Paper: astro-ph/0511295
Date: Thu, 10 Nov 2005 12:43:49 GMT (411kb)

Title: About putative Neptune-like extrasolar planetary candidates

Authors: Krzysztof Gozdziewski & Cezary Migaszewski

Comments: Contains 14 pages, 24 figures, 1 table. Accepted for publication in
Astronomy and Astrophysics (4/11/2005). This is a raw unedited manuscript.
Some figures are in low-resolution format suitable for publication in
astro-ph
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We re-analyze the precision radial velocity (RV) data of HD188015, HD114729,
HD190360, HD147513 and HD208487. All these stars are supposed to host Jovian
companions in long-period orbits. We test a hypothesis that the residuals of
the 1-planet model of the RV or an irregular scatter of the measurements about
the synthetic RV curve may be explained by the existence of additional planets
in short-period orbits. We perform a global search for the best fits in the
orbital parameters space with genetic algorithms and simplex method. This makes
it possible to verify and extend the results obtained with an application of
commonly used FFT-based periodogram analysis for identifying the leading
periods. Our analysis confirms the presence of a periodic component in the RV
data of HD190360 which may correspond to a hot-Neptune planet. We found four
new cases when the 2-planet model yields significantly better fits to the RV
data than the best 1-planet solutions. If the periodic variability of the
residuals of single-planet fits has indeed a planetary origin then hot-Neptune
planets may exist in these extrasolar systems. We estimate their orbital
periods in the range of 7-20d and minimal masses about of 20 masses od the
Earth.

\\ ( http://arXiv.org/abs/astro-ph/0511295 , 411kb)