Bibcode
Ventura, P.; Stanghellini, L.; Dell'Agli, F.; García-Hernández, D. A.; Di Criscienzo, M.
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society, Volume 452, Issue 4, p.3679-3688
Fecha de publicación:
10
2015
Número de citas
28
Número de citas referidas
22
Descripción
We used a new generation of asymptotic giant branch (AGB) stellar models
that include dust formation in the stellar winds to find the links
between evolutionary models and the observed properties of a homogeneous
sample of Large Magellanic Cloud (LMC) planetary nebulae (PNe).
Comparison between the evolutionary yields of elements such as CNO and
the corresponding observed chemical abundances is a powerful tool to
shed light on evolutionary processes such as hot bottom burning (HBB)
and third dredge-up (TDU). We found that the occurrence of HBB is needed
to interpret the nitrogen-enriched (log (N/H) + 12 > 8) PNe. In
particular, N-rich PNe with the lowest carbon content are nicely
reproduced by AGB models of mass M ≥ 6 M⊙, whose
surface chemistry reflects the pure effects of HBB. PNe with log (N/H) +
12 < 7.5 correspond to ejecta of stars that have not experienced HBB,
with initial mass below ˜3 M⊙. Some of these stars
show very large carbon abundances, owing to the many TDU episodes
experienced. We found from our LMC PN sample that there is a threshold
to the amount of carbon accumulated at AGB surfaces, log (C/H) + 12 <
9. Confirmation of this constraint would indicate that, after the C-star
stage is reached, AGBs experience only a few thermal pulses, which
suggests a rapid loss of the external mantle, probably owing to the
effects of radiation pressure on carbonaceous dust particles present in
the circumstellar envelope. The implications of these findings for AGB
evolution theories and the need to extend the PN sample currently
available are discussed.
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