LITHIUM ABUNDANCES IN CARBON-ENHANCED METAL-POOR STARS

Carbon-enhanced metal-poor (CEMP) stars are believed to show the chemical imprints of more massive stars (M [gap] 0.8 M sub([middot in circle])) that are now extinct. In particular, it is expected that the observed abundance of Li should deviate in these stars from the standard Spite lithium plateau...

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Bibliographic Details
Published in:The Astrophysical journal 2012-05, Vol.751 (1), p.1-16
Main Authors: MASSERON, Thomas, JOHNSON, Jennifer A, LUCATELLO, Sara, KARAKAS, Amanda, PLEZ, Bertrand, BEERS, Timothy C, CHRISTLIEB, Norbert
Format: Article
Language:English
Subjects:
ABSORPTION SPECTRA
Abundance
Astronomical models
ASTRONOMY
ASTROPHYSICS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
BINARY STARS
CARBON
CARBON STARS
Depletion
DILUTION
Earth, ocean, space
ELEMENT ABUNDANCE
EMISSION SPECTRA
Evolutionary
Exact sciences and technology
LITHIUM
LUMINOSITY
Metallicity
ROTATION
Spectroscopy
Stars
TELESCOPES
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Summary:Carbon-enhanced metal-poor (CEMP) stars are believed to show the chemical imprints of more massive stars (M [gap] 0.8 M sub([middot in circle])) that are now extinct. In particular, it is expected that the observed abundance of Li should deviate in these stars from the standard Spite lithium plateau. We study here a sample of 11 metal-poor stars and a double-lined spectroscopic binary with -1.8 < [Fe/H] < -3.3 observed with the Very Large Telescope/UVES spectrograph. Among these 12 metal-poor stars, there are 8 CEMP stars for which we measure or constrain the Li abundance. In contrast to previous arguments, we demonstrate that an appropriate regime of dilution permits the existence of "Li-Spite plateau and C-rich" stars, whereas some of the "Li-depleted and C-rich" stars call for an unidentified additional depletion mechanism that cannot be explained by dilution alone. We find evidence that rotation is related to the Li depletion in some CEMP stars. Additionally, we report on a newly recognized double-lined spectroscopic binary star in our sample. For this star, we develop a new technique from which estimates of stellar parameters and luminosity ratios can be derived based on a high-resolution spectrum alone, without the need for input from evolutionary models.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/751/1/14