As the quality and quantity of astrophysical data continue to improve, the precision with which certain astrophysical events can be timed becomes limited not by the data themselves, but by the manner, standard, and uniformity with which time itself is referenced. While some areas of astronomy (most notably pulsar studies) have required absolute time stamps with precisions of considerably better than 1 minute for many decades, recently new areas have crossed into this regime. In particular, in the exoplanet community, we have found that the (typically unspecified) time standards adopted by various groups can differ by as much as a minute. Left uncorrected, this ambiguity may be mistaken for transit timing variations and bias eccentricity measurements. We argue that, since the commonly-used Julian Date, as well as its heliocentric and barycentric counterparts, can be specified in several time standards, it is imperative that their time standards always be reported when accuracies of 1 minute are required. We summarize the rationale behind our recommendation to quote the site arrival time, in addition to using BJD, the Barycentric Julian Date in the Barycentric Dynamical Time standard for any astrophysical event. The BJD is the most practical absolute time stamp for extraterrestrial phenomena, and is ultimately limited by the properties of the target system. We compile a general summary of factors that must be considered in order to achieve timing precisions ranging from 15 minutes to 1 µs. Finally, we provide software tools that, in principal, allow one to calculate BJD to a precision of 1 µs for any target from anywhere on Earth or from any spacecraft.

Aims: We present a new method that allows identifying the onset of orbital instability, as well as quasi-periodicity and multi-periodicity, for planets in binary systems. This method is given for the special case of the circular restricted 3-body problem (CR3BP). Methods: Our method relies on an approach given by differential geometry that analyzes the curvature of the planetary orbit in the synodic coordinate system. The centerpiece of the method consists in inspecting the effective (instantaneous) eccentricity of the orbit based on the hodograph in rotated coordinates and in calculating the mean and median values of the eccentricity distribution. Results: Orbital stability and instability can be mapped by numerically inspecting the hodograph and/or the effective eccentricity of the orbit in the synodic coordinate system. The behavior of the system depends solely on the mass ratio μ of the binary components and the initial distance ratio ρ0 of the planet relative to the stellar separation distance noting that the stellar components move on circular orbits. Our study indicates that orbital instability occurs when the median of the effective eccentricity distribution exceeds unity. This instability criterion can be compared to other criteria, including those based on Jacobi's integral and the zero-velocity contour of the planetary orbit. Conclusions: The method can be used during detailed numerical simulations and in contrast to other methods such as methods based on the Lyapunov exponent does not require a piece-wise secondary integration of the planetary orbit. Although the method has been deduced for the CR3BP, it is likely that it can be expanded to more general cases.

The van Dam-Veltman-Zakharov (vDVZ) discontinuity requires that the mass m of the graviton is exactly zero, otherwise measurements of the deflection of starlight by the Sun and the precession of Mercury’s perihelion would conflict with their theoretical values. This theoretical discontinuity is open to question for numerous reasons. In this paper we show from a phenomenological viewpoint that the m>0 hypothesis is in accord with Supernova Ia and CMB observations, and that the large scale structure of the universe suggests that m~10-30eV/c2.

This is a tutorial presentation of special features of galactic disc dynamics, which completes our introduction to galactic dynamics initially presented in [30]. The emphasis is on topics where galactic dynamics and celestial mechanics share common starting points and/or methods of approach. We start by giving some definitions and general notions on the link between observations and dynamical modeling of discs. Then we focus on the application of resonant Hamiltonian perturbation theory in disc resonances. By examining in detail the case of the Inner Lindblad resonance, we demonstrate how resonant perturbation theory leads to an orbital theory of spiral structure in normal galaxies. Passing to barred galaxies, the phase space structure and the role of chaos in the corotation region are analyzed. This is accomplished by a summary of the modern theory of invariant manifolds of unstable periodic orbits in the vicinity of L1 or L2, which can interpret the generation of spiral patterns by chaotic orbits beyond corotation. Some additional topics, potentially important for disc dynamics, are briefly commented.

(Eibe) We present the first results from long-term photometric observations carried out with the INTA-CAB 50-cm telescope in a fully robotic mode. The data belong to an ongoing programme for the photometric follow up of known transiting close-in giant planets. We describe the techniques used to generate differential light curves of the programme stars and discuss the photometric performance obtained over the first year of operation.

We present the first far-IR observations of the solar-type stars δ Pav, HR 8501, 51 Peg and ζ2 Ret, taken within the context of the DUNES Herschel open time key programme (OTKP). This project uses the PACS and SPIRE instruments with the objective of studying infrared excesses due to exo-Kuiper belts around nearby solar-type stars. The observed 100 μm fluxes from δ Pav, HR 8501, and 51 Peg agree with the predicted photospheric fluxes, excluding debris disks brighter than Ldust/Lstar 5 × 10-7 (1σ level) around those stars. A flattened, disk-like structure with a semi-major axis of 100 AU in size is detected around ζ2 Ret. The resolved structure suggests the presence of an eccentric dust ring, which we interpret as an exo-Kuiper belt with Ldust/Lstar ≈ 10-5.

Context: To determine the physical parameters of a transiting planet and its host star from photometric and spectroscopic analysis, it is essential to independently measure the stellar mass. This is often achieved by the use of evolutionary tracks and isochrones, but the mass result is only as reliable as the models used.
Aims: The recent paper by Torres et al. (2010, A&ARv, 18, 67) showed that accurate values for stellar masses and radii could be obtained from a calibration using Teff, log g and [Fe/H]. We investigate whether a similarly good calibration can be obtained by substituting log ρ- the fundamental parameter measured for the host star of a transiting planet - for log g, and apply this to star-exoplanet systems.
Methods: We perform a polynomial fit to stellar binary data provided in Torres et al. (2010) to obtain the stellar mass and radius as functions of Teff, log g and [Fe/H], with uncertainties on the fit produced from a Monte Carlo analysis. We apply the resulting equations to measurements for seventeen SuperWASP host stars, and also demonstrate the application of the calibration in a Markov Chain Monte Carlo analysis to obtain accurate system parameters where spectroscopic estimates of effective stellar temperature and metallicity are available.
Results: We show that the calibration using log ρ produces accurate values for the stellar masses and radii; we obtain masses and radii of the SuperWASP stars in good agreement with isochrone analysis results. We ascertain that the mass calibration is robust against uncertainties resulting from poor photometry, although a good estimate of stellar radius requires good-quality transit light curve to determine the duration of ingress and egress.

A new simulation tool is introduced for extracting Earth conductivity information from geomagnetic satellites in low Earth orbit (LEO) such as CHAMP, Swarm and potential follow-on missions. Theoretical reconstruction of spherical harmonic spectra of global universal time (UT) geomagnetic field maps is analysed. An idealized regular solar daily variation field is assumed, along with its induced counterpart from a radially stratified Earth. Solar-quiet (Sq) spectra can be reliably reconstructed from discrete time-series of measurements sampled daily within a fixed UT window. A single LEO satellite should be in orbit for at least 1 yr under quiet-time conditions to ensure accurate spectral reconstruction of an Sq geomagnetic spectrum. The length of the daily sampling window and random day-to-day variability in the Sq source strength have only minor effects on spectral reconstruction. The shape of the spectra, and spectral ratios, are independent of radial mantle conductivity. Further research employing 3-D forward modelling of induction in a laterally heterogeneous earth, with more realistic and complete external source descriptions, is advocated. The new simulation tool should prove valuable to planners of future multisatellite geomagnetic missions, as well as scientists interested in analysing and interpreting satellite induction signals.

A new era of directly imaged extrasolar planets has produced a three-planet system, where the masses of the planets have been estimated by untested cooling models. We point out that the nominal circular, face-on orbits of the planets lead to a dynamical instability in ~105 yr, a factor of at least 100 shorter than the estimated age of the star. Reduced planetary masses produce stability only for unreasonably small planets (<~ MJup). Relaxing the face-on assumption, but still requiring circular orbits while fitting the observed positions, makes the instability time even shorter. A promising solution is that the inner two planets have a 2:1 commensurability between their periods, and they avoid close encounters with each other through this resonance. The fact that the inner resonance has lasted until now, in spite of the perturbations of the outer planet, leads to a limit lsim10 MJup on the masses unless the outer two planets are also engaged in a 2:1 mean-motion resonance. In a double resonance, which is consistent with the current data, the system could survive until now even if the planets have masses of ~20 MJup. Apsidal alignment can further enhance the stability of a mean-motion resonant system. A completely different dynamical configuration, with large eccentricities and large mutual inclinations among the planets, is possible but finely tuned.

