Hill stability cannot be easily established in the classical 3-body problem with point masses, as sufficient energy for escape of one of the bodies can always be extracted from the gravitational potential energy. For the finite density, so-called Full 3-body problem the lower limits on the gravitational potential energy ensure that Hill stability can exist. For the equal mass Full 3-body problem this can be easily established, with the result that for any equal mass, finite density 3-body problem in or near a contact equilibrium, none of the components of the system can escape in the ensuing motion.

We have studied turbulent plasma as a complex system applying the method known as Horizontal Visibility Graph (HVG) to obtain the Kullback-Leibler Divergence (KLD) as a first approach to characterize the reversibility of the time series of the magnetic fluctuations. For this, we have developed the method on Particle In Cell (PIC) simulations for a magnetized plasma and on solar wind magnetic time series, considering slow and fast wind. Our numerical results show that low irreversibility values are verified for magnetic field time series associated with Maxwellian distributions. In addition, considering the solar wind plasma, our preliminary results seem to indicate that greater irreversibility degrees are reached by the magnetic field associated with slow solar wind.

If it is commonly agreed that the presence of a (moderately) close stellar companion affects the formation and the dynamical evolution of giant planets, the frequency of giant planets residing in binary systems separated by less than 100 AU is unknown. To address this issue, we have conducted with VLT/NACO a systematic adaptive optics search for moderately close stellar companions to 130 nearby solar-type stars. According to the data from Doppler surveys, half of our targets host at least one planetary companion, while the other half show no evidence for short-period giant planets. We present here the final results of our survey, which include a new series of second-epoch measurements to test for common proper motion. The new observations confirm the physical association of two companion candidates and prove the unbound status of many others. These results strengthen our former conclusion that circumstellar giant planets are slightly less frequent in binaries with mean semimajor axes between 35 and 100 AU than in wider systems or around single stars.

Over the last fifty years since the discovery of pulsars, our understanding of where and how pulsars emit the radiation we observe has undergone significant revision. The location and mechanisms of high-energy radiation are intimately tied to the sites of particle acceleration. The evolution of emission models has paralleled the development of increasingly more sensitive telescopes, especially at high energies. I will review the history of pulsar emission modeling, from the early days of gaps at the polar caps, to outer gaps and slot gaps in the outer magnetosphere, to the present era of global magnetosphere simulations that locate most acceleration and high-energy emission in the current sheets.

Motivated by the increasing need for observational resources for the study of time varying astronomy, the Las Cumbres Observatory Global Telescope (LCOGT) is a private foundation, whose goal is to build a global network of robotic telescopes for scientific research and education. Once completed, the network will become a unique tool, capable of continuous monitoring from both the Northern and Southern Hemispheres. The network currently includes 2 × 2.0 m telescopes, already making an impact in the field of exoplanet research. In the next few years they will be joined by at least 12 × 1.0 m and 20 × 0.4 m telescopes. The increasing amount of LCOGT observational resources in the coming years will be of great service to the astronomical community in general, and the exoplanet community in particular.

We report on recent developments in the study of diffuse interstellar bands in the Local Group galaxies. We present preliminary results on the detection of the 5780 Å DIB toward 17 targets in the vicinity of NGC 206 in M31.

The Pan-STARRS pathfinding telescope PS1 will begin a major set of surveys starting in 2008, and lasting for 3.5 years. One of these, the PS1 3π Survey, will repeatedly observe the entire sky north of −30 degrees, visiting every position 12 times in each of 5 filters. With single-epoch astrometry of 10 milliarcseconds, these observations will yield parallaxes for stars within 100 pc and proper motions out to several hundred pc. The result will be an unprecedented view on nearby stellar populations and insight into the dynamical structure of the local portions of the Galaxy. One exciting science product will be a volume-limited sample of nearby low-mass objects including thousands of L dwarfs, hundreds of T dwarfs, and perhaps even cooler sub-stellar objects. Another project will use proper-motion measurements to improve the membership of nearby star forming regions.

