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Titolo:
Analysis of neutron capture elements in metal-poor stars
Autore:
Mishenina, TV; Kovtyukh, VV;
Indirizzi:
Odessa State Univ, Astron Observ, UA-65014 Odessa, Ukraine Odessa State Univ Odessa Ukraine UA-65014 serv, UA-65014 Odessa, Ukraine Isaac Newton Inst Chile, Odessa Branch, Santiago, Chile Isaac Newton Inst Chile Santiago Chile , Odessa Branch, Santiago, Chile
Titolo Testata:
ASTRONOMY & ASTROPHYSICS
fascicolo: 3, volume: 370, anno: 2001,
pagine: 951 - 966
SICI:
1432-0746(200105)370:3<951:AONCEI>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
GALACTIC CHEMICAL EVOLUTION; S-PROCESS NUCLEOSYNTHESIS; GIANT BRANCH STARS; EFFECTIVE TEMPERATURE SCALE; ELODIE ECHELLE SPECTRA; COOL DWARF STARS; PARAMETERS T-EFF; ATMOSPHERIC PARAMETERS; MASSIVE STARS; ONLINE DETERMINATION;
Keywords:
nucleosynthesis, abundances; stars : abundances; stars : late-type; Galaxy : evolution;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
53
Recensione:
Indirizzi per estratti:
Indirizzo: Mishenina, TV Odessa State Univ, Astron Observ, Shevchenko Pk, UA-65014 Odessa, Ukraine Odessa State Univ Shevchenko Pk Odessa Ukraine UA-65014 ine
Citazione:
T.V. Mishenina e V.V. Kovtyukh, "Analysis of neutron capture elements in metal-poor stars", ASTRON ASTR, 370(3), 2001, pp. 951-966

Abstract

We derived model atmosphere parameters (T-eff, log g, [Fe/H], V-t) for 90 metal-deficient stars (-0.5 < [Fe/H] < -3), using echelle spectra from the ELODIE library (Soubiran et al. 1998). These parameters were analyzed and compared with current determinations by other authors. The study of the following elements was carried out: Mg. Si. Ga, Sr, Y. Ba, La, Ce, Nd, and Eu. The relative contributions of s- and r-processes were evaluated and interpreted through theoretical computations of the chemical evolution of the Galaxy. The chemical evolution models (Pagel & Tautvaisiene 1995, Timmes et al.1995) depict quite well the behaviour of [Si/Fe], [Ca/Fe] with [Fe/H]. Thetrend of [Mg/Fe] compares more favourably with the computations of Pagel &Tautvaisiene: (1995) than those of Timmes et al. (1995). The runs of n-capture elements vs, metallicity are described well both by the model of Pagel& Tautvaisiene (1995, 1997) and by the model of Travaglio ct al. (1999) at(Fe/H] > -1.5, when the matter of the Galaxy is sufficiently homogeneous. The analysis of n-capture element abundances confirms the jump in [Ba/Fe] at [Fe/H]= -2.5. Some stars front our sample at [Fe/H] < -2.0 show a large scatter of Sr, Ba, Y, Ce. This scatter is not caused by the errors in the measurements, and may reflect the inhomogeneous nature of the prestellar medium at early stages of galactic evolution. The matching of [Ba/Fe], [Eu/Fe] vs. [Fe/H] with the inhomogeneous model by Travaglio et al. (2001a) suggests that at [Fe/H] < -2.5, the essential contribution to the n-rich element abundances derives from the r-process. The main sources of these processes may be low mass SN II. The larger dispersion of s-process element abundanceswith respect to a-rich elements may arise both from the birth of metal-poor stars in globular clusters with following different evolutionary paths and (or) from differences in s-element enrichment in Galaxy populations.

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Documento generato il 27/11/20 alle ore 02:13:02