The Lidov-Kozai mechanism allows a body to periodically exchange its eccentricity with inclination. It was first discussed in the framework of the quadrupolar secular restricted three-body problem, where the massless particle is the inner body, and later extended to the quadrupolar secular non-restricted three-body problem. In this paper, we propose a different point of view on the problem by looking first at the restricted problem where the massless particle is the outer body. In this situation, equilibria at high mutual inclination appear, which corresponds to the population of stable particles that Verrier & Evans find in stable, high-inclination circumbinary orbits around one of the components of the quadruple star HD 98800. We provide a simple analytical framework using a vectorial formalism for these situations. We also look at the evolution of these high-inclination equilibria in the non-restricted case.

ABSTRACT HD189733 is a K2 dwarf, orbited by a giant planet at 8.8 stellar radii. In order to study magnetospheric interactions between the star and the planet, we explore the large-scale magnetic field and activity of the host star. We collected spectra using the ESPaDOnS and the NARVAL spectropolarimeters, installed at the 3.6-m Canada-France-Hawaii telescope and the 2-m Telescope Bernard Lyot at Pic du Midi, during two monitoring campaigns (2007 June and 2008 July). HD189733 has a mainly toroidal surface magnetic field, having a strength that reaches up to 40G. The star is differentially rotating, with latitudinal angular velocity shear of dΩ= 0.146 +/- 0.049radd-1, corresponding to equatorial and polar periods of 11.94 +/- 0.16d and 16.53 +/- 2.43d, respectively. The study of the stellar activity shows that it is modulated mainly by the stellar rotation (rather than by the orbital period or the beat period between the stellar rotation and the orbital periods). We report no clear evidence of magnetospheric interactions between the star and the planet. We also extrapolated the field in the stellar corona and calculated the planetary radio emission expected for HD189733b, given the reconstructed field topology. The radio flux we predict in the framework of this model is time variable and potentially detectable with LOFAR.

The European Pulsar Timing Array (EPTA) is a multi-institutional, multi-telescope collaboration, with the goal of using high-precision pulsar timing to directly detect gravitational waves. In this paper we discuss the EPTA member telescopes, current achieved timing precision and near-future goals. We report a preliminary upper limit to the amplitude of a gravitational wave background. We also discuss the Large European Array for Pulsars, in which the five major European telescopes involved in pulsar timing will be combined to provide a coherent array that will give similar sensitivity to the Arecibo radio telescope, and larger sky coverage.

The importance of an accurate model of the Moon gravity field has been assessed for future navigation missions orbiting and/or landing on the Moon, in order to use our natural satellite as an intermediate base for next solar system observations and exploration as well as for lunar resources mapping and exploitation. One of the main scientific goals of MAGIA mission, whose Phase A study has been recently funded by the Italian Space Agency (ASI), is the mapping of lunar gravitational anomalies, and in particular those on the hidden side of the Moon, with an accuracy of 1 mGal RMS at lunar surface in the global solution of the gravitational field up to degree and order 80. MAGIA gravimetric experiment is performed into two phases: the first one, along which the main satellite shall perform remote sensing of the Moon surface, foresees the use of Precise Orbit Determination (POD) data available from ground tracking of the main satellite for the determination of the long wavelength components of gravitational field. Improvement in the accuracy of POD results are expected by the use of ISA, the Italian accelerometer on board the main satellite. Additional gravitational data from recent missions, like Kaguya/Selene, could be used in order to enhance the accuracy of such results. In the second phase the medium/short wavelength components of gravitational field shall be obtained through a low-to-low (GRACE-like) Satellite-to-Satellite Tracking (SST) experiment. POD data shall be acquired during the whole mission duration, while the SST data shall be available after the remote sensing phase, when the sub-satellite shall be released from the main one and both satellites shall be left in a free-fall dynamics in the gravity field of the Moon. SST range-rate data between the two satellites shall be measured through an inter-satellite link with accuracy compliant with current state of art space qualified technology. SST processing and gravitational anomalies retrieval shall benefit from a second ISA accelerometer on the sub-satellite in order to decouple lunar gravitational signal from other accelerations. Experiment performance analysis shows that the stated scientific requirements can be achieved with a low mass and low cost sub-satellite, with a SST gravimetric mission of just few months.

For rigid bodies close to a sphere, we propose an analytical solution that is free from elliptic integrals and functions, and can be fundamental for application to perturbed problems. After reordering the Hamiltonian as a perturbed spherical rotor, the Lie-series solution is generated up to an arbitrary order. Using the inertia parameters of different solar system bodies, the comparison of the approximate series solution with the exact analytical one shows that the precision reached with relatively low orders is at the same level of the observational accuracy for the Earth and Mars. Thus, for instance, the periodic errors of the mathematical solution are confined to the microarcsecond level with a simple second-order truncation for the Earth. On the contrary, higher orders are required for the mathematical solution to reach a precision at the expected level of accuracy of proposed new theories for the rotational dynamics of the Moon.

The Mid-Pleistocene transition (MPT) was the time when quasi-periodic (˜ 100 kyr), high-amplitude glacial variability developed in the absence of any significant change in the character of orbital forcing, leading to the establishment of the characteristic pattern of late Pleistocene climate variability. It has long been known that the interval around 900 ka stands out as a critical point of the MPT, when major glaciations started occurring most notably in the northern hemisphere. Here we examine the record of climatic conditions during this significant interval, using high-resolution stable isotope records from benthic and planktonic foraminifera from a sediment core in the North Atlantic (Integrated Ocean Drilling Program Expedition 306, Site U1313). We have considered the time interval from late in Marine Isotope Stage (MIS) 23 to MIS 20 (910 to 790 ka). Our data indicate that interglacial MIS 21 was a climatically unstable period and was broken into four interstadial periods, which have been identified and correlated across the North Atlantic region. These extra peaks tend to contradict previous studies that interpreted the MIS 21 variability as consisting essentially of a linear response to cyclical changes in orbital parameters. Cooling events in the surface record during MIS 21 were associated with low benthic carbon isotope excursions, suggesting a coupling between surface temperature changes and the strength of the Atlantic meridional overturning circulation. Time series analysis performed on the whole interval indicates that benthic and planktonic oxygen isotopes have significant concentrations of spectral power centered on periods of 10.7 kyr and 6 kyr, which is in agreement with the second and forth harmonic of precession. The excellent correspondence between the foraminifera δ18O records and insolation variations at the Equator in March and September suggests that a mechanism related to low-latitude precession variations, advected to the high latitudes by tropical convective processes, might have generated such a response. This scenario accounts for the presence of oscillations at frequencies equal to precession harmonics at Site U1313, as well as the occurrence of higher amplitude oscillations between the MIS22/21 transition and most of MIS 21, times of enhanced insolation variability.

The latest version of the planetary ephemerides developed at the Paris Observatory and at the Besançon Observatory is presented. INPOP08 is a 4-dimension ephemeris since it provides positions and velocities of planets and the relation between Terrestrial Time and Barycentric Dynamical Time. Investigations to improve the modeling of asteroids are described as well as the new sets of observations used for the fit of INPOP08. New observations provided by the European Space Agency deduced from the tracking of the Mars Express and Venus Express missions are presented as well as the normal point deduced from the Cassini mission. We show importance of these observations in the fit of INPOP08, especially in terms of Venus, Saturn and Earth-Moon barycenter orbits.

Presented here are the details of the astrometric reductions from the x, y data to mean right ascension (R.A.), declination (decl.) coordinates of the third U.S. Naval Observatory CCD Astrograph Catalog (UCAC3). For these new reductions we used over 216,000 CCD exposures. The Two-Micron All-Sky Survey (2MASS) data are used extensively to probe for coordinate and coma-like systematic errors in UCAC data mainly caused by the poor charge transfer efficiency of the 4K CCD. Errors up to about 200 mas have been corrected using complex look-up tables handling multiple dependences derived from the residuals. Similarly, field distortions and sub-pixel phase errors have also been evaluated using the residuals with respect to 2MASS. The overall magnitude equation is derived from UCAC calibration field observations alone, independent of external catalogs. Systematic errors of positions at the UCAC observing epoch as presented in UCAC3 are better corrected than in the previous catalogs for most stars. The Tycho-2 catalog is used to obtain final positions on the International Celestial Reference Frame. Residuals of the Tycho-2 reference stars show a small magnitude equation (depending on declination zone) that might be inherent in the Tycho-2 catalog.

Efforts to detect gravitational waves by timing an array of pulsars have traditionally focused on stationary gravitational waves, e.g., stochastic or periodic signals. Gravitational wave bursts—signals whose duration is much shorter than the observation period—will also arise in the pulsar timing array waveband. Sources that give rise to detectable bursts include the formation or coalescence of supermassive black holes (SMBHs), the periapsis passage of compact objects in highly elliptic or unbound orbits about an SMBH, or cusps on cosmic strings. Here, we describe how pulsar timing array data may be analyzed to detect and characterize these bursts. Our analysis addresses, in a mutually consistent manner, a hierarchy of three questions. (1) What are the odds that a data set includes the signal from a gravitational wave burst? (2) Assuming the presence of a burst, what is the direction to its source? (3) Assuming the burst propagation direction, what is the burst waveform's time dependence in each of its polarization states? Applying our analysis to synthetic data sets, we find that we can detect gravitational waves even when the radiation is too weak to either localize the source or infer the waveform, and detect and localize sources even when the radiation amplitude is too weak to permit the waveform to be determined. While the context of our discussion is gravitational wave detection via pulsar timing arrays, the analysis itself is directly applicable to gravitational wave detection using either ground- or space-based detector data.

