Bibcode
Barrado y Navascues, D.; Fernandez-Figueroa, M. J.; Garcia Lopez, R. J.; de Castro, E.; Cornide, M.
Bibliographical reference
Astronomy and Astrophysics, v.326, p.780-792
Advertised on:
10
1997
Journal
Citations
28
Refereed citations
24
Description
We present an extensive study of lithium abundances in dwarf components
of chromospherically active binary stars (CABS). Since most of these
binaries have known radii, masses and ages, this kind of data is
especially useful for comparisons with theoretical models which try to
explain the Li depletion phenomenon. We show that a significant part of
these stars have clear Li overabundances with respect to the typical
values for stars of the same mass and evolutionary stage. These excesses
are evident when comparing our sample of CABS with binary and single
stars belonging to open clusters of different ages, namely Pleiades,
Hyades, NGC 752, M 67 and NGC 188, which have ages ranging from 7x10^7^
to 10^10^yr. The Li excesses are more conspicuous for masses in the
range 0.75-0.95Msun_, indicating that the rate of Li
depletion has been less pronounced in CABS than in single stars. This
phenomenon is interpreted in the context of transport of angular
momentum from the orbit to the stellar rotation due to tidal effects.
This angular momentum transfer would avoid the radial differential
rotation and the associated turbulent mixing of material in the stellar
interior. Other explanations, however, can not be ruled out. This is the
case of transport of material induced by internal gravity waves, which
could be inhibited due to the presence of strong magnetic fields
associated with the effective dynamo in CABS. The confirmed existence of
a relation between Li abundances and the fluxes in CaII H&K lines
can also be accommodated within both scenarios.