A Possible Correlation between Mass Ratio and Period Ratio in Multiple Planetary Systems

We report on a possible correlation between the mass ratio and period ratio of pairs of adjacent planets in extra-solar planetary systems. Monte-Carlo simulations show that the effect is significant to level of 0.7%, as long as we exclude two pairs of planets whose periods are at the 1:2 resonance. Only the next few multiple systems can tell if the correlation is real.Comment: 8 pages, 2 figures, published in The Astrophysical Journal Letter

Cross-Correlation and Maximum Likelihood Analysis: A New Approach to Combine Cross-Correlation Functions

This paper presents a new approach to combine cross-correlation functions. The combination is based on a maximum-likelihood approach and uses a non-linear combination scheme. It can be effective for radial-velocity analysis of multi-order spectra, or for analysis of multiple exposures of the same object. Simulations are presented to show the potential of the suggested combination scheme. The technique has already been used to detect a very faint companion of HD41004.Comment: 6 pages, 7 figures, accepted for publication in MNRA