We consider scalar-tensor theories of gravity extended by pseudoscalar couplings to matter and gauge fields and derive constraints on the CP-odd combinations of scalar and pseudoscalar couplings from laboratory spin precession experiments and from the evolution of photon polarization over cosmological distances. We show the complementary character of local and cosmological constraints, and derive novel bounds on the pseudoscalar couplings to photons from the laboratory experiments. It is also shown that the more accurate treatment of the spin content of nuclei used in the spin precession experiments allows us to tighten bounds on Lorentz-violating backgrounds coupled to the proton spin.

We report the discovery of a low-mass companion orbiting the metal-rich, main sequence F star TYC 2949-00557-1 during the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS) pilot project. The host star has an effective temperature T eff = 6135 ± 40 K, logg = 4.4 ± 0.1, and [Fe/H] = 0.32 ± 0.01, indicating a mass of M = 1.25 ± 0.09 M sun and R = 1.15 ± 0.15 R sun. The companion has an orbital period of 5.69449 ± 0.00023 days and straddles the hydrogen burning limit with a minimum mass of 64 MJ , and thus may be an example of the rare class of brown dwarfs orbiting at distances comparable to those of "Hot Jupiters." We present relative photometry that demonstrates that the host star is photometrically stable at the few millimagnitude level on time scales of hours to years, and rules out transits for a companion of radius gsim0.8 RJ at the 95% confidence level. Tidal analysis of the system suggests that the star and companion are likely in a double synchronous state where both rotational and orbital synchronization have been achieved. This is the first low-mass companion detected with a multi-object, dispersed, fixed-delay interferometer.

ESA’s Space Debris Office provides an operational service for the assessment of collision risks of ESA satellites. Currently, the ENVISAT and ERS-2 missions in low Earth orbits are covered by this service. If an upcoming high-risk conjunction event is predicted based on analysis of Two-Line Element (TLE) data from the US Space Surveillance Network, then independent tracking data of the potential high-risk conjunction object are acquired to improve the knowledge of its orbit. This improved knowledge and the associated small error covariances derived from the orbit determination process scale down the position error ellipsoid at the conjunction epoch. Hence, for the same miss-distance, in most cases an avoidance manoeuvre can be suppressed with an acceptable residual risk. During the past years sophisticated stand-alone tools have been developed and maintained at ESA’s Space Debris Office. The central tools for analysing conjunction events are the collision risk assessment software CRASS and the orbit determination software ODIN. ODIN is used to process tracking data and to determine orbits by least-squares fits of tracking data, or of pseudo-data in terms of osculating orbit states, which can for instance be derived from TLEs. On this basis, estimates of TLE error covariances also can be established as input for initial collision risk assessments. For ESA’s automated routine conjunction event assessments which are embedded in a daily process with 7-day predictions, the handling of high-risk events is work-intensive. This shortcoming has been addressed by the implementation of a job scheduler, and automated procedures to facilitate the processing of tracking data, the update of ephemerides and covariances, and the update of conjunction geometries and collision risk estimates. The application of the upgraded software environment is illustrated through two exemplary, recent conjunction events of ENVISAT (02009A) with Russian Cosmos satellites: the conjunction event on 2008-Jan-09 19:00 (UTC) with the chaser object COSMOS-1624 (85006A), and the conjunction event on 2007-Nov-14 13:49 (UTC) with the chaser object COSMOS-1486 (83079A).

The 5th Workshop of Young Researchers in Astronomy and Astrophysics was held on 2–4 September 2009 at the Eötvös University in Budapest, Hungary. This meeting fits into a conference series which can already be considered a tradition where the younger generation has the opportunity to present their work. The event was also a great opportunity for senior astronomers and physicists to form new connections with the next generation of researchers. The selection of invited speakers concentrated on the researchers currently most active in the field, mostly on a post-doctoral/tenure/fresh faculty position level. A number of senior experts and PhD students were also invited. As the conference focused on people rather than a specific field, various topics from theoretical physics to planetology were covered in three days. The programme was divided into six sections: Physics of the Sun and the Solar System, Gravity and high-energy physics, Galactic and extragalactic astronomy, cosmology, Celestial mechanics and exoplanets, Infrared astronomy and young stars, Variable stars We had the pleasure of welcoming 10 invited review talks from senior researchers and 42 contributed talks and a poster from the younger generation. Participants also enjoyed the hospitality of the pub Pál at the Pálvölgyi-cave after giving, hearing and disputing countless talks. Brave souls even descended to the unbuilt, adventurous Mátyásvölgyi-cave. Memories of the conference were shadowed though. Péter Csizmadia, one of our participants and three other climbers attempted a first ever ascent to the Ren Zhong Feng peak in Sichuan, China, but they never returned from the mountains. Péter departed to China shortly after the conference, with best wishes from participants and friends. We dedicate this volume to his memory. The organisers thank the Physics Doctoral School of Eötvös University for its hospitality. The workshop was supported by the Mecenatúra and Polányi Mihály Programmes of the National Office for Research and Technology (NKTH) and the Ministry of Education and Culture (OKM) of Hungary. Emese Forgács-Dajka, Emese Plachy and László Molnár Conference photograph Conference photograph

The knowledge of accurate stellar parameters is paramount in several fields of stellar astrophysics, particularly in the study of extrasolar planets, where often the star is the only visible component and therefore used to infer the planet's fundamental parameters. Another important aspect of the analysis of planetary systems is the stellar activity and the possible star-planet interaction. Here, we present a self-consistent abundance analysis of the planet-hosting star WASP-12 and a high-precision search for a structured stellar magnetic field on the basis of spectropolarimetric observations obtained with the ESPaDOnS spectropolarimeter. Our results show that the star does not have a structured magnetic field, and that the obtained fundamental parameters are in good agreement with what was previously published. In addition, we derive improved constraints on the stellar age (1.0-2.65 Gyr), mass (1.23-1.49 M/Msun, and distance (295-465 pc). WASP-12 is an ideal object in which to look for pollution signatures in the stellar atmosphere. We analyze the WASP-12 abundances as a function of the condensation temperature and compare them with those published by several other authors on planet-hosting and non-planet-hosting stars. We find hints of atmospheric pollution in WASP-12's photosphere but are unable to reach firm conclusions with our present data. We conclude that a differential analysis based on WASP-12 twins will probably clarify whether an atmospheric pollution is present as well as the nature of this pollution and its implications in planet formation and evolution. We also attempt the direct detection of the circumstellar disk through infrared excess, but without success.

Context: While sub-micron- and micron-sized dust grains are generally well mixed with the gas phase in protoplanetary disks, larger grains will be partially decoupled and as a consequence have a different distribution from that of the gas. This has ramifications for predictions of the observability of protoplanetary disks, for which gas-only studies will provide an inaccurate picture. Specifically, criteria for gap opening in the presence of a planet have generally been studied for the gas phase, whereas the situation can be quite different in the dust layer once grains reach mm sizes, which is what will be observed by ALMA.
Aims: We aim to investigate the formation and structure of a planetary gap in the dust layer of a protoplanetary disk with an embedded planet.
Methods: We perform 3D, gas+dust SPH simulations of a protoplanetary disk with a planet on a fixed circular orbit at 40 AU to study the evolution of both the gas and dust distributions and densities in the disk. We run a series of simulations in which the planet mass and the dust grain size varies.
Results:We show that the gap in the dust layer is more striking than in the gas phase and that it is deeper and wider for more massive planets as well as for larger grains. For a massive enough planet, we note that cm-sized grains remain inside the gap in corotation and that their population in the outer disk shows an asymmetric structure, a signature of disk-planet interactions even for a circular planetary orbit, which should be observable with ALMA.

