The High Eccentricity of the Planet Around 16 Cyg B

We consider the high eccentricity, 0.66, of the newly discovered planet around 16 Cyg B, using the fact that the parent star is part of a wide binary. We show that the high eccentricity of the planet could be the result of tidal forces exerted on 16 Cyg B and its planet by 16 Cyg A, the distant companion in the system. By following stellar triple systems with parameters similar to those of 16 Cyg, we have established that the orbital eccentricity of the planet could have gone through strong modulation, with an amplitude of 0.8 or even larger, with typical timescale of tens of millions years. The amplitude of the planet eccentricity strongly depends on the relative inclination between the plane of motion of the planet and that of the wide binary 16 Cyg AB. To account for the present eccentricity of the planet we have to assume that the angle between the two planes of motion is large, at least 60 deg. We argue that this assumption is reasonable for wide binaries like 16 Cyg AB.Comment: 2 Figures, Latex, submitted for publication to ApJ

Improved equations for eccentricity generation in hierarchical triple systems

In a series of papers, we developed a technique for estimating the inner eccentricity in hierarchical triple systems, with the inner orbit being initially circular. However, for certain combinations of the masses and the orbital elements, the secular part of the solution failed. In the present paper, we derive a new solution for the secular part of the inner eccentricity, which corrects the previous weakness. The derivation applies to hierarchical triple systems with coplanar and initially circular orbits. The new formula is tested numerically by integrating the full equations of motion for systems with mass ratios from 10^(-3) to 10^(3). We also present more numerical results for short term eccentricity evolution, in order to get a better picture of the behaviour of the inner eccentricity.Comment: Accepted for publication in MNRA

Dynamical analysis and constraints for the HD 196885 system

The HD\,196885 system is composed of a binary star and a planet orbiting the primary. The orbit of the binary is fully constrained by astrometry, but for the planet the inclination with respect to the plane of the sky and the longitude of the node are unknown. Here we perform a full analysis of the HD\,196885 system by exploring the two free parameters of the planet and choosing different sets of angular variables. We find that the most likely configurations for the planet is either nearly coplanar orbits (prograde and retrograde), or highly inclined orbits near the Lidov-Kozai equilibrium points, i = 44^{\circ} or i = 137^{\circ} . Among coplanar orbits, the retrograde ones appear to be less chaotic, while for the orbits near the Lidov-Kozai equilibria, those around \omega= 270^{\circ} are more reliable, where \omega_k is the argument of pericenter of the planet's orbit with respect to the binary's orbit. From the observer's point of view (plane of the sky) stable areas are restricted to (I1, \Omega_1) \sim (65^{\circ}, 80^{\circ}), (65^{\circ},260^{\circ}), (115^{\circ},80^{\circ}), and (115^{\circ},260^{\circ}), where I1 is the inclination of the planet and \Omega_1 is the longitude of ascending node.Comment: 10 pages, 7 figures. A&A Accepte

Observational Evidence for Tidal Interaction in Close Binary Systems

This paper reviews the rich corpus of observational evidence for tidal effects in short-period binaries. We review the evidence for ellipsoidal variability and for the observational manifestation of apsidal motion in eclipsing binaries. Among the long-term effects, circularization was studied the most, and a transition period between circular and eccentric orbits has been derived for eight coeval samples of binaries. As binaries are supposed to reach synchronization before circularization, one can expect finding eccentric binaries in pseudo-synchronization state, the evidence for which is reviewed. The paper reviews the Rossiter-McLaughlin effect and its potential to study spin-orbit alignment. We discuss the tidal interaction in close binaries that are orbited by a third distant companion, and review the effect of pumping the binary eccentricity by the third star. We then discuss the idea that the tidal interaction induced by the eccentricity modulation can shrink the binary separation. The paper discusses the extrasolar planets and the observational evidence for tidal interaction with their parent stars which can induce radial drift of short-period planets and circularization of planetary orbits. The paper reviews the revolution of the study of binaries that is currently taking place, driven by large-scaled photometric surveys that are detecting many thousands of new binaries and tens of extrasolar planets. In particular, we review several studies that have been used already thousands of lightcurves of eclipsing binaries to study tidal circularization of early-type stars in the LMC.Comment: 67 pages. Review Paper. To appear in "Tidal effects in stars, planets and disks", M.-J. Goupil and J.-P. Zahn (eds.), EAS Publications Serie

Distinguishing Easy and Hard Instances

Error analysis is a key step in developing statistical parsers. In doing this, we manually discover typical cases by examining parser output. In this paper we argue that the process can be speeded up by considering the output from an ensemble of parsers. We do this by resampling small proportions (10% and up) from the training data, and exploiting the high diversity of the resulting parsers - resulting from the sparseness of natural-language data. Varying the sample size, we can trace the gradual learning of each instance and classify instances into a few types. This division helps in distinguishing instances which are hard for the system, from instances which may be learned in principle. We suggest that such analysis can yield a qualitative approach to evaluation of statistical parsers

BioCreative Task 2.1: The Edinburgh-Stanford system

We describe a system for BioCreative Task 2.1: finding evidence that suppports a GO term annotation for a given protein in a given biomedical paper. We approach the problem as a question answering task, where the query is constructed from a protein name, a GO term and its definition

Incorporating Compositional Evidence in Memory-Based Partial Parsing

In this paper, a memory-based parsing method is extended for handling compositional structures. The method is oriented for learning to parse any selected subset of target syntactic structures. It is local, yet can handle also compositional structures

On the Robustness of Entropy-Based Similarity Measures in Evaluation of Subcategorization Acquisition Systems

Some statistical learning systems are evaluated using measures of distributional similarity. To deal with the problem of zero events in the distributions under comparison, smoothing is frequently performed before similarity measures are applied. Smoothing alters the information in the original distribution, and may add noise to the results. Here, we investigate the sensitivity of entropy-based similarity measures to noise from uninformative smoothing. Our experiments with two subcategorization acquisition systems show that similarity measures vary in their robustness. While some are led astray by noise from smoothing, others are more resilient