Since the discovery of its transiting nature, the super-Earth 55 Cnc e has become one of the most enthusiastically studied exoplanets, having been observed spectroscopically and photometrically, in the ultraviolet, optical and infrared regimes. To this rapidly growing data set, we contribute 42 days of new, nearly continuous MOST photometry of the 55 Cnc system. Our analysis of these observations together with the discovery photometry obtained in 2011 allows us to determine the planetary radius (1.990+0.084−0.080) and orbital period (0.7365417+0.0000025−0.0000028) of 55 Cnc e with unprecedented precision. We also followed up on the out-of-transit phase variation first observed in the 2011 photometry, and set an upper limit on the depth of the planet's secondary eclipse, leading to an upper limit on its geometric albedo of 0.6.

Atomic diffusion may play a significant role for the Sun and Population I Main Sequence stars up to some 25000 K, Population II turnoff stars and cluster age determinations, horizontal branch stars (including sdOs and sdBs), white dwarfs and neutron stars. In all these cases, radiative accelerations play a significant role. A stars are, however, arguably those that show most prominently the effects of atomic diffusion. In so far as the effects of accretion, mass loss, turbulence and meridional circulation may be neglected in the evolutionary models of A stars, the effects of atomic diffusion in them have now been calculated from first principles and are presented using complete evolutionary models of 1.7 and 2.5 $M_{\odot}$ stars. Their abundance anomalies are not only superficial, but extend over a significant fraction of the stellar radius. Iron convection zones appear at a temperature of about 200000 K. Abundance anomalies similar to those observed in Am stars are produced. However the comparison with the observations requires linking atmospheres to interior evolution. Models that have been proposed to take into account atomic diffusion in atmospheric regions to explain observations are critically reviewed. They depend on a number of parameters. Unfortunately the atmospheric regions are imperfectly modeled, the magnetic field is not taken into account, and important hydrodynamic processes currently require arbitrary parameters for their description.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

New constraints on stellar models are provided by large surveys of massive stars, interferometric observations and asteroseismology. After a review of the main results so far obtained, we present new results from rotating models and discuss comparisons with observed features. We conclude that rotation is a key feature of massive star physics.

The combination of the collecting power of an ELT with an ultra-stable high resolution spectrograph opens up the possibility to measure for the first time directly the dynamical effect of the acceleration of the Universe. CODEX will also provide unique opportunities for advance in many other branches of astrophysics. The CODEX design is based on an array of several identical spectrographs. It is highly modular and can be easily adapted to a large range of sky apertures and telescope diameters. CODEX is designed to work as a seeing limited instrument. The requirements for the telescope are moderate and clearly identified.

In this paper we present the results of our new classification of asteroid families, upgraded by using catalog with > 500,000 asteroids. We discuss the outcome of the most recent update of the family list and of their membership. We found enough evidence to perform 9 mergers of the previously independent families. By introducing an improved method of estimation of the expected family growth in the less populous regions (e.g. at high inclination) we were able to reliably decide on rejection of one tiny group as a probable statistical fluke. Thus we reduced our current list to 115 families. We also present newly determined ages for 6 families, including complex 135 and 221, improving also our understanding of the dynamical vs. collisional families relationship. We conclude with some recommendations for the future work and for the family name problem.

The idea that the Solar System possesses a primordial isotropic cloud of comets has been with us in quantitative form for about thirty years (Oort 1950). A considerable edifice has been built on this proposition (e.g. Weissmann 1982), which has proved durable despite indications that the cloud may in fact be significantly non-thermal and display Galactic alignments (Tyror 1957, Richter 1963, Oja 1975, Yabushita et al. 1979, Radzievsky 1981). However with the discovery in recent years of a system of massive molecular clouds in the Galactic disc, it has become apparent that the environment in which the Oort cloud has to survive is very different from that envisaged in 1950; a re-appraisal of the standard picture is therefore called for.

One corollary of the discovery of the molecular clouds is that the traditional objections to an interstellar comet cosmogony, such as the lack of observed hyperbolic comets and the difficulty of growing and capturing them, may no longer apply (see for example the recent review by Clube & Napier 1982a, hereinafter CN). Another consequence, reviewed here, is that tidal effects due to molecular clouds may be so large that the Oort cloud is frequently disrupted (CN; Napier & Staniucha 1982). In this situation frequent replenishment is implied and it is therefore necessary to discriminate between the primordial and the observed Oort cloud and to consider possible alternative sources for the latter. Such an enquiry would provide constraints on the as yet unsolved problem of comet formation.