The outer edge of Saturn's B ring is strongly affected by the nearby 2:1 inner Lindblad resonance of Mimas and is distorted approximately into a centered elliptical shape, which at the time of the Voyager 1 and 2 encounters was oriented with its periapse toward Mimas. Subsequent observations have shown that the actual situation is considerably more complex. We present a complete set of historical occultation measurements of the B-ring edge, including the 1980 Voyager 1 and 1981 Voyager 2 radio and stellar occultations, the 1989 occultation of 28 Sgr, two independently analyzed occultations observed with the Hubble Space Telescope in 1991 and 1995, and a series of ring profiles from 12 diametric (ansa-to-ansa) occultations observed in 2005, using the Cassini Radio Science Subsystem (RSS). After making an approximate correction for systematic errors in the reconstructed spacecraft trajectories, we obtain orbit fits to features in the rings with rms residuals well under 1 km, in most cases. Fits to the B-ring edge in the RSS data reveal a systematic variation in the maximum optical depth at the very edge of the ring as a function of its orbital radius. We compare the B-ring measurements to an m = 2 distortion aligned with Mimas, and show that there have been substantial phase shifts over the past 25 years. Finally, we present freely precessing equatorial elliptical models for 16 features in the Cassini Division. The inner edges of the gaps are generally eccentric, whereas the outer edges are nearly circular, with ae < 0.5 km.

Context: The evection resonance appears to be the outermost region of stability for prograde satellite orbiting a planet, the critical argument of the resonance indeed being found librating in regions surrounded only by chaotic orbits. The dynamics of the resonance itself is thus of great interest for the stability of satellites, but its analysis by means of an analytical model is not straightforward because of the high perturbations acting on the dynamical region of interest.
Aims: It is thus important to show the results and the limits inherent in analytical models. We use numerical methods to test the validity of the models and analyze the dynamics of the resonance.
Methods: We use an analytical method based on a classical averaged expansion of the disturbing function valid for all eccentricities as well as numerical integrations of the motion and surfaces of section.
Results: By comparing analytical and numerical methods, we show that aspects of the true resonant dynamic can be represented by our analytical model in a more accurate way than previous approximations, and with the help of the surfaces of section we present the exact location and dynamics of the resonance. We also show the additional region of libration of the resonance that can be found much closer to the planet due to its oblateness.

Time ephemeris is the location-independent part of the transformation formula relating two time coordinates such as TCB and TCG (Fukushima 1995). It is computed from the corresponding (space) ephemerides providing the relative motion of two spatial coordinate origins such as the motion of geocenter relative to the solar system barycenter. The time ephemerides are inevitably needed in conducting precise four dimensional coordinate transformations among various spacetime coordinate systems such as the GCRS and BCRS (Soffel et al. 2003). Also, by means of the time average operation, they are used in determining the information on scale conversion between the pair of coordinate systems, especially the difference of the general relativistic scale factor from unity such as LC. In 1995, we presented the first numerically-integrated time ephemeris, TE245, from JPL's planetary ephemeris DE245 (Fukushima 1995). It gave an estimate of LC as 1.4808268457(10) × 108, which was incorrect by around 2 × 1016. This was caused by taking the wrong sign of the post-Newtonian contribution in the final summation. Four years later, we updated TE245 to TE405 associated with DE405 (Irwin and Fukushima 1999). This time the renewed vale of LC is 1.48082686741(200) × 108. Another four years later, by using a precise technique of time average, we improved the estimate of Newtonian part of LC for TE405 as 1.4808268559(6) × 108 (Harada and Fukushima 2003). This leads to the value of LC as LC= 1.48082686732(110) × 108. If we combine this with the constant defining the mean rate of TCG-TT, LG= 6.969290134 × 1010 (IAU 2001), we estimate the numerical value of another general relativistic scale factor LB= 1.55051976763(110) × 108 which has the meaning of the mean rate of TCB-TT. The main reasons of the uncertainties are the truncation effect in time average and the uncertainty of asteroids' perturbation. The former is a natural limitation caused by the finite length of numerical planetary ephemerides and the latter is due to the uncertainty of masses of some heavy asteroids. As a compact realization of the time ephemeris, we prepared HF2002, a Fortran routine to compute approximate harmonic series of TE405 with the RMS error of 0.446 ns for the period 1600 to 2200 (Harada and Fukushima 2003). It is included in the IERS Convention 2003 (McCarthy and Petit 2003) and available from the IERS web site; http://tai.bipm.org/iers/conv2003/conv2003_c10.html.

Dr. George Kaplan, the current Vice-President of the Commission was nominated to be the new President. Dr. Catherine Hohenkerk was elected to be the next Vice-President of the Commission. As for the Membership of the Organizing Committee, Dr. Vondrak stepped down and Drs William Folkner of JPL and Steve Bell of HMNAO have been added. We present summaries of the reports from various institutions presented at the business session.

We propose in this paper a reliable method for constructing complex networks from a time series with each vector point of the reconstructed phase space represented by a single node and edge determined by the phase space distance. Through investigating an extensive range of network topology statistics, we find that the constructed network inherits the main properties of the time series in its structure. Specifically, periodic series and noisy series convert into regular networks and random networks, respectively, and networks generated from chaotic series typically exhibit small-world and scale-free features. Furthermore, we associate different aspects of the dynamics of the time series with the topological indices of the network and demonstrate how such statistics can be used to distinguish different dynamical regimes. Through analyzing the chaotic time series corrupted by measurement noise, we also indicate the good antinoise ability of our method.

Context:The present work deals with the detection of phase changes in an exoplanetary system. HD 46375 is a solar analog known to host a non-transiting Saturn-mass exoplanet with a 3.0236 day period. It was observed by the CoRoT satellite for 34 days during the fall of 2008.
Aims: We attempt to identify at optical wavelengths, the changing phases of the planet as it orbits its star. We then try to improve the star model by means of a seismic analysis of the same light curve and the use of ground-based spectropolarimetric observations.
Methods: The data analysis relies on the Fourier spectrum and the folding of the time series.
Results: We find evidence of a sinusoidal signal compatible in terms of both amplitude and phase with light reflected by the planet. Its relative amplitude is Δ Fp/Fstar = [13.0, 26.8] ppm, implying an albedo A = [0.16, 0.33] or a dayside visible brightness temperature Tb ≃ [1880, 2030] K by assuming a radius R = 1.1 RJup and an inclination i = 45°. Its orbital phase differs from that of the radial-velocity signal by at most 2 σ_RV. However, the tiny planetary signal is strongly blended by another signal, which we attribute to a telluric signal with a 1 day period. We show that this signal is suppressed, but not eliminated, when using the time series for HD 46179 from the same CoRoT run as a reference.
Conclusions: This detection of reflected light from a non-transiting planet should be confirmable with a longer CoRoT observation of the same field. In any case, it demonstrates that non-transiting planets can be characterized using ultra-precise photometric lightcurves with present-day observations by CoRoT and Kepler. The combined detection of solar-type oscillations on the same targets (Gaulme et al. 2010a) highlights the overlap between exoplanetary science and asteroseismology and shows the high potential of a mission such as Plato.

Einstein's general theory of relativity establishes equality between matter-energy density and the curvature of spacetime. As a result, light and matter follow natural paths in the inherent spacetime and may experience bending and trapping in a specific region of space. So far, the interaction of light and matter with curved spacetime has been predominantly studied theoretically and through astronomical observations. Here, we propose to link the newly emerged field of artificial optical materials to that of celestial mechanics, thus opening the way to investigate light phenomena reminiscent of orbital motion, strange attractors and chaos, in a controlled laboratory environment. The optical-mechanical analogy enables direct studies of critical light/matter behaviour around massive celestial bodies and, on the other hand, points towards the design of novel optical cavities and photon traps for application in microscopic devices and lasers systems.

We analyze galactic black hole mergers and their emitted gravitational waves. Such mergers have typically unequal masses with a mass ratio of order 1/10. The emitted gravitational waves carry the imprint of spins and mass quadrupoles of the binary components. Among these contributions, we consider here the quasi-precessional evolution of the spins. A method of taking into account these third post-Newtonian (3 PN) effects by renormalizing (redefining) the 1.5 PN and 2 PN accurate spin contributions to the accumulated orbital phase is developed.

This paper is the first part of an investigation where we will present an analytical general theory of the rotation of the non-rigid Earth at the second order, which considers the effects of the interaction of the rotation of the Earth with itself, also named as the spin-spin coupling. Here, and as a necessary step in the development of that theory, we derive complete, explicit, analytical formulae of the rigid Earth rotation that account for the second-order rotation-rotation interaction. These expressions are not provided in this form by any current rigid Earth model. Working within the Hamiltonian framework established by Kinoshita, we study the second-order effects arising from the interaction of the main term in the Earth geopotential expansion with itself, and with the complementary term arising when referring the rotational motion to the moving ecliptic. To this aim, we apply a canonical perturbation method to solve analytically the canonical equations at the second order, determining the expressions that provide the nutation-precession, the polar motion, and the length of day. In the case of the motion of the equatorial plane, nutation-precession, we compare our general approach with the particular study for this motion developed by Souchay et al., showing the existence of new terms whose numerical values are within the truncation level of 0.1 µas adopted by those authors. These terms emerge as a consequence of not assuming in this work the same restrictive simplifications taken by Souchay et al. The importance of these additional contributions is that, as the analytical formulae show, they depend on the Earth model considered, in such a way that the fluid core resonance could amplify them significantly when extending this theory to the non-rigid Earth models.

