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Titolo:
Observational tests and predictive stellar evolution
Autore:
Young, PA; Mamajek, EE; Arnett, D; Liebert, J;
Indirizzi:
Univ Arizona, Steward Observ, Tucson, AZ 85721 USA Univ Arizona Tucson AZUSA 85721 na, Steward Observ, Tucson, AZ 85721 USA
Titolo Testata:
ASTROPHYSICAL JOURNAL
fascicolo: 1, volume: 556, anno: 2001,
parte:, 1
pagine: 230 - 244
SICI:
0004-637X(20010720)556:1<230:OTAPSE>2.0.ZU;2-P
Fonte:
ISI
Lingua:
ENG
Soggetto:
ULTRAVIOLET RADIAL-VELOCITIES; THERMONUCLEAR REACTION-RATES; SPECTROSCOPIC BINARY ORBITS; ETA-CHAMAELEONTIS CLUSTER; APSIDAL MOTION TEST; ECLIPSING BINARIES; WIDE-RANGE; COMPRESSIBLE CONVECTION; TURBULENT CONVECTION; OPACITY MEASUREMENTS;
Keywords:
atomic processes; binaries : eclipsing; hydrodynamics; stars : evolution; stars : fundamental parameters;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
78
Recensione:
Indirizzi per estratti:
Indirizzo: Young, PA Univ Arizona, Steward Observ, 933 N Cherry Ave, Tucson, AZ 85721USA Univ Arizona 933 N Cherry Ave Tucson AZ USA 85721 , AZ 85721 USA
Citazione:
P.A. Young et al., "Observational tests and predictive stellar evolution", ASTROPHYS J, 556(1), 2001, pp. 230-244

Abstract

We compare 18 binary systems with precisely determined radii and masses from 23 to 1.1 M-. and stellar evolution models produced with our newly revised code TYCHO. "Overshooting" and rotational mixing were suppressed in order to establish a baseline for isolating these and other hydrodynamic effects. Acceptable coeval fits are found for 16 pairs without optimizing for heavy-element or helium abundance. The precision of these tests is limited by the accuracies of the observed effective temperatures. High-dispersion spectra and detailed atmospheric modeling should give more accurate effective temperatures and heavy-element abundances. PV Cas, a peculiar early A system, EK Cep B, a known post-T Tauri star, and RS Cha, a member of a young OB association, are matched by pre-main-sequence models. Predicted mass loss agrees with upper limits from IUE for CW Cep A and B. Relatively poor fits are obtained for binaries having at least one component in the mass range 1.7< M/M-. < 2.6, whose evolution is sensitive to mixing. These discrepanciesare robust and consistent with additional mixing in real stars. The predicted apsidal motion implies that massive star models are systematically lesscentrally condensed than the real stars. If these effects are due to overshooting, then the overshooting parameter alpha (OV) increases with stellar mass. The apsidal motion constants are controlled by radiative opacity under conditions close to those directly measured in laser experiments, making this test more stringent than possible before.

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Documento generato il 26/11/20 alle ore 08:01:26