Convection is one of the most intricate processes studied in stellar astrophysics and has challenged both theorists and observers since the beginnings of astrophysics. But during the last two decades observational data of unprecedented resolution and accuracy have been collected in solar and stellar research which permit a new look at the field. An enormous increase of computer speed now permits solving more complete model equations with more accurate numerical approximations. Modelling and theoretical understanding of convection, however, are lagging behind observational progress and are still wanting.

As a background to the contributions to this session on convection, I first provide an overview on its basic physics and its observational evidence. I point out why astrophysicists have a general interest in improvements of our understanding of stellar convection and then focus on convection in A-stars with their unique combination of convection zones. I summarise how this richness of different manifestations can arise in A-stars, such as convection zones near the surface and in the core, several on top of each other, or some of them depleted by diffusion processes, suppressed by or even creating magnetic fields, suspected to create a chromosphere in some of them, or influenced by binaries, to name just a few. In the last part I will present a few recent results on modelling of convection in A-stars.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The $\bf {E \times B}$ drift allows plasma to move through the magnetic field lines and may contribute to various motions inside the Sun (e.g. to explain the adverse gradient of differential rotation in the equatorial zone), at its surface and in the corona. Here we treat an example: using a given azimuthal angular frequency $\omega$(r, $\theta$), rather arbitrary, and the corresponding exact solution for $\bf{B}$, we obtain $\bf{E}$ and the drift velocity. The latter is comparable with the original velocity, but has components in all directionsTo search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The detection of very high energy emission in blazars with the new generation of TeV telescopes rises the question of the origin of this emission and its relation to that at other wavelengths. In this work we present contemporaneous optical and X-ray observations of two bright and close southern hemisphere blazars: PKS 2005-489 and PKS 2155-304, the latter detected at TeV energies. The SED between radio and X-rays is discussed and compared with that of other TeV blazars.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In this work, we review the analytical and semi-analytical tools introduced to deal with resonant proper elements and their applications to the Trojan asteroids, the numerical computation of synthetic proper elements for resonant and non resonant asteroids, and the introduction of proper elements for planet crossing asteroids. We discuss the applications and accuracy of these methods and present some comparisons between them.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Scalar-tensor (ST) theories of gravity are the best motivated alternative to general relativity (GR), arising in every high-energy theory attempting to unify all the fundamental interactions. Furthermore, accomodating an arbitrary number of scalar fields, ST theories yield to cosmological scenarios with a dynamical realization of the dark energy. Solar-System experiments and binary-pulsars observations are compatible with very small departures from GR on the local universe ($z\simeq 0$); on cosmological scales, big-bang nucleosynthesis and cosmic microwave background (CMB) observables can admit larger deviations from the predictions of GR. Weak lensing could provide a test for ST theories of gravity on intermediate scales. Based on a code developed to study ST theories on CMB observables, we implemented a plug-in code to compute the convergence power spectrum and some 2-points statistics. Preliminary results using a simple model of ST theory are presented. This study is aimed to constraint classes of ST models.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Using multi-spectral data, we estimate plasma parameters in the post-eruptive arcade observed on October 22, 2001 at 100 Mm above the limb: the temperature is 6 MK and the plasma density is $(5-9) \cdot 10^9$ cm$^{-3}$. We state a problem of the long-term equilibrium of the hot top of the arcade high in the corona: either the magnetic field surrounding the arcade well exceeds that one extrapolated in the potential approximation, or $\beta > 1$ both inside and outside the arcade. A downflow observed in soft X-rays can contribute to the equilibrium.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Practical measurement of the passage of time requires the notion of a repeating phenomenon. The Earth's rotation has traditionally fulfilled this requirement. To cope with the impracticality of making precise measures of the Sun's hour angle or altitude, particularly in uncooperative weather conditions, various devices have been employed, but all have been calibrated with respect to astronomical phenomena related to the Earth's rotation, or to its orbital motion with respect to the Sun. Modern requirements for timing precision coupled with an increased understanding of the variability of the Earth's rotational speed are likely to bring about a change in the traditional relationship between precise timekeeping and astronomy. The historical background of this relationship and the current definitions are reviewed to show the development of timekeeping capabilities and the growing need for precise timekeeping. Possible future developments are outlined along with their advantages and disadvantages.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present results from 547 optical galaxy redshifts obtained in the region of Horologium-Reticulum (HR) using the 6dF (six-degree field) multi-fiber spectrograph on the United Kingdom Schmidt Telescope. Concentrating upon the inter-cluster regions of the HR Supercluster (HRS), we derive three primary results from our 6dF observations. First, the HRS covers a redshift range from at least 16000 to 22500 kms−1. Second, these HRS galaxies exhibit an overall gradient with increasing redshift along a spatial axis of SE-NW with high statistical probability. Third, along the best-fit line from the spatial-redshift linear regression, HRS galaxies comprising the redshift trend are distinctly split into a high- and low-redshift component. Finally, comparisons of the spatial-redshift distribution are made between the HRS and the Shapley supercluster.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Convection and turbulence in stellar atmospheres have a significant effect on the emergent flux from A-type stars. The recent theoretical advancements in convection modelling have proven to be a challenge to the observers to obtain measurements with sufficient precision and accuracy to permit discrimination between the various predictions.