Observations from the recent Whole Heliosphere Interval (WHI) solar minimum campaign are compared to last cycle's Whole Sun Month (WSM) to demonstrate that sunspot numbers, while providing a good measure of solar activity, do not provide sufficient information to gauge solar and heliospheric magnetic complexity and its effect at the Earth. The present solar minimum is exceptionally quiet, with sunspot numbers at their lowest in 75 years and solar wind magnetic field strength lower than ever observed. Despite, or perhaps because of, a global weakness in the heliospheric magnetic field, large near-equatorial coronal holes lingered even as the sunspots disappeared. Consequently, for the months surrounding the WHI campaign, strong, long, and recurring high-speed streams in the solar wind intercepted the Earth in contrast to the weaker and more sporadic streams that occurred around the time of last cycle's WSM campaign. In response, geospace and upper atmospheric parameters continued to ring with the periodicities of the solar wind in a manner that was absent last cycle minimum, and the flux of relativistic electrons in the Earth's outer radiation belt was elevated to levels more than three times higher in WHI than in WSM. Such behavior could not have been predicted using sunspot numbers alone, indicating the importance of considering variation within and between solar minima in analyzing and predicting space weather responses at the Earth during solar quiet intervals, as well as in interpreting the Sun's past behavior as preserved in geological and historical records.

We used Spitzer and its IRAC camera to search for the transit of the super-Earth HD 40307b. The hypothesis that the planet transits could not be firmly discarded from our first photometric monitoring of a transit window because of the uncertainty coming from the modeling of the photometric baseline. To obtain a firm result, two more transit windows were observed and a global Bayesian analysis of the three IRAC time series and the HARPS radial velocities was performed. Unfortunately, the hypothesis that the planet transited during the observed phase window is firmly rejected, while the probability that the planet does transit but that the eclipse was missed by our observations is nearly negligible (0.26%).

We report the discovery by the CoRoT satellite of a new transiting giant planet in a 2.83 days orbit about a V = 15.5 solar analog star (M_* = 1.08 ± 0.08 M_ȯ, R_* = 1.1 ± 0.1 R_ȯ, Teff = 5675 ± 80 K). This new planet, CoRoT-12b, has a mass of 0.92 ± 0.07 MJup and a radius of 1.44 ± 0.13 RJup. Its low density can be explained by standard models for irradiated planets.

We study the stability regions and families of periodic orbits of two planets locked in a co-orbital configuration. We consider different ratios of planetary masses and orbital eccentricities; we also assume that both planets share the same orbital plane. Initially, we perform numerical simulations over a grid of osculating initial conditions to map the regions of stable/chaotic motion and identify equilibrium solutions. These results are later analysed in more detail using a semi-analytical model. Apart from the well-known quasi-satellite orbits and the classical equilibrium Lagrangian points L4 and L5, we also find a new regime of asymmetric periodic solutions. For low eccentricities these are located at σ,Δω = (+/-60°, -/+120°), where σ is the difference in mean longitudes and Δω is the difference in longitudes of pericentre. The position of these anti-Lagrangian solutions changes with the mass ratio and the orbital eccentricities and are found for eccentricities as high as ~0.7. Finally, we also applied a slow mass variation to one of the planets and analysed its effect on an initially asymmetric periodic orbit. We found that the resonant solution is preserved as long as the mass variation is adiabatic, with practically no change in the equilibrium values of the angles.

As any satellite geodesy technique, DORIS can monitor geocenter variations associated to mass changes within the Earth-Atmosphere-Continental hydrosphere-Oceans system. However, especially for the Z-component, corresponding to a translation of the Earth along its rotation axis, the estimated geocenter is usually affected by large systematic errors of unknown cause. By reprocessing old DORIS data, and by analyzing single satellite solutions in the frequency domain, we show that some of these errors are satellite-dependent and related to the current DORIS orbit determination strategy. In particular, a better handling of solar pressure radiation effects on SPOT-2 and TOPEX satellites is proposed which removes a large part of such artifacts. By empirically multiplying the current solar pressure model with a single coefficient (1.03 for TOPEX/Poseidon after 1993.57, and 0.96 before; and 1.08 for SPOT-2) estimated over a long time period, we can improve the measurement noise of the Z-geocenter component from 47.5 to 30.4 mm for the RMS and from 35 to 6 mm for the amplitude of the annual signal. However, the estimated SRP coefficient for SPOT-2 presents greater temporal variability, indicating that a new, dedicated solar radiation pressure model is still needed for precise geodetic applications. In addition, for the TOPEX satellite, a clear discontinuity of unknown cause is also detected on July 27, 1993.

Efforts to place limits on deviations from canonical formulations of electromagnetism and gravity have probed length scales increasing dramatically over time. Historically, these studies have passed through three stages: (1) testing the power in the inverse-square laws of Newton and Coulomb, (2) seeking a nonzero value for the rest mass of photon or graviton, and (3) considering more degrees of freedom, allowing mass while preserving explicit gauge or general-coordinate invariance. Since the previous review the lower limit on the photon Compton wavelength has improved by four orders of magnitude, to about one astronomical unit, and rapid current progress in astronomy makes further advance likely. For gravity there have been vigorous debates about even the concept of graviton rest mass. Meanwhile there are striking observations of astronomical motions that do not fit Einstein gravity with visible sources. "Cold dark matter" (slow, invisible classical particles) fits well at large scales. “Modified Newtonian dynamics” provides the best phenomenology at galactic scales. Satisfying this phenomenology is a requirement if dark matter, perhaps as invisible classical fields, could be correct here too. "Dark energy" might be explained by a graviton-mass-like effect, with associated Compton wavelength comparable to the radius of the visible universe. Significant mass limits are summarized in a table.

We investigate the observational signatures associated with one of the proposed formation scenario for the recently discovered highly eccentric binary millisecond pulsar (MSP) PSR J1903+0327 in the galactic plane. The scenario requires that the MSP to be part of a hierarchical triple (HT), consisting of inner and outer binaries, experiencing the Kozai resonance. Numerical modelling of a bound point-mass HT, while incorporating the effects due to the quadrupolar interactions between the binary orbits and dominant contributions to the general relativistic periastron precession in the inner binary, reveals that, at the present epoch, the orbital eccentricity of the binary MSP should decrease for reasonable ranges in the HT parameters. The estimated decrements in the orbital eccentricity of the inner binary are few parts in 105, substantially higher than the reported accuracies in the estimation of the orbital eccentricity of the binary MSP, while employing various general relativistic timing models for isolated binary pulsars. For wide ranges in the allowed orbital parameters, the estimated rate of change in the eccentricity of the inner binary is orders of magnitude higher than the value recently measured by the pulsar timing analysis. Therefore, we rule out the scenario that the MSP is part of an HT undergoing the Kozai oscillations. The origin of this system in a typical globular cluster is also shown to be less likely than inferred in the discovery paper.

We present the first measurement of the planet frequency beyond the "snow line," for the planet-to-star mass-ratio interval -4.5 < log q < -2, corresponding to the range of ice giants to gas giants. We find \endgraf\vbox{\begin{center}\displaystyle{d^2 N{_pl}\over d\log q\, d\log s} = (0.36\pm 0.15)\;dex^{-2}\end{center}}\noindentat the mean mass ratio q = 5 × 10-4 with no discernible deviation from a flat (Öpik's law) distribution in log-projected separation s. The determination is based on a sample of six planets detected from intensive follow-up observations of high-magnification (A>200) microlensing events during 2005-2008. The sampled host stars have a typical mass M host ~ 0.5 M sun, and detection is sensitive to planets over a range of planet-star-projected separations (s -1 max R E, s max R E), where R E ~ 3.5 AU(M host/M sun)1/2 is the Einstein radius and s max ~ (q/10-4.3)1/3. This corresponds to deprojected separations roughly three times the "snow line." We show that the observations of these events have the properties of a "controlled experiment," which is what permits measurement of absolute planet frequency. High-magnification events are rare, but the survey-plus-follow-up high-magnification channel is very efficient: half of all high-mag events were successfully monitored and half of these yielded planet detections. The extremely high sensitivity of high-mag events leads to a policy of monitoring them as intensively as possible, independent of whether they show evidence of planets. This is what allows us to construct an unbiased sample. The planet frequency derived from microlensing is a factor 8 larger than the one derived from Doppler studies at factor ~25 smaller star-planet separations (i.e., periods 2-2000 days). However, this difference is basically consistent with the gradient derived from Doppler studies (when extrapolated well beyond the separations from which it is measured). This suggests a universal separation distribution across 2 dex in planet-star separation, 2 dex in mass ratio, and 0.3 dex in host mass. Finally, if all planetary systems were "analogs" of the solar system, our sample would have yielded 18.2 planets (11.4 "Jupiters," 6.4 "Saturns," 0.3 "Uranuses," 0.2 "Neptunes") including 6.1 systems with two or more planet detections. This compares to six planets including one two-planet system in the actual sample, implying a first estimate of 1/6 for the frequency of solar-like systems.

