E. Delgado Mena, G. Israelian, J. I. González Hernández, N. C. Santos, R. Rebolo
We present new UVES spectra of a sample of 15 cool unevolved stars with and
without detected planetary companions. Together with previous determinations,
we study Be depletion and possible differences in Be abundances between both
groups of stars. We obtain a final sample of 89 and 40 stars with and without
planets, respectively, which covers a wide range of effective temperatures,
from 4700 K to 6400 K, and includes several cool dwarf stars for the first
time. We determine Be abundances for these stars and find that for most of them
(the coolest ones) the BeII resonance lines are often undetectable, implying
significant Be depletion. While for hot stars Be abundances are aproximately
constant, with a slight fall as Teff decreases and the Li-Be gap around 6300 K,
we find a steep drop of Be content as Teff decreases for Teff < 5500 K,
confirming the results of previous papers. Therefore, for these stars there is
an unknown mechanism destroying Be that is not reflected in current models of
Be depletion. Moreover, this strong Be depletion in cool objects takes place
for all the stars regardless of the presence of planets, thus, the effect of
extra Li depletion in solar-type stars with planets when compared with stars
without detected planets does not seem to be present for Be, although the
number of stars at those temperatures is still small to reach a final
conclusion.
View original:
http://arxiv.org/abs/1111.3495
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