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Parameters Teff and L/L⊙ for a Group of λ Bootis Candidate Stars and their Evolutionary Status

Published online by Cambridge University Press:  12 April 2016

M. Gerbaldi ,
J. Zorec ,
F. Castelli  and
R. Faraggiana
M. Gerbaldi
Affiliation:
Institut d’Astrophysique de Paris, 98bis, Bd. Arago, 75014 Paris, France
J. Zorec
Affiliation:
Institut d’Astrophysique de Paris, 98bis, Bd. Arago, 75014 Paris, France
F. Castelli
Affiliation:
CNR-Gruppo Nazionale Astronomia-Unità di Ricerca di Trieste, Via G.B. Tiepolo 11, 34131 Trieste, Italy
R. Faraggiana
Affiliation:
Dipartimento di Astronomia, Via G.B. Tiepolo 11, 34131 Trieste, Italy

Abstract

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The Teff value, according to the definition of this parameter, is computed with the procedure described; the observations are then compared with the flux distribution from Kurucz’ LTE blanketed models for various values of the metallicity parameter [Z/H].

Then we derive the bolometric luminosity L/L⊙ by combining the stellar bolometric flux with the values of the trigonometric parallaxes and of the colour excess found in the literature. These luminosities are then plotted on evolutionary sequences; from the position of some λ Boo stars (ρ Vir and π1 Ori), we argue that their evolutionary stage, if interpreted as that of stars having left the main sequence, is too late to keep the λ Boo abundance anomalies.

These same λ Boo stars, plotted on pre-main sequence evolutionary tracks, would indicate increasing λ Boo character when the stars are approaching the main sequence showing the strongest character in λ Boo and 29 Cyg, the two stars nearest the ZAMS.

Type
IV. Related Stars
Information
International Astronomical Union Colloquium , Volume 138: Peculiar versus Normal Phenomena in A-Type and Related Stars , 1993 , pp. 413 - 417
Copyright
Copyright © Astronomical Society of the Pacific 1993

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