Positron measurements in cosmic rays, studies of gravitational wave emission from isolated pulsars and observations of circumpulsar supernova fallback disks allow us to set upper limits on several energy loss mechanisms of young and mature pulsars. Presently, the above experimental evidences do not lead to conflicting scenarios. In particular, we focus on pulsar spin down due to friction or propeller torque from supernova fallback disks. Gravitational wave emission from circumpulsar planetary systems or precessing disks does not play a relevant role in pulsar spin down. However, the detection of gravitational waves from these systems with future space interferometers would allow us to estimate the fraction of pulsars surrounded by disks. While the planetary system detection appears to be unfeasible, the DECI-Hertz Interferometer Gravitational Wave Observatory (DECIGO) and the Big Bang Observatory (BBO) might reveal the presence of precessing disks.

Based on the available celestial intermediate pole (CIP) coordinate determinations from VLBI observations over the last 25 years, we have constructed a new highly accurate combined series of CIP coordinates. An amplitude-phase analysis of this series has allowed us to improve the previously estimated retrograde free core nutation (RFCN) parameters as functions of time. During this interval, the RFCN period changed several times. It was 418.1 ± 0.2 days before 1992.1 and then 431.6 ± 0.2 days until 1999.0. In 1999, the CIP oscillations damped out almost completely and the process was restructured. Since 2000, the amplitude of these oscillations has increased and their period has become 450.7± 0.1 days.

We study the dynamics of planetary systems with two planets moving in the same plane, when frictional forces act on the two planets, in addition to the gravitational forces. The model of the general three-body problem is used. Different laws of friction are considered. The topology of the phase space is essential in understanding the evolution of the system. The topology is determined by the families of stable and unstable periodic orbits, both symmetric and non symmetric. It is along the stable families, or close to them, that the planets migrate when dissipative forces act. At the critical points where the stability along the family changes, there is a bifurcation of a new family of stable periodic orbits and the migration process changes route and follows the new stable family up to large eccentricities or to a chaotic region. We consider both resonant and non resonant planetary systems. The 2/1, 3/1 and 3/2 resonances are studied. The migration to larger or smaller eccentricities depends on the particular law of friction. Also, in some cases the semimajor axes increase and in other cases they are stabilized. For particular laws of friction and for special values of the parameters of the frictional forces, it is possible to have partially stationary solutions, where the eccentricities and the semimajor axes are fixed.

Like ancient people at other places of the world, the ancient Chinese lived in awe of the Sun. As they felt solar eclipses extremely significant events, they closely observed the occurrence of solar eclipse. Ancient astronomers further realized very early that solar eclipses were one of the important astronomical phenomena to revise and improve the ancient calendar. Interestingly, ancient emperors regarded solar eclipses as warnings from heaven that might affect the stability of their throne. Consequently, observing and recording solar eclipses became official, which dated far back to ancient China when numerous relevant descriptions were recorded in historical books. These records contribute substantially to China as an ancient civilization, as well as to the research of the long-term variation of the rotation rate of the Earth during > 2000 years before the 17th century. This paper briefly reviews the perception, observations and recording of solar eclipses by ancient Chinese astronomers.

Numerical-relativity (NR) simulations of compact binaries are expected to be an invaluable tool in gravitational-wave astronomy. The sensitivity of future detectors such as the Einstein Telescope (ET) will place much higher demands on NR simulations than first- and second-generation ground-based detectors. We discuss the issues facing compact-object simulations over the next decade, with an emphasis on estimating where the accuracy and parameter space coverage will be sufficient for ET and where significant work is needed.

In order to investigate the dependence of planet formation on stellar mass, we have been monitoring a sample of F-type main-sequence stars with the 2.0 m Alfred-Jensch telescope of the Thüringer Landessternwarte Tautenburg. This survey is based on high-precision radial velocity (RV) measurements using the coudé échelle spectrograph and an iodine absorption cell. We present RV measurements of the F7 V star HD 8673 that show a long-term variability of 1634 days with a semi-amplitude K = 288 m s-1 that can be explained most reasonably by an orbiting sub-stellar companion with a minimum mass of 14.2 MJup in a high-eccentricity (e = 0.723) Keplerian orbit. Based on observations obtained at the 2.0-m Alfred-Jensch telescope at the Thüringer Landessternwarte Tautenburg.

Context:CoRoT-7b, the first transiting “superearth” exoplanet, has a radius of 1.7 R⊕ and a mass of 4.8 M⊕. The HARPS radial velocity (RV) measurements used for deriving this mass also detected an additional companion with a period of 3.7 days and a mass of 8.4 M⊕. The mass of CoRoT-7b is a crucial parameter for planet structure models, but is difficult to determine because CoRoT-7 is a modestly active star and there is at least one additional companion.
Aims:The aims of this paper are to assess the statistical significance of the RV variations of CoRoT-7b and CoRoT-7c, to obtain a better measurement of the planet mass for CoRoT-7b, and to search for additional companions in the RV data.
Methods:A Fourier analysis is performed on the HARPS spectral data of CoRoT-7. These data include RV measurements, spectral line bisectors, the full width at half maximum of the cross-correlation function, and Ca II emission. The latter 3 quantities vary due to stellar activity and were used to assess the nature of the observed RV variations. An analysis of a sub-set of the RV measurements where multiple observations were made per night was also used to estimate the RV amplitude from CoRoT-7b that was less sensitive to activity variations.
Results:Our analysis indicates that the 0.85-d and 3.7-d RV signals of CoRoT-7b and CoRoT-7c are present in the spectral data with a high degree of statistical significance. We also find evidence for another significant RV signal at 9 days. An analysis of the activity indicator data reveals that this 9-d signal most likely does not arise from activity, but possibly from an additional companion. If due to a planetary companion the mass is m = 19.5 M⊕, assuming co-planarity with CoRoT-7b. A dynamical study of the three planet system shows that it is stable over several hundred millions of years. Our analysis yields a RV amplitude of 5.04 ± 1.09 m s-1 for CoRoT-7b which corresponds to a planet mass of m = 6.9 ± 1.4 M⊕. This increased mass would make the planet CoRoT-7b more Earth-like in its internal structure.
Conclusions:CoRoT-7 is confirmed to be a planet system with at least 2 and possibly 3 exoplanets having masses in the range 7-20 M⊕. If the third companion can be confirmed then CoRoT-7 may represent a case of an ultra-compact planetary system.

We report on some simple experiments on the nature of chaos in our planetary system. We make the following interesting observations. First, we look at the system of Sun + four Jovian planets as an isolated five-body system interacting only via Newtonian gravity. We find that if we measure the Lyapunov time of this system across thousands of initial conditions all within observational uncertainty, then the value of the Lyapunov time seems relatively smooth across some regions of initial condition space, while in other regions it fluctuates wildly on scales as small as we can reliably measure using numerical methods. This probably indicates a fractal structure of Lyapunov exponents measured across initial condition space. Then, we add the four inner terrestrial planets and several post-Newtonian corrections such as general relativity into the model. In this more realistic Sun + eight-planet system, we find that the above structure of chaos for the outer planets becomes uniformly chaotic for almost all planets and almost all initial conditions, with a Lyapunov time-scale of about 5-20 Myr. This seems to indicate that the addition of the inner planets adds more chaos to the system. Finally, we show that if we instead remove the outer planets and look at the isolated five-body system of the Sun + four terrestrial planets, then the terrestrial planets alone show no evidence of chaos at all, over a large range of initial conditions inside the observational error volume. We thus conclude that the uniformity of chaos in the outer planets comes not from the inner planets themselves, but from the interplay between the outer and inner ones. Interestingly, however, here exist rare and isolated initial conditions for which one individual outer planetary orbit may appear integrable over a 200-Myr time-scale, while all the other planets simultaneously appear chaotic.

