SETI public: Abundances of refractory elements in the atmospheres of stars with

• Previous message: LARRY KLAES: "SETI public: Ultraviolet Radiation Constraints around the Circumstellar Habitable Zones"

Paper: astro-ph/0512219
Date: Thu, 8 Dec 2005 14:43:49 GMT (210kb)

Title: Abundances of refractory elements in the atmospheres of stars with
extrasolar planets

Authors: G. Gilli (1,2), G. Israelian (2), A. Ecuvillon (2), N.C. Santos
(3,4)
and M. Mayor (4) ((1) Dipartimento di Astronomia, Universita degli Studi di
Padova, Italy, (2) IAC, Spain, (3) Observatorio Astronomico de Lisboa,
Portugal, (4) Observatoire de Geneve, Switzerland)

Comments: 15 pages, 11 figures, accepted for publication in A&A. Tables 7-10
are available at www.iac.es/proyect/abuntest<http://www.iac.es/proyect/abuntest>, or in the electronic version
of
the Journal
\\
This work presents a uniform and homogeneous study of chemical abundances of
refractory elements in 101 stars with and 94 without known planetary
companions. We carry out an in-depth investigation of the abundances of Si,
Ca,
Sc, Ti, V, Cr, Mn, Co, Ni, Na, Mg and Al. The new comparison sample,
spanning
the metallicity range -0.70< [Fe/H]< 0.50, fills the gap that previously
existed, mainly at high metallicities, in the number of stars without known
planets. We used an enlarged set of data including new observations,
especially
for the field ``single'' comparison stars. The line list previously studied
by
other authors was improved: on average we analysed 90 spectral lines in
every
spectrum and carefully measured more than 16600 equivalent widths (EW) to
calculate the abundances. We investigate possible differences between the
chemical abundances of the two groups of stars, both with and without
planets.
The results are globally comparable to those obtained by other authors, and
in
most cases the abundance trends of planet-host stars are very similar to
those
of the comparison sample. This work represents a step towards the
comprehension
of recently discovered planetary systems. These results could also be useful
for verifying galactic models at high metallicities and consequently improve
our knowledge of stellar nucleosynthesis and galactic chemical evolution.

\\ ( http://arXiv.org/abs/astro-ph/0512219> , 210kb)

Paper: astro-ph/0512221
Date: Thu, 8 Dec 2005 15:11:22 GMT (163kb)

Title: Abundance ratios of volatile vs. refractory elements in
planet-harbouring stars: hints of pollution?

Authors: A. Ecuvillon (1), G. Israelian (1), N. C. Santos (2,3), M. Mayor
(3),
G. Gilli (1,4) ((1) IAC, Spain, (2) Observatorio Astronomico de Lisboa,
Portugal, (3) Observatoire de Geneve, Switzerland, (4) Dipartimento di
Astronomia, Universita di Padova, Italy)

Comments: 10 pages, 7 figures, accepted for publication in A&A. Figures with
higher resolution are available at www.iac.es/proyect/abuntest<http://www.iac.es/proyect/abuntest>
\\
We present the [X/H] trends as function of the elemental condensation
temperature Tc in 88 planet host stars and in a volume-limited comparison
sample of 33 dwarfs without detected planetary companions. We gathered
homogeneous abundance results for many volatile and refractory elements
spanning a wide range of Tc, from a few dozens to several hundreds kelvin.
We
investigate possible anomalous trends of planet hosts with respect to
comparison sample stars in order to detect evidence of possible pollution
events. No significant differences are found in the behaviour of stars with
and
without planets. This result is in agreement with a ``primordial'' origin of
the metal excess in planet host stars. However, a subgroup of 5 planet host
and
1 comparison sample stars stands out for having particularly high [X/H] vs.
Tc
slopes.

\\ ( http://arXiv.org/abs/astro-ph/0512221> , 163kb)

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\\
Paper: astro-ph/0512222
Date: Thu, 8 Dec 2005 15:16:52 GMT (42kb)

Title: Condensation temperature trends among stars with planets

Authors: Guillermo Gonzalez

Comments: 5 pages, 7 figures, MNRAS Letter in press
\\
Results from detailed spectroscopic analyses of stars hosting massive
planets
are employed to search for trends between abundances and condensation
temperatures. The elements C, S, Na, Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Ni
and
Zn are included in the analysis of 64 stars with planets and 33 comparison
stars. No significant trends are evident in the data. This null result
suggests
that accretion of rocky material onto the photospheres of stars with planets
is
not the primary explanation for their high metallicities. However, the
differences between the solar photospheric and meteoritic abundances do
display
a weak but significant trend with condensation temperature. This suggests
that
the metallicity of the sun's envelope has been enriched relative to its
interior by about 0.07 dex.

\\ ( http://arXiv.org/abs/astro-ph/0512222> , 42kb)

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