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Titolo:
Lithium and mass loss in massive AGB stars in the Large Magellanic Cloud
Autore:
Ventura, P; DAntona, F; Mazzitelli, I;
Indirizzi:
Osservatorio Astron Roma, I-00040 Monte Porzio Catone, Rome, Italy Osservatorio Astron Roma Monte Porzio Catone Rome Italy I-00040 me, Italy CNR, Ist Astrofis Spaziale, I-00133 Rome, Italy CNR Rome Italy I-00133CNR, Ist Astrofis Spaziale, I-00133 Rome, Italy
Titolo Testata:
ASTRONOMY AND ASTROPHYSICS
fascicolo: 2, volume: 363, anno: 2000,
pagine: 605 - 616
SICI:
0004-6361(200011)363:2<605:LAMLIM>2.0.ZU;2-V
Fonte:
ISI
Lingua:
ENG
Soggetto:
ASYMPTOTIC GIANT BRANCH; STELLAR TURBULENT CONVECTION; INTERMEDIATE-MASS; CARBON STARS; S-PROCESS; FULL SPECTRUM; RED GIANTS; LOSS RATES; EVOLUTION; MODEL;
Keywords:
stars : AGB and post-AGB; stars : evolution; stars : mass-loss;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
62
Recensione:
Indirizzi per estratti:
Indirizzo: Ventura, P Osservatorio Astron Roma, I-00040 Monte Porzio Catone, Rome, Italy Osservatorio Astron Roma Monte Porzio Catone Rome Italy I-00040
Citazione:
P. Ventura et al., "Lithium and mass loss in massive AGB stars in the Large Magellanic Cloud", ASTRON ASTR, 363(2), 2000, pp. 605-616

Abstract

The aim of this work is to use full evolutionary models to derive observational constraints on the mass loss rate of the upper Asymptotic Giant Branch (AGB) stars. The observations used to constrain the models are: i) the relative number of luminous Lithium rich AGBs in the Magellanic Clouds, with respect to the total number of AGBs populating the luminosity range -6 greater than or equal to M-bol greater than or equal to -7; ii) the s-process enhancement of the same sample. The calibration of the mass loss rate we obtain gives feedbacks on the interpretation of observational data of obscuredAGBs, and allows us to provide consistent lithium yields for these stars, to be used to constrain the galactic chemical evolution. We find that: a) we can put lower and upper limits to the mass loss rate during the AGE phase; b) after a "visible" phase, the models evolve into a phase of strong mass loss, which can be identified with the obscured OH/IR stars accessible only in the infrared; the models well reproduce the Period-M-bol loci of the obscured AGBs (Wood et al. 1992); c) the most massive AGBs (mass of progenitors, hereinafter M-ZAMS, similar to 6M.) are extremely luminous (M-bol similar to -7.2 to -7.5); d) The lithium yield increases with the mass loss rate and with the total stellar mass, being maximum for AGEstars close to the lower limit for carbon semi-degenerate ignition. However, the mass loss calibration obtained in this work implies that massive AGBs do not contribute significantly to the lithium enrichment of the interstellar medium.

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Documento generato il 05/12/20 alle ore 06:49:16