The Cassini Division in Saturn's rings contains a series of eight named gaps, three of which contain dense ringlets. Observations of stellar occultations by the Visual and Infrared Mapping Spectrometer onboard the Cassini spacecraft have yielded ~40 accurate and precise measurements of the radial position of the edges of all of these gaps and ringlets. These data reveal suggestive patterns in the shapes of many of the gap edges: the outer edges of the five gaps without ringlets are circular to within 1 km, while the inner edges of six of the gaps are eccentric, with apsidal precession rates consistent with those expected for eccentric orbits near each edge. Intriguingly, the pattern speeds of these eccentric inner gap edges, together with that of the eccentric Huygens Ringlet, form a series with a characteristic spacing of 006 day-1. The two gaps with non-eccentric inner edges lie near first-order inner Lindblad resonances (ILRs) with moons. One such edge is close to the 5:4 ILR with Prometheus, and the radial excursions of this edge do appear to have an m = 5 component aligned with that moon. The other resonantly confined edge is the outer edge of the B ring, which lies near the 2:1 Mimas ILR. Detailed investigation of the B-ring-edge data confirm the presence of an m = 2 perturbation on the B-ring edge, but also show that during the course of the Cassini Mission, this pattern has drifted backward relative to Mimas. Comparisons with earlier occultation measurements going back to Voyager suggest the possibility that the m = 2 pattern is actually librating relative to Mimas with a libration frequency L ~ 006 day-1 (or possibly 012 day-1). In addition to the m = 2 pattern, the B-ring edge also has an m = 1 component that rotates around the planet at a rate close to the expected apsidal precession rate (~5.06°day-1). Thus, the pattern speeds of the eccentric edges in the Cassini Division can be generated from various combinations of the pattern speeds of structures observed on the edge of the B ring: for j = 1, 2, 3, ..., 7. We therefore suggest that most of the gaps in the Cassini Division are produced by resonances involving perturbations from the massive edge of the B ring. We find that a combination of gravitational perturbations generated by the radial excursions in the B-ring edge and the gravitational perturbations from the Mimas 2:1 ILR yields terms in the equations of motion that should act to constrain the pericenter location of particle orbits in the vicinity of each of the eccentric inner gap edges in the Cassini Division. This alignment of pericenters could be responsible for forming the Cassini-Division Gaps and thus explain why these gaps are located where they are.

Context. 2MASS J05352184-0546085 (2M0535-05) is the only known eclipsing brown dwarf (BD) binary, and so may serve as a benchmark for models of BD formation and evolution. However, theoretical predictions of the system's properties seem inconsistent with observations: i) the more massive (primary) component is observed to be cooler than the less massive (secondary) one; ii) the secondary is more luminous (by ≈1024 W) than expected. Previous explanations for the temperature reversal have invoked reduced convective efficiency in the structure of the primary, connected to magnetic activity and to surface spots, but these explanations cannot account for the enhanced luminosity of the secondary. Previous studies also considered the possibility that the secondary is younger than the primary. Aims: We study the impact of tidal heating to the energy budget of both components to determine if it can account for the observed temperature reversal and the high luminosity of the secondary. We also compare various plausible tidal models to determine a range of predicted properties. Methods: We apply two versions of two different, well-known models for tidal interaction, respectively: i) the "constant-phase-lag" model; and ii) the "constant-time-lag" model and incorporate the predicted tidal heating into a model of BD structure. The four models differ in their assumptions about the rotational behavior of the bodies, the system's eccentricity and putative misalignments Ψ between the bodies' equatorial planes and the orbital plane of the system. Results: The contribution of heat from tides in 2M0535-05 alone may only be large enough to account for the discrepancies between observation and theory in an unlikely region of the parameter space. The tidal quality factor QBD of BDs would have to be 103.5 and the secondary needs a spin-orbit misalignment of ≥ 50°. However, tidal synchronization time scales for 2M0535-05 restrict the tidal dissipation function to log(QBD) ≥ 4.5 and rule out intense tidal heating in 2M0535-05. We provide the first constraint on Q for BDs. Conclusions: Tidal heating alone is unlikely to be responsible for the surprising temperature reversal within 2M0535-05. But an evolutionary embedment of tidal effects and a coupled treatment with the structural evolution of the BDs is necessary to corroborate or refute this result. The heating could have slowed down the BDs' shrinking and cooling processes after the birth of the system ≈1 Myr ago, leading to a feedback between tidal inflation and tidal heating. Observations of old BD binaries and measurements of the Rossiter-McLaughlin effect for 2M0535-05 can provide further constraints on QBD.

The `hot Jupiters' that abound in lists of known extrasolar planets are thought to have formed far from their host stars, but migrate inwards through interactions with the proto-planetary disk from which they were born, or by an alternative mechanism such as planet-planet scattering. The hot Jupiters closest to their parent stars, at orbital distances of only ~0.02 astronomical units, have strong tidal interactions, and systems such as OGLE-TR-56 have been suggested as tests of tidal dissipation theory. Here we report the discovery of planet WASP-18b with an orbital period of 0.94 days and a mass of ten Jupiter masses (10MJup), resulting in a tidal interaction an order of magnitude stronger than that of planet OGLE-TR-56b. Under the assumption that the tidal-dissipation parameter Q of the host star is of the order of 106, as measured for Solar System bodies and binary stars and as often applied to extrasolar planets, WASP-18b will be spiraling inwards on a timescale less than a thousandth that of the lifetime of its host star. Therefore either WASP-18 is in a rare, exceptionally short-lived state, or the tidal dissipation in this system (and possibly other hot-Jupiter systems) must be much weaker than in the Solar System.

We derive the universal solution to the Kepler-Coulomb problem with an additional inverse-square potential, valid for any type of orbit, and describe three prominent applications in astrodynamics: the relativistic precession of the apsides, the numerical integration of perturbed Kepler-Coulomb problems with a generalized leapfrog, and the averaged motion of earth-orbiting satellites with the J2 perturbation. The modified orbital elements and Delaunay variables are presented as well.

Turbulent, two-dimensional, hydrodynamic flows are characterized by the emergence of coherent, long-lived vortices without a need to invoke special initial conditions. Vortices have the ability to sequester particles, with typical radii ~1mm to ~10cm, that are slightly decoupled from the gas. A generic feature of discs with surface density and effective temperature profiles that are decreasing, power-law functions of radial distance is that four vortex zones exist for a fixed particle size. In particular, two of the zones form an annulus at intermediate radial distances within which small particles reside. Particle capture by vortices occurs on a dynamical time-scale near and at the boundaries of this annulus. As the disc ages and the particles grow via coagulation, the size of the annulus shrinks. Older discs prefer to capture smaller particles because the gas surface density decreases with time, a phenomenon we term `vortex ageing'. More viscous, more dust-opaque and/or less massive discs can have vortices that age faster and trap a broader range of particle sizes throughout the lifetime of the disc. Thus, how efficiently a disc retains its mass in solids depends on the relative time-scales between coagulation and vortex ageing. If vortices form in protoplanetary discs, they are important in discs with typical masses and for particles that are likely to condense out of the protostellar nebula. Particle capture also occurs at distances relevant to planet formation. Future infrared, submillimetre and centimetre observations of grain opacity as a function of radial distance will test the hypothesis that vortices serve as nurseries for particle growth in protoplanetary discs.

Tidal friction in exoplanet systems, driven by orbits that allow for durable nonzero eccentricities at short heliocentric periods, can generate internal heating far in excess of the conditions observed in our own solar system. Secular perturbations or a notional 2:1 resonance between a hot Earth and hot Jupiter can be used as a baseline to consider the thermal evolution of convecting bodies subject to strong viscoelastic tidal heating. We compare results first from simple models using a fixed Quality factor and Love number, and then for three different viscoelastic rheologies: the Maxwell body, the Standard Anelastic Solid (SAS), and the Burgers body. The SAS and Burgers models are shown to alter the potential for extreme tidal heating by introducing the possibility of new equilibria and multiple response peaks. We find that tidal heating tends to exceed radionuclide heating at periods below 10-30 days, and exceed insolation only below 1-2 days. Extreme cases produce enough tidal heat to initiate global-scale partial melting, and an analysis of tidal limiting mechanisms such as advective cooling for earthlike planets is discussed. To explore long-term behaviors, we map equilibria points between convective heat loss and tidal heat input as functions of eccentricity. For the periods and magnitudes discussed, we show that tidal heating, if significant, is generally detrimental to the width of habitable zones.

We have used four telescopes at different longitudes to obtain near-continuous light-curve coverage of the star HD80606 as it was transited by its ~4-MJup planet. The observations were performed during the predicted transit windows around 2008 October 25 and 2009 February 14. Our data set is unique in that it simultaneously constrains the duration of the transit and the planet's period. Our Markov Chain Monte Carlo analysis of the light curves, combined with constraints from radial-velocity data, yields system parameters consistent with previously reported values. We find a planet-to-star radius ratio marginally smaller than previously reported, corresponding to a planet radius of Rp = 0.921 +/- 0.036RJup.