A discussion of the current observational techniques used to evaluate the various convection theories is presented. These include filter photometry, spectrophotometry, hydrogen lines, and metal lines. The results from these techniques are given, along with the successes and limitations.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Results gathered to anchor the MBH−σ∗ relation raise concerns in the methods of measuring of σ∗ used for the original slope determinations. We present these preliminary results to demonstrate the problem and briefly outline where the discrepancies arise. IFS is a valuable tool in addressing this area and will allow us to remove systematics before tightening the MBH−σ∗ relation and end the “aperture arguments”.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In this proceeding we present the method and results of the search for galaxy groups or clusters in the vicinity of the line-of-sight towards lensed quasars.We have studied a sample of ten quasars, using deep ESO/VLT FORS1 and ISAAC images, as well as archive HST/WFPC2 and NiCMOS data. We find that there is most probably a galaxy group towards CTQ 414, HE 0230-2130, B 1359+154, H 1413+117, SBS 1520+530 and HE 2149-2745, with masses $\leq$4~10$^{14}$M$_\odot$h$^{-1}$. Considering its photometric redshift, the galaxy group discovered in the field around HE 1104-1805 is associated with the quasar rather than with the lensing potential. We also conclude that the pair LBQS 1429-0053-A and LBQS 1429-0053-B is a genuine binary quasar rather than a lensed quasar.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The paper presents a review of the recent contributions and open questions concerning the families of asteroids. Due to the availability of very large catalogues (synthetic and analytical proper elements of the asteroids and large observational surveys of their spectra) and to the introduction of non gravitational forces in their determination, the concept of static family has disappeared, to be replaced by this of dynamical families. The proper elements are not constant anymore but are ageing on very long timescales. The size distributions of the populations of asteroids, in and out the families, their ages, the ejection velocities of the fragments after an impact, have been reconsidered by several teams of research, with this new approach. Parallel numerical simulations of collisions and fragmentations of bodies have showed that most of the asteroids are likely rubble piles or agglomerates than monolithic blocks. The methods of classification have been refined and combine, in their newest versions, the dynamics and the observations, working now on 5 dimensional space instead of 3. A series of sub families of the large well-known families have been recently identified, using catalogues with more than 100 000 asteroids (the cluster Karin for example).To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Conventionally coronal mass ejections (CMEs) are categorized into flare-associated and filament-associated types. Since there are also many CMEs of the overlapping type, we classify CMEs into three types in order to compare their characteristics. It is found that the three types of CMEs have quite similar distributions of apparent speeds, with small difference in the average speeds.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The first observations containing evidence of a measurable stellar parallax were made by Thomas Henderson at the Cape of Good Hope in 1832/33. Although his response to Manuel Johnson's discovery in early 1833, that $\alpha$ Cen has a large proper motion, was to intensify observations for his remaining month at the Cape, Henderson apparently saw no urgency to reduce his observations. Instead he laboured through more routine matters, producing a catalogue of declinations of southern stars, improvements of refraction tables, and work on the solar and lunar parallaxes. It was Bessel's announcement of a determination of the parallax of 61 Cyg that finally stirred Henderson into action in late 1838.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The radial surfaces of constant angular frequency may be connected with the upper rest latitude of the filament bands (or boundaries of large-scale unipolar magnetic regions) and with the separation of the sunspot region and the polar region (polar faculae, etc.). The equator-ward evolution of the rest latitudes observed since cycle 12 may be a forebode of a deep minimum.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present a dynamical analysis of the central $\sim$ 1.3 square degrees of the galaxy cluster Abell 1367, based on 272 redshift (of which 118 are new measurements). From the analysis of the 146 confirmed cluster members Abell 1367 appears as a young cluster currently forming at the intersection of two filaments.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The atmosphere of Venus was discovered for the first time by the Russian scientist Mikhail V. Lomonosov at the St Petersburg Observatory in 1761. Lomonosov detected the refraction of solar rays while observing the transit of the planet across the disk of the Sun. From these observations he correctly inferred that only the presence of refraction in a sufficiently thick atmosphere could explain the appearance of a light (‘fire’) ring around the night disk of Venus during the initial phase of transit, on the side opposite from the direction of motion. Lomonosov described this phenomenon, which carries his name, as the appearance ‘of a hair-thin luminescence’, which encircled a portion of the planet's disk that had not yet contacted the solar disk. He also observed a bulge set up at the edge of the Sun during the egress phase of the Venus transit. ‘This bears witness to nothing less than the refraction of solar rays in the Venusian atmosphere’, he wrote. This paper is based on the original Lomonosov publications and describes historical approaches to the study involving procedure, drawings, and implications.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The oscillations in solar daily soft X-rays (SXR) have been analyzed for 22$^{nd}$ and 23$^d$ solar cycles. The SXR in the 1–8Å passband have been recorded by the GOES-6,8 satellites from January 1986 to April 2003 year. For 22$^{nd}$ cycle the revealed periodicities 24, 43, 54, 65 and 73 days coincide with the 23$^d$ cycle ones within data uncertainty (1 day) and their values may be explained by the differential rotation of the solar chromosphere and corona.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Gravity is the most important force to affect the motion of bodies in the Solar system. At small sizes, however, additional forces must be taken into account to explain fine details of their translational and rotational motion, as well as parameters of their populations. This is because the strength of the non-gravitational perturbations typically increases as $\simeq 1/D$ toward small sizes $D$. The principal perturbation acting on macroscopic main-belt bodies (sizes up to several kilometers for timescales of about billion years) is due to the anisotropic thermal re-radiation of the absorbed sunlight. In orbital dynamics this is known as the Yarkovsky effect, while in rotational dynamics the same physical phenomenon is called the YORP (Yarkovsky-O'Keefe-Radzievskii-Paddack) effect. We review the main observational implications of the Yarkovsky/YORP effects as understood and evidenced today.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present preliminary results from a wide-field spectroscopic survey of two galaxy clusters at $z=0.4$, separated by $\lt$10 $h^{-1}$ Mpc on the sky. Both clusters are similarly optically rich, have velocity dispersions $\sim 700$ km s$^{-1}$, but differ in X-ray luminosity by a factor of $\sim$20.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html