4,628 research outputs found
A comparative study of two 47 Tuc giant stars with different s-process enrichment
Here we aim to understand the origin of 47 Tuc's La-rich star Lee 4710. We
report abundances for O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Co, Ni, Zn, Y, Zr,
Ba, La, Ce, Pr, Nd, and Eu, and present a detailed abundance analysis of two 47
Tuc stars with similar stellar parameters but different slow neutron-capture
(s-)process enrichment. Star Lee 4710 has the highest known La abundance ratio
in this cluster ([La/Fe] = 1.14), and star Lee 4626 is known to have normal
s-process abundances (e.g., [Ba/Eu]). The nucleosynthetic pattern of
elements with Z56 for star Lee 4710 agrees with the predicted yields
of a asymptotic giant branch (AGB) star. Therefore, Lee 4710 may
have been enriched by mass transfer from a more massive AGB companion, which is
compatible with its location far away from the center of this relatively
metal-rich ([Fe/H]) globular cluster. A further analysis comparing
the abundance pattern of Lee 4710 with data available in the literature reveals
that nine out of the 47 Tuc stars previously studied show strong
s-process enhancements that point towards later enrichment by more massive AGB
stars.Comment: ApJL in press. 6 pages, 4 figure
Effects of an extra gauge boson on the top quark decay
The effects of an extra gauge boson with family nonuniversal fermion
couplings on the rare top quark decay gamma10^{-8}m_{Z'}=500Z'B(t --> c
\gamma)\sim 10^{-6}m_{Z'}=1$ TeV.Comment: New paragraphs included to clarify our results, conclusion remains
unchange
Inference of mixed information in Formal Concept Analysis
Negative information can be considered twofold: by means
of a negation operator or by capturing the absence of information. In
this second approach, a new framework have to be developed: from the syntax to the semantics, including the management of such generalized knowledge representation. In this work we traverse all these issues in the framework of formal concept analysis, introducing a new set of inference rules to manage mixed (positive and negative) attributes.TIN2014-59471-P of the Science and Innovation
Ministry of Spain, co-funded by the European Regional Development Fund
(ERDF). UNIVERSIDAD DE MÁLAGA. Campus de Excelencia Internacional Andalucía Tech
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