We apply the Mean Exponential Growth Factor of Nearby Orbits (MEGNO) technique to the dynamics of Jovian irregular satellites. The MEGNO indicator is a practical numerical tool to distinguish between quasi-periodic and chaotic structures in phase space of a given dynamical system. The MEGNO indicator is used to generate a mapping of relevant phase-space regions occupied by observed Jovian irregular satellites. The construction of MEGNO maps of the Jovian phase-space region within its Hill-sphere is addressed and the obtained results are compared with previous studies regarding the dynamical stability of irregular satellites. Since this is the first time the MEGNO technique is applied to study the dynamics of irregular satellites, we provide a review of the MEGNO theory and illustrate basic properties. We consider the elliptic restricted three-body problem in which Jupiter is orbited by a massless test satellite subject to solar gravitational perturbations. The equations of motion of the system are integrated numerically and the MEGNO indicator computed from the system's variational equations. A large set of initial conditions is studied to generate the MEGNO maps. The chaotic nature of initial conditions is demonstrated by studying a quasi-periodic orbit and a chaotic orbit. As a result, we establish the existence of several high-order mean-motion resonances (MMR) detected for retrograde orbits along with other interesting dynamical features related to various dynamical resonances. The computed MEGNO maps allow us to differentiate qualitatively between chaotic and quasi-periodic regions of the irregular satellite phase space within a relatively short integration time of 60000yr for each orbit. By comparing with previous published results, we can establish a correlation between chaotic regions and corresponding regions of orbital instability. Based on our results, we hypothesize on the possibility of gravitational scattering from high-order MMR as a dynamical cause to explain the observed orbital velocity dispersion for members of the Pasiphae family.

The PULSE@Parkes project has been designed to monitor the rotation of radio pulsars over time spans of days to years. The observations are obtained using the Parkes 64-m and 12-m radio telescopes by Australian and international high school students. These students learn the basis of radio astronomy and undertake small projects with their observations. The data are fully calibrated and obtained with the state-of-the-art pulsar hardware available at Parkes. The final data sets are archived and are currently being used to carry out studies of 1) pulsar glitches, 2) timing noise, 3) pulse profile stability over long time scales and 4) the extreme nulling phenomenon. The data are also included in other projects such as gamma-ray observatory support and for the Parkes Pulsar Timing Array project. In this paper we describe the current status of the project and present the first scientific results from the Parkes 12-m radio telescope. We emphasise that this project offers a straightforward means to enthuse high school students and the general public about radio astronomy while obtaining scientifically valuable data sets.

The ESA space astrometry mission Gaia, due for launch in early 2012, will in addition to its huge output of fundamental astrometric and astrophysical data also provide stringent tests of general relativity. In this paper we present an updated analysis of Gaia's capacity to measure the PPN parameter γ as part of its core astrometric solution. The analysis is based on small-scale astrometric solutions taking into account the simultaneous determination of stellar astrometric parameters and the satellite attitude. In particular, the statistical correlation between PPN γ and the stellar parallaxes is considered. Extrapolating the results to a full-scale solution using some 100 million stars, we find that PPN γ could be obtained to about 10‑6, which is significantly better than today's best estimate from the Cassini mission of 2 × 10‑5.

The International Pulsar Timing Array project combines observations of pulsars from both northern and southern hemisphere observatories with the main aim of detecting ultra-low frequency (~ 109 -108 Hz) gravitational waves. Here we introduce the project, review the methods used to search for gravitational waves emitted from coalescing supermassive binary black-hole systems in the centres of merging galaxies and discuss the status of the project.

We provide an analysis of timing irregularities observed for 366 pulsars. Observations were obtained using the 76-m Lovell radio telescope at the Jodrell Bank Observatory over the past 36 years. These data sets have allowed us to carry out the first large-scale analysis of pulsar timing noise over time-scales of >10yr, with multiple observing frequencies and for a large sample of pulsars. Our sample includes both normal and recycled pulsars. The timing residuals for the pulsars with the smallest characteristic ages are shown to be dominated by the recovery from glitch events, whereas the timing irregularities seen for older pulsars are quasi-periodic. We emphasize that previous models that explained timing residuals as a low-frequency noise process are not consistent with observation.

Context. Sodium laser guide stars (LGS) are about to enter a new range of laser powers. Previous theoretical and numerical methods are inadequate for accurate computations of the return flux, hence for the design of the next-generation LGS systems.
Aims: We numerically optimize the cw (continuous wave) laser format, in particular, the light polarization and spectrum.
Methods: Using Bloch equations, we simulate the mesospheric sodium atoms, including Doppler broadening, saturation, collisional relaxation, Larmor precession, and recoil, taking all 24 sodium hyperfine states into account and 100-300 velocity groups.
Results: LGS return flux is limited by ”three evils”: Larmor precession due to the geomagnetic field, atomic recoil due to radiation pressure, and transition saturation. We study their impact and show that the return flux can be boosted by repumping (simultaneous excitation of the sodium D2a and D2b lines with 10-20% of the laser power in the latter).
Conclusions: We strongly recommend the use of circularly polarized lasers and repumping. As a rule of thumb, the bandwidth of laser radiation in MHz (at each line) should approximately equal the launched laser power in Watts divided by six, assuming a diffraction-limited spot size.

Since early work on the stability of the first Neptunian Trojan, 2001 QR322, suggested that it was a dynamically stable, primordial body, it has been assumed that this applies to both that object and its more recently discovered brethren. However, it seems that things are no longer so clear-cut. In this work, we present the results of detailed dynamical simulations of the orbital behaviour of 2001 QR322. Using an ephemeris for the object that has significantly improved since earlier works, we follow the evolution of 19683 test particles, placed on orbits within the observational error ellipse of 2001 QR322's orbit, for a period of 1Gyr. We find that majority of these `clones' of 2001 QR322 are dynamically unstable, exhibiting a near-exponential decay from both the Neptunian Trojan cloud (decay half-life of ~550Myr) and the Solar system (decay half-life of ~590Myr). The stability of the object within Neptune's Trojan cloud is found to be strongly dependent on the initial semimajor axis used, with these objects located at a >= 30.30au being significantly less stable than those interior to this value, as a result of their having initial libration amplitudes very close to a critical threshold dividing regular and irregular motion, located at ~70°-75° (full extent of angular motion). This result suggests that if 2001 QR322 is a primordial Neptunian Trojan, it must be a representative of a population that was once significantly larger than that we see today and adds weight to the idea that the Neptune Trojans may represent a significant source of objects moving on unstable orbits between the giant planets (the Centaurs).

The fact that the Centaurs are the primary source of the short-period comets is well established. However, the origin of the Centaurs themselves is still under some debate, with a variety of different source reservoirs being proposed in the last decade. In this work, we suggest that the Neptune Trojans (together with the Jovian Trojans) could represent an additional significant source of Centaurs. Using dynamical simulations of the first Neptune Trojan discovered (2001 QR322), together with integrations following the evolution of clouds of theoretical Neptune Trojans obtained during simulations of planetary migration, we show that the Neptune Trojan population contains a great number of objects which are unstable on both Myr and Gyr time-scales. Using individual examples, we show how objects that leave the Neptunian Trojan cloud evolve on to orbits indistinguishable from those of the known Centaurs, before providing a range of estimates of the flux from this region to the Centaur population. With only moderate assumptions, it is shown that the Trojans can contribute a significant proportion of the Centaur population, and may even be the dominant source reservoir. This result is supported by past work on the colours of the Trojans and the Centaurs, but it will take future observations to determine the full scale of the contribution of the escaped Trojans to the Centaur population.

We test the fixed hot spot and fixed spin axis hypotheses through a paleomagnetic investigation of the skewness of crossings of magnetic anomaly 12r (32 Ma B.P.) between the Galapagos and Clarion fracture zones on the Pacific plate. We focus on this region for three reasons. First, numerical experiments show that these crossings, of all those available from the Pacific plate, should contain the most information about the location of the 32 Ma B.P. paleomagnetic pole for the Pacific plate. Second, many of the available crossings are from vector aeromagnetic profiles, which have superior signal-to-noise ratios. Third, the rate of seafloor spreading recorded in these crossings exceeds the threshold (half rate of 50 mm a 1) above which anomalous skewness is negligible. The new pole (83.5°N, 44.6°E) has compact 95% confidence limits (ellipse with major semiaxis length of 3.1° toward 84° clockwise from north and minor semiaxis length of 1.2°) and is not subject to the biases inherent in other methods for estimating Pacific plate paleomagnetic poles. The pole differs significantly by ≈5° from the pole predicted if the Pacific hot spots have been fixed with respect to the spin axis, thus demonstrating, for the first time from paleomagnetic data, that Pacific hot spots have moved relative to the spin axis since the formation of the elbow in the Hawaiian-Emperor chain. The pole is consistent, however, with previously published paleomagnetic poles in a reference frame fixed relative to Indo-Atlantic hot spots. Thus, the new results require no motion between Pacific and Indo-Atlantic hot spots since 32 Ma B.P. Instead, superimposed on whatever motion occurs between hot spots, as expected for true polar wander.

The late stages of evolution of the primordial circumstellar disks surrounding young stars are poorly understood, yet vital to constraining theories of planet formation. We consider basic structural models for the disks around two ~10 Myr old members of the nearby RCrA association:

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