We investigate the old open cluster M67 using ultraviolet photometric data of Ultra-Violet Imaging Telescope in multi-filter far-UV bands. M67, well known for the presence of several blue straggler stars (BSS), has been put to detailed tests to understand their formation pathways. Currently, there are three accepted formation channels: mass transfer due to Roche-lobe overflow in binary systems, stellar mergers either due to dynamical collisions or through coalescence of close binaries. So far, there had not been any confirmed detection of a white dwarf (WD) companion to any of the BSSs in this cluster. Here, we present the detection of WD companions to 5 bright BSSs in M67. The multiwavelength spectral energy distributions covering 0.12 -11.5 μm range, were found to require binary spectral fits for 5 BSSs, consisting of a cool (BSS) and a hot companion. The parameters (Luminosity, Temperature, Radius and Mass) of the hot companions suggest them to be WDs with mass in the range 0.2 - 0.35 M⊙ with Teff ~11000 –24000 K.

In this article we examine the motion of fictitious Trojan planets close to the equilateral Lagrangean equilibrium points in extrasolar planetary systems. Whether there exist stable motion in this area or not depends on the massratio of the primariy bodies in the restricted three body problem, namely the host star and the gasgiant. Taking into account also the eccentricity of the primaries we show via results of extensive numerical integrations that Trojan planets may survive only for e < 0.25. We also show first results of a mapping in the 1:1 resonance with a gas giant on an eccentric orbit which is applied to the extrasolar planetary systems HD 17051. We furthermore study the influence of an additional outer planet which perturbs the motion of the gasgiant as well as the Trojan cloud around its L4 Lagrangean point.

The ILS results reduced to a uniform system give a motion of the pole of 0′′.0032/year in the direction 70°W. The latitude of Mizusawa decreases 0′′.003/yr and that of Ukiah increases at the same rate. This confirms the geological theory which indicates a counter-clockwise rotation of the coasts of the Pacific.

We present an overview of the European Space Agency's Planck mission, its scientific objectives, and the key elements of its technical design. The current programmatic status of Planck within ESA's Scientific Programme, implementation plans, and near-term milestones, are also addressed.

The accuracy of the rigid-Earth solution SMART97 is 2 μas over the time interval (1968, 2023). To obtain a nonrigid-Earth solution, we use the transfer function of Mathews (1999). The perturbations of the third component of the angular velocity vector are taken into account.

Over the past two years, we have obtained high resolution high signal/noise (S/N) spectra of the magnetic Be star σ Ori E at the Canada-France-Hawaii Telescope and McDonald Observatory. These spectra, which cover the spectral regions 399-417.5 and 440-458.5 nm and the Hα line and have typical S/N>200 and spectral resolution ≃0.02 nm, were obtained at a variety of rotational phases in order to study the magnetic field structure, the distribution of elements in the photosphere, and the effects of the magnetic field on the emission envelope. Our analysis of these spectra confirms, refines and extends the results obtained by Landstreet & Borra (1978), Groote & Hunger (1982 and references therein), and Nakajima (1985).

The Hα emission is usually double-peaked, but it undergoes remarkable variations with the 1.19081 d rotational period of the star, which show that the emitting gas is localized into two regions which co-rotate with the star.

Chinese Giant Solar Telescope is the next generation ground-based solar telescope. The main science task of this telescope is to observe the ultra fine structures of the solar magnetic field and dynamic field. Due to the advantages in polarization detection and thermal controlling with a symmetrical circular system, the current design of CGST is a 6~8 meter circular symmetrical telescope. The results of simulations and analysis showed that the current design could meet the demands of most science cases not only in infrared bands but also in near infrared bands and even in visible bands. The prominences and the filaments are very important science cases of CGST. The special technologies for prominence observation will be developed, including the day time laser guide star and MCAO. CGST is proposed by all solar observatories and several institutes and universities in China. It is supported by CAS and NSFC (National Natural Science Foundation of China) as a long term astronomical project.

Division 5 of the CIE deals with the subject of “Exterior and other Lighting Applications” and has since 1991 had a Technical Committee (TC5.12) working on a “Guide on the limitation of the effects of obtrusive light from outdoor lighting installations”. This Committee did much of its work under the chairmanship of Dr. Alec Fisher of Australia, who has now retired and passed on the work to the current author. The present report outlines the content of the proposed Guide and details its relevance to help preserve the astronomical sky. It also highlights the close links with CIE Committee TC4.21, which works directly on the problems of sky glow.

A complete study is made of the 5/2 resonant motion of two planets revolving around a star, in the model of the general planar three body problem. Families of 5/2 resonant symmetric periodic orbits are computed numerically, for the masses of the extrasolar system 47 UMa. The phase of the two planets (alignment or antialignment of perihelia and position of each planet at perihelion or aphelion) plays an important role, and the change of the phase, other things being the same, may destabilize the system. Stable motion exists even in the case where the two planetary orbits intersect. A small value of the eccentricities, for the same phase, stabilizes the system. The above results are applied to the study of 47 UMa, which according to some observations is close to the 5/2 resonance.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A VLBA image of the X-ray binary Cyg X-3 made two days after a 10 Jy radio flare shows a one-sided, curved jet with a size scale of ≈60 mas. This seems to indicate a jet with a velocity of ≥0.89c with a inclination of a few degrees to the line of site, and indicates that some of events where Cyg X-3 flares above 3 Jy may come from highly relativistic jets close to the line of sight.

