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A&A 371, 152-173 (2001)
DOI: 10.1051/0004-6361:20010309
Zero-metallicity stars
I. Evolution at constant mass
P. Marigo1, L. Girardi1, C. Chiosi1 and P. R. Wood21 Dipartimento di Astronomia, Università di Padova, Vicolo dell'Osservatorio 2, 35122 Padova, Italia
2 Mount Stromlo and Siding Spring Observatories, Australian National University, Private Bag, Weston Creek PO, ACT 2611, Australia
(Received 12 December 2000 / Accepted 28 February 2001)
Abstract
We present extensive evolutionary models of stars
with initial zero-metallicity, covering a large range of initial masses
(i.e.
). Calculations are carried
out at constant mass, with updated input physics, and applying an
overshooting scheme to convective boundaries. The nuclear network
includes all the important reactions of the p-p chain,
CNO-cycle and 
-captures, and is solved by means
of a suitable semi-implicit method. The evolution is followed up to the
thermally pulsing AGB in the case of low- and intermediate-mass stars,
or to the onset of carbon burning in massive stars.
The main evolutionary features of these models are discussed,
also in comparison with models of non-zero metallicity. Among
several interesting aspects, particular
attention has been paid to describe: i) the first synthesis of
12C inside the stars, that may suddenly trigger the CNO-cycle
causing particular evolutionary features; ii) the pollution of
the stellar surface by the dredge-up events, that are effective
only within particular mass ranges; iii) the mass limits which conventionally
define the classes of low-, intermediate-, and high-mass stars on the
basis of common evolutionary properties,
including the upper mass limit for the achievement
of super-Eddington luminosities before C-ignition in the high-mass regime;
and iv) the expected pulsational properties of zero-metallicity stars.
All relevant information referring to the evolutionary tracks
and isochrones is made available in computer-readable
format.
Key words: stars: evolution -- stars: interiors -- stars: Hertz sprung -- Russell (HR) diagram -- stars: low-mass
Offprint request: P. Marigo, marigo@pd.astro.it
SIMBAD Objects
© ESO 2001