Atomic clocks are an outstanding tool for the experimental verification of general relativity and more generally for fundamental astronomy (VLBI, pulsar timing, navigation, etc). Recent years have seen a rapid improvement in the performance of such clocks, promising new improved tests of relativity, in particular onboard terrestrial and interplanetary space missions. We present the scientific motivations of such tests taking the ACES Salomon et al. and SAGAS Wolf et al. (2009) projects as particular examples.

The globular cluster luminosity function distribution shows a peak at MV ≈ −7.5 mag. There are some indications that the kinematic parameters are correlated with luminosity. In particular, Alfaro et al. (2001) have studied the properties of the Galactic globular cluster system and they found a correlation between spatial-velocity component and globular cluster absolute magnitude. The authors assumed that the globular clusters can be separated into two groups. The first is composed of globular clusters with MV < −7.5 mag and moving preferentially towards the north Galactic pole, while the faintest globular clusters, composing the second group, move towards the Galactic disk. We have selected a sample of globular clusters using the same criteria as Alfaro et al. (2001) and have checked that this apparent relation indeed exists. Nevertheless, we decided to investigate whether it could be a fortuitous relation or an intrinsic property by checking its validity for eight different epochs at past and future times. The orbital parameters for the globular clusters at these eight epochs were found by orbital integration using a typical Galactic potential. We show that this relation between the vertical velocity component and the absolute magnitude among globular clusters is not coherent with time and the velocity distribution does not support the hypothesis of Alfaro et al. for the existence of two dynamical groups of globular clusters.

Information about positions and velocities of stars that will be gained in the era of GAIA is crucial for determining dynamical structure in our Galaxy. The distribution function of all component objects in our Galaxy is fundamental for describing its dynamics. However, only the distribution function of observable stars is obtained from space astrometry observations, and it is therefore necessary to develop theoretical studies of how to construct the distribution function of all matter including dark matter and unobservable stars using astrometric data of observable stars. This procedure falls into three categories.

We observed several H ii regions in the dwarf irregular galaxy NGC 6822 using the infrared spectrograph on the Spitzer Space Telescope. Our aim is twofold: first, to examine the neon to sulfur abundance ratio in order to determine how much it may vary and whether or not, it is fairly ‘universal’; second, to discriminate and test the predicted ionizing spectral energy distribution between various stellar atmosphere models by comparing with our derivation of the ratio of fractional ionizations involving neon and sulfur. This work extends our previous similar studies of H ii regions in M83 and M33 to lower metallicities.

The research carried out so far on the identification of constellations in the Inka civilisation is far from exhaustive, as there is both a great difficulty in obtaining the data and much heterogeneity in the information gathered. A brief presentation is given here.

Atmospheric parameters and Li abundances have been determined for 162 stars observed at high resolution, high signal to noise ratio with the ELODIE echelle spectrograph (OHP, France). Among them, about 70 stars are active stars with a large fraction of BY Dra type stars. For all stars, rotational velocities were obtained with a calibration of the cross-correlation function, effective temperatures by the line depth ratio method, surface gravities by the parallaxe method and by the ionization balance of iron. The frequency of stars with observed lithium is significantly higher in active stars than in non active stars. Among active stars, no clear correlation has been found between different indicators of activity for our sample stars, but some correlation of an index R′H K and vsini is observed.

In this paper, I present the results on large-scale evolution of density turbulence of solar wind in the inner heliosphere during 1985–2009. At a given distance from the Sun, the density turbulence is maximum around the maximum phase of the solar cycle and it reduces to ~70%, near the minimum phase. However, in the current minimum of solar activity, the level of turbulence has gradually decreased, starting from the year 2005, to the present level of ~30%. These results suggest that the source of solar wind changes globally, with the important implication that the supply of mass and energy from the Sun to the interplanetary space has significantly reduced in the present low level of activity.

A comparison is carried out among the star formation histories of early-type galaxies in fossil groups, clusters and low density environments. Although they show similar evolutionary histories, a significant fraction of the fossils are younger than their counterparts, suggesting that they can be precursors of the isolated ETG galaxies.