We give here a detailed technical description of a Monte Carlo scheme for the dynamical evolution of spherical stellar systems. The philosophy of the method, as well as a few illustrative results, are given elsewhere (Hénon, 1971, hereafter called I).

Photometric measurements of the emission nebulosities in the LMC are not numerous. Doherty, Henize, and Aller (1956) microphotometered both widened and unwidened objective-prism photographs covering a narrow wavelength range near Hα to obtain cross-sectional “intensity profiles” for certain nebulosities in the Large Cloud. These intensities were converted to surface brightnesses by tracing the widened spectra of stars of known magnitude and colour and using the method of Ambartsumian (1933). Peak intensities for each scan across a nebulosity are given in erg cm–2 sec–1 steradian–1.

In preparation for observations with the James Webb Space Telescope (JWST), we have identified new members of the nearby, young M dwarf sample and compiled an up to date list of these stars. Here we summarize our efforts to identify young M dwarfs, describe the current sample, and detail its demographics in the context of direct planet imaging. We also describe our investigations of the unprecedented sensitivity of the JWST when imaging nearby, young M dwarfs. The JWST is the only near term facility capable of routinely pushing direct imaging capabilities around M dwarfs to sub-Jovian masses and will provide key insight into questions regarding low-mass gas-giant properties, frequency, formation, and architectures.

We give an update of the observations and analysis of G2 – the gaseous red emission-line object that is on a very eccentric orbit around the Galaxy's central black hole and predicted to come within 2400 RS in early 2014. During 2013, the laser guide star adaptive optics systems on the W. M. Keck I and II telescopes were used to obtain three epochs of spectroscopy and imaging at the highest spatial resolution currently possible in the near-IR. The updated orbital solution derived from radial velocities in addition to Br-γ line astrometry is consistent with our earlier estimates. Strikingly, even ∼ 6 months before pericenter passage there is no perceptible deviation from a Keplerian orbit. We furthermore show that a proposed “tail” of G2 is likely not associated with it but is rather an independent gas structure. We also show that G2 does not seem to be unique, since several red emission-line objects can be found in the central arcsecond. Taken together, it seems more likely that G2 is ultimately stellar in nature, although there is clearly gas associated with it.

In the preceding lecture Dr Arnett has shown us how exciting the inner life of a star can be when during late stages of evolution higher nuclear reactions take place. But in order to enjoy the variety of different nuclear species formed there stellar material from the deep interior has to be brought up to the surface, where the observers can see it.

For many comets the accelerations radially from the Sun have been determined by deviations from gravitational orbits. The radial force per unit area can be calculated on the basis of certain assumptions concerning the nature of the vaporizing material, the physical circumstances, and the geometry of the cometary nucleus. The observed accelerations combined with the calculated forces yield numerical values for (1-A)/R where A is the albedo, and R the radius of the nucleus. At extreme solar distances photometry provides the well-known quantity area-times-albedo or RA1/2. Solutions are then possible for R and A for the nuclei of the comets. The derived quantity, (1-A)A1/2, provides a limiting check on the basic assumptions and, therefore, on the basic physical properties of the nuclei. For ten short-period comets with q < 1.5 AU, the observations are satisfied by H2O ice. About half show “spotty” surfaces.

For comets of a single apparition H2O ice is generally not volatile enough to produce the observed radial accelerations. The resulting problems are discussed including the possibility that in some cases displacements of the photometric from the gravitational nucleus may produce spurious non-gravitational accelerations.

The physical characteristics of comets vary with their orbits and with their age. New comets on their first near solar passage from the Oort cloud are extremely active. The activity falls statistically with increasing age. This sequence must represent a corresponding sequence or layering of structure from the surface of a new comet inwards and is described qualitatively in this paper.

The excessive activity of new comets is ascribed to cumulative cosmic-ray damage that activates the outer few hundred gm cm-2 from the surface. The total energy input in 4.6 x 109 yr reaches 50,000 cal gm-1 near the surface so that both crystalline structures and molecules are severely damaged if not completely destroyed. Annealing at T - 10 K must be very small. Hence significant exothermic energy in the form of defects, vacancies and radicals is added to produce the extraordinary activity observed in new comets.

Other aspects and problems of cometary activity are discussed.

Convection is the main energy transport mechanism in brown dwarf atmospheres. The overshoot of ascending bubbles affects the upper and cooler region where dust formation can occur. In order to understand the observed presence of dust, the formation of grains and their gravitational settling must be balanced by up-mixing of condensible elements via convective overshoot. Otherwise, brown dwarf atmospheres would be completely dust-free (Woitke & Helling 2004).

We report on two recent XMM-Newton observations of Brown Dwarfs in the Pleiades cluster and in the field aiming to constrain the age dependence of X-ray emission from substellar objects.

We have searched for magnetic signatures in A-type supergiants. The obtained magnetic values for seven of these stars are presented here.

I have been invited by the organisers to provide an overall perspective on the subject of this Symposium. Necessarily, this will be a subjective impression of topics in which there has been quite remarkable progress since the last General Assembly of the IAU, and which are of the greatest interest for the whole of science. In preparing a review of such an enormous field, one veers between optimism and pessimism about the successes and problems which have arisen. I hope to steer a realistic course between these extremes. Fortunately, there are many experts participating in this Symposium who will be able to neutralise my personal biases and provide authoritative opinions on all the topics I will cover.