SETI public: The abundance of metals in stars with planets - 2 papers

>Date: Wed, 6 Apr 2005 18:21:04 GMT   (33kb) > >Title: Spectroscopic metallicities for planet-host stars: extending the samples >Authors: N.C. Santos (1,2), G. Israelian (3), M. Mayor (2), J.P. Bento (1), >   P.C. Almeida (1), S.G. Sousa (1), A. Ecuvillon (3) ((1) Centro de Astronomia >   e Astrofisica da Universidade de Lisboa, (2) Observatoire de Geneve, (3) >   Instituto de Astrofisica de Canarias) >Comments: Accepted for publication in A&A >\\ >   In this paper we present stellar parameters and metallicities for 28 >planet-host stars, as well as for a large volume-limited sample of 54 stars not >known to be orbited by any planetary-mass companion. These stars add to the >results presented in our previous series of papers, providing two large and >uniform samples of 119 planet-hosts and 95 ``single'' stars with accurate >stellar parameters and [Fe/H] estimates. The analysis of the results further >confirms that stars with planets are metal-rich when compared with average >field dwarfs. Important biases that may compromise future studies are also >discussed. Finally, we compare the metallicity distributions for single >planet-hosts and planet-hosts in multiple stellar systems. The results show >that a small difference cannot be excluded, in the sense that the latter sample >is slighly overmetallic. More data are needed, however, to confirm the validity >of this correlation. >\\ ( http://arXiv.org/abs/astro-ph/0504154 ,  33kb) >------------------------------------------------------------------------------

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>\\ >Paper: astro-ph/0504157 >Date: Wed, 6 Apr 2005 18:35:19 GMT   (104kb) > >Title: Abundances of Na, Mg and Al in stars with giant planets >Authors: P. Beirao (1), N.C. Santos (1,2), G. Israelian (3), M. Mayor (2) ((1) >   Centro de Astronomia e Astrofisica da Universidade de Lisboa, (2) >   Observatoire de Geneve, (3) Instituto de Astrofisica de Canarias) >Comments: Accepted for publication in A&A >\\ >   We present Na, Mg and Al abundances in a set of 98 stars with known giant >planets, and in a comparison sample of 41 ``single'' stars. The results show >that the [X/H] abundances (with X = Na, Mg and Al) are, on average, higher in >stars with giant planets, a result similar to the one found for iron. However, >we did not find any strong difference in the [X/Fe] ratios, for a fixed [Fe/H], >between the two samples of stars in the region where the samples overlap. >Finally, the data was used to study the Galactic chemical evolution trends for >Na, Mg and Al, and to discuss the possible influence of planets on this >evolution. The results, in general similar to the ones obtained by other >authors, show that the [X/Fe] ratios all decrease as a function of metallicity >up to solar values. While for Mg and Al this trend then becomes relatively >constant, for Na we find indications of an upturn up to [Fe/H] values close to >0.25dex. For metallicities above this value the [Na/Fe] becomes constant. >\\ ( http://arXiv.org/abs/astro-ph/0504157 ,  104kb) >------------------------------------------------------------------------------

>Paper (*cross-listing*): gr-qc/0502099

>replaced with revised version Wed, 6 Apr 2005 13:25:36 GMT   (18kb) > >Title: Phantom energy traversable wormholes >Authors: Francisco S. N. Lobo >Comments: 9 pages, Revtex4. V2: Considerable comments and references added, no >   physics changes, now 10 pages. Accepted for publication in Physical Review D >\\ ( http://arXiv.org/abs/gr-qc/0502099 ,  18kb) >------------------------------------------------------------------------------