We present the results of a study performed with the goal to investigate whether low-mass pre-main sequence binary stars are formed by multiple fragmentation or via stellar capture. If binaries form preferentially by fragmentation, we expect their disks to be co-planar. On the other hand, the capture scenario will lead to a random distribution of disk orientations. We performed near-infrared polarization measurements of 49 young visual binary stars in the K band with SOFI at the NTT. The near-infrared excess radiation of the targets mostly point to the presence of disks. For a major fraction of the sample, evidence for disks is also obvious from other features (outflows, jets, Herbig-Haro objects). We derived the disk orientation from the orientation of the polarization vector of both components of each binary. This statistical study allows to test which hypothesis (co-planarity, random orientation) is consistent with the observed distribution of polarimetric position angles. We find evidence that the disks are preferentially aligned.

The largest magnetic field encountered in the observable Universe can be found in neutron stars, in particular in radio pulsars and magnetars. While recent discoveries have slowly started to blur the distinction between these two classes of highly magnetized neutron stars, it is possible that both types of sources are linked via an evolutionary sequence. Indications for this to be the case are obtained from observations of the spin-evolution of pulsars. It is found that most young pulsars are heading across the top of the main distribution of radio pulsars in the P–Ṗ-diagram, suggesting that at least a sub-class of young pulsars may evolve into objects with magnetar-like magnetic field strengths. Part of this evolutionary sequence could be represented by RRATs which appear to share at least in parts properties with both pulsars and magnetars.

Infrared molecular spectroscopy is a key tool for the observation of gas in the innermost region of disks around T Tauri stars. In this contribution, we examine how infrared spectroscopy of CO can be used to study the inner truncation region of disks around T Tauri stars. The inferred inner gas radii for T Tauri star disks are compared to the inner dust radii of disks, to the expectations of models for disk truncation, and to the orbital distribution of short-period extra-solar planets.

Jets from radio galaxies can have dramatic effects on the medium through which they propagate. We review observational evidence for jet-induced star formation in low (‘FR-I’) and high (‘FR-II’) luminosity radio galaxies, at low and high redshifts respectively. We then discuss numerical simulations which are aimed to explain a jet-induced starburst (‘Minkowski's Object’) in the nearby FR-I type radio galaxy NGC 541. We conclude that jets can induce star formation in moderately dense (10 cm−3), warm (104 K) gas; that this may be more common in the dense environments of forming, active galaxies; and that this may provide a mechanism for ‘positive’ feedback from AGN in the galaxy formation process.

Traditional photoelectric techniques can achieve millimagnitude precision if a few simple rules are scrupulously followed. We illustrate the practical limits of differential photometry obtained with a dedicated telescope and photometer. Using a highly homogeneous set of measurements of bright F, G, and K solar analog stars, we present the distribution of observational noise and intrinsic stellar variability over a typical observing season and over the entire 8-year program. Finally, we list Strömgren uvby standards which we found to vary slightly.

Over the past decade a comprehensive, semiquantitative theoretical scenario for the final evolutionary stages of low and intermediate mass stars has been progressively elaborated and refined. It concerns the envelope ejection terminating the Asymptotic Giant Branch (AGB) phase, the AGB to Planetary Nebula (PN) transition, the fading and possible rejuvenation of PN nuclei, the formation processes of hydrogen-deficient stars, and the final production of white dwarfs (WD) of the DA and non-DA varieties (Renzini 1979, 1981a, 1981b, 1982, 1983, Iben & Renzini 1983, Iben et al. 1983, Iben 1984, 1985, 1987, Iben & Tutukov 1984, Iben & MacDonald 1985, 1986). In developing this scenario several important results of stellar evolution and hydrodynamical calculations have been incorporated, including in particular those of Paczynski (1971), Wood (1974), Härm & Schwarzschild (1975), Schönberner (1979, 1983), and Tuchman, Sack & Barkat (1979).