissner & Weiss 2006)
Temperatures and Colours
The RGB temperature Teff: 4 Gyr amount to < 50 K on RGB! Garching models (Z=0.0003; with diffusion) BaSTI models (Z=0.002)
... as a metallicity indicator 10 RGB fiducials from Valenti et al. (2004); calibration of RGB photometric indices as function of metallicity
The AGB simulation LMC 2MASS observations (Marigo et al, 2003)
Population synthesis rest AGB RGB Contribution of various evolutionary phases to integrated flux and colours. AGB: dot-short dash line (red) in left figure; blue line in right one (Bruzual & Charlot 1993; and Bruzual 2009, private communication)
Nucleosynthesis and Mixing
Extra-mixing along the RGB position of RGB-bump MS low-rgb up-rgb HB 1st dredge-up -2 [Fe/H] -1 (Gratton et al. 2000) this reduction unexplained by 1DUP What is the mechanism?
Nucleosynthesis on the AGB (including 3rd dredge-up, rotation, convection w. overshooting,...) Ventura and D'Antona (2005): influence of convection (5 M, Z=0.001) on Na abundance in ejecta as function of decreasing stellar mass plus nuclear rates uncertainties (Izzard et al. 2007): Yield ranges: Na: 0.4 100 24 Mg: 0.8 48 25 Mg: 0.9 1.7 26 Mg: 0.7-1.1 26 Al: 0.01 3 27 Al: 0.4-6.2 23
Mass loss, stellar yields, post-gb evolution
Mass loss on the RGB NGC 6791 Are these He-WD resulting from high mass loss in cluster with [Fe/H]=+0.4? (Kalirai et al. 2007) Can the HB morphology of GC be explained by a ΔM-[Fe/H] relation? (Dotter 2008)
... and on the AGB Salaris et al. (2009) Initial-final mass relation: integrated effect of mass loss along the AGB 60 Fe and 26 Al yields (Lugaro & Karakas 2008)
(courtesy L. Siess) mass loss and end products is mass loss preventing evolution to SAGB stars and of ONe WDs and EC SNe? (courtesy L. Siess)
more subjects... pulsations: connection to mass loss on the RGB: way to discriminate populations with different Y? binarity: mass transfer chemical enrichment evolution: at extreme metallicities individual element abundances
Conclusion let the workshop begin...