A new synthetic model for asymptotic giant branch stars

Abstract

We present a synthetic model for thermally pulsing asymptotic giant branch (TPAGB) evolution constructed by fitting expressions to full evolutionary models in the metallicity range 0.0001 [less than or equal to] Z [less than or equal to] 0.02. Our model includes parametrizations of third dredge-up and hot-bottom burning with mass and metallicity. The Large Magellanic Cloud and Small Magellanic Cloud carbon star luminosity functions are used to calibrate third dredge-up. We calculate yields appropriate for galactic chemical evolution models for [superscript 1]H, [superscript 4]He, [superscript 12]C, [superscript 13]C, [superscript 14]N, [superscript 15]N, [superscript 16]O and [superscript 17]O. The initial–final mass relation is examined for our stars and found to fit to within 0.1 M[subscript circled dot] of the observations. We also reproduce well the white dwarf mass function for masses above about 0.58 M[subscript circled dot]. The new model is to be implemented in a rapid binary star evolution code.