1999A&A...348..211N


Query : 1999A&A...348..211N

1999A&A...348..211N - Astronomy and Astrophysics, volume 348, 211-221 (1999/8-1)

Isotopic lithium abundances in five metal-poor disk stars.

NISSEN P.E., LAMBERT D.L., PRIMAS F. and SMITH V.V.

Abstract (from CDS):

High resolution (R≃110000), very high S/N spectra centered on the 6707.8 Å LiI line have been obtained with the ESO Coude Echelle Spectrometer for five, metal-poor (-0.8<[Fe/H]←0.6) disk stars in the turnoff region of the HR-diagram. The instrumental and stellar atmospheric line broadening have been determined from two unblended iron lines and used in a model atmosphere synthesis of the profile of the LiI line as a function of the lithium isotope ratio. This has led to a detection of 6Li in HD 68284 and HD 130551 with 6Li/7Li≃0.05, whereas the other stars, HR 2883, HR 3578 and HR 8181, have 6Li/7Li close to zero. By comparing Teff-values and absolute magnitudes based on Hipparcos parallaxes with recent stellar evolutionary tracks, the masses of the stars have been derived. It is shown that the two stars with 6Li present have a significantly higher mass, M/M ≃1.05, than the other three stars for which values between 0.85 and 1.0 M are obtained. The results are discussed in terms of models for the galactic evolution of the light elements and depletion of the lithium isotopes in stellar envelopes. It is shown that the measured 6Li abundances are in agreement with standard cosmic ray production of 6Li in the galactic disk and a moderate depletion (0.5dex) in the stars. Recent models for the evolution of 6Li including α+ α fusion reactions and predicting a high lithium isotopic ratio, 6Li/7Li≃0.3 at [Fe/H]=-0.6, require a high degree of 6Li depletion (≃1.0dex) to fit the observations. Furthermore, these models imply a 7Li abundance about 0.2dex higher than observed for metal-poor disk stars.

Abstract Copyright:

Journal keyword(s): stars: abundances - stars: atmospheres - stars: fundamental parameters - stars: interiors - ISM: cosmic rays

Simbad objects: 7

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Number of rows : 7
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 HD 59984 PM* 07 32 05.7629164512 -08 52 52.775251032   6.431 5.916     G0VFe-1.6CH-0.5 200 0
2 HD 68284 PM* 08 11 49.5873390000 +04 16 28.326641232   8.28 7.75     F7/8V 88 0
3 HD 76932 PM* 08 58 43.9327642391 -16 07 57.817644364 6.47 6.39 5.86     G2VFe-1.8CH-1 379 0
4 HD 84937 PM* 09 48 56.0992891997 +13 44 39.326709913 8.49 8.68 8.32 7.97 7.70 F8Vm-5 751 0
5 HD 130551 PM* 14 51 31.7225624616 -60 55 50.851034904   9.068 8.751     F5V 97 0
6 HD 338529 PM* 19 32 31.9104668184 +26 23 26.117367216   9.72   9.2   B5 203 0
7 * gam Pav PM* 21 26 26.6049826473 -65 21 58.313057521 4.57 4.70 4.22 3.75 3.45 F9VFe-1.4CH-0.7 394 0

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2022.05.20-18:10:23

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