The most metal-rich asymptotic giant branch stars
  We present new stellar evolutionary sequences of very metal-rich stars
evolved with the Monash Stellar Structure code and with MESA. The Monash models
include masses of $1-8M_{\odot}$ with metallicities $Z=0.04$ to $Z=0.1$ and are
evolved from the main sequence to the thermally-pulsing asymptotic giant branch
(AGB). These are the first $Z=0.1$ AGB models in the literature. The MESA
models include intermediate-mass models with $Z=0.06$ to $Z=0.09$ evolved to
the onset of the thermally-pulsing phase. Third dredge-up only occurs in
intermediate-mass models $Z \le 0.08$. Hot bottom burning (HBB) shows a weaker
dependence on metallicity, with the minimum mass increasing from 4.5$M_{\odot}$
for $Z=0.014$ to $\approx 5.5 M_{\odot}$ for Z = 0.04, $6M_{\odot}$ for $ 0.05
\le Z \le 0.07$ and above 6.5$ M_{\odot}$ for $Z\ge 0.08$. The behaviour of the
$Z=0.1$ models is unusual; most do not experience He-shell instabilities owing
to rapid mass-loss on the early part of the AGB. Turning off mass-loss produces
He-shell instabilities, however thermal pulses are weak and result in no third
dredge-up. The minimum mass for carbon ignition is reduced from 8$M_{\odot}$
for $Z=0.04$ to 7$M_{\odot}$ for $Z=0.1$, which implies a reduction in the
minimum mass for core-collapse supernovae. MESA models of similarly high
metallicity ($Z=0.06 - 0.09$) show the same lowering of the minimum mass for
carbon ignition: carbon burning is detected in a $6 M_{\odot}$ model at the
highest metallicity ($Z=0.09$) and in all $7 M_{\odot}$ models with $Z \ge
0.06$. This demonstrates robustness of the lowered carbon burning threshold
across codes.
