EAS Publications Series
Volume 42, 2010Extrasolar Planets in Multi-Body Systems: Theory and Observations
|Page(s)||169 - 173|
|Published online||19 April 2010|
K. Goździewski, A. Niedzielski and J. Schneider (eds)
EAS Publications Series, 42 (2010) 169-173
Observational biases in determining extrasolar planet eccentricities
School of Natural Sciences, Institute for Advanced Study, Princeton, NJ 08540, USA
2 Department of Astronomy, University of Florida, Gainsville, FL 32611-2055, USA
We investigate biases in the measurement of exoplanet orbital parameters – especially eccentricity – from radial velocity (RV) observations. In this contribution we consider single-planet systems. We create a mock catalog of RV data, choosing planet masses and orbital periods, and observing patterns to mimic those of actual RV surveys. Using Markov chain Monte Carlo (MCMC) simulations, we generate a posterior sample for each mock data set, calculate best-fit orbital parameters for each data set, and compare these to the true values. We find that the precision of our derived eccentricities is most closely related to the effective signal-to-noise ratio, K√N/σ, where K is the velocity amplitude, σ is the effective single-measurement precision, and N is the number of observations. We also find that eccentricities of planets on nearly circular (e<0.05) orbits are preferentially overestimated. While the Butler et al. (2006) catalog reports e<0.05 for just 20% of its planets, we estimate that the true fraction of e<0.05 orbits is about 50%. We investigate the accuracy, precision, and bias of alternative sets of summary statistics and find that the median values of h = esinω and k = ecosω (where ω is the longitude of periapse) of the posterior sample typically provide more accurate, more precise, and less biased estimates of eccentricity than traditional measures.
© EAS, EDP Sciences, 2010
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.