Observational data show that the correlation between the masses of supermassive black holes MBH and galaxy bulge masses Mbulge follows a nearly linear trend, and that the correlation is strongest with the bulge rather than the total stellar mass Mgal. With increasing redshift, the ratio Γ=MBH/Mbulge relative to z = 0 also seems to be larger for MBH≳108.5M⊙. This study looks more closely at statistics to see what effect it has on creating, and observing, the MBH–Mbulge correlation. It is possible to show that if galaxy merging statistics can drive the correlation, minor mergers are responsible for causing a convergence to linearity most evident at high masses, whereas major mergers have a central limit convergence that more strongly reduces the scatter. This statistical reasoning is agnostic about galaxy morphology. Therefore, combining statistical prediction (more major mergers ⟹ tighter correlation) with observations (bulges = tightest correlation), would lead one to conclude that more major mergers (throughout an entire merger tree, not just the primary branch) give rise to more prominent bulges. Lastly, with regard to controversial findings that Γ increases with redshift, this study shows why the luminosity function (LF) bias argument, taken correctly at face value, actually strengthens, rather than weakens, the findings. However, correcting for LF bias is unwarranted because the BH mass scale for quasars is bootstrapped to the MBH–σ* correlation in normal galaxies at z = 0, and quasar–quasar comparisons are mostly internally consistent. In Monte-Carlo simulations, high Γ galaxies are indeed present: they are statistical outliers (i.e., “under-merged”) that take longer to converge to linearity via minor mergers. Additional evidence that the galaxies are undermassive at z≳2 for their MBH is that the quasar hosts are very compact for their expected mass.

The corotation radius in a spiral galaxy is the place where the spiral pattern speed has the same velocity of the rotation curve. By compiling results coming from the literature for 20 spiral galaxies we verified a strong correlation between the radius of the minima or inflections of the metallicity distribution and the corotation radius.

We present a new method for constructing equilibrium phase models for stellar systems. Applications of the iterative method include both modelling of observational data and the construction of initial condition for N-body simulations.

This paper reviews the history of Chinese astronomy from the perspective of the rôle it played in establishing the Heaven-Man relationship in ancient China, which was politically and morally significant, and which in turn gave Chinese astronomy its most important characteristics.

Solar activity and its consequences for the interplanetary space are governing and perturbing the Earth's magnetosphere. The response of the terrestrial magnetosphere displayed as geomagnetic disturbances is measured by several geomagnetic indices. This paper analyses the geomagnetic variability during the ascendant phases of the last four solar cycles (nos. 20-23) under the influence of the high speed solar wind. The ascendant phase of a solar cycle is a proper interval of the irrespective cycle during which the influences of the solar cycles adjacent to it (the precedent and the following ones) are not present. The correlation between the geomagnetic indices and the high speed stream intensity during the analysed intervals was examined. Lomb-Scargle method of spectral analysis was applied on the solar wind velocity series during the ascendant phases.

The discovery of Dark Energy and the fact that only about 5% of the mass of the universe can be explained on the basis of the current laws of physics have led to a serious impasse. Based on past history, physics might indeed be on the verge of major discoveries; but the challenge is enormous. The way to tackle it is twofold. On one side, scientists try to perform large scale direct observations and measurements – mostly from space. On the other, they multiply their efforts to put to the most stringent tests ever the physical theories underlying the current view of the physical world, from the very small to the very large. On the extremely small scale very exciting results are expected from one of the most impressive experiments in the history of mankind: the Large Hadron Collider. On the very large scale, the universe is dominated by gravity and the present impasse undoubtedly calls for more powerful tests of General Relativity – the best theory of gravity to date. Experiments testing the Weak Equivalence Principle, on which General Relativity ultimately lies, have the strongest probing power of them all; a breakthrough in sensitivity is possible with the “Galileo Galilei” (GG) satellite experiment to fly in low Earth orbit.

Double bars might be the key mechanisms to transport gas to the very central regions of galaxies, so double-barred galaxies are key objects to better understand the galaxy formation and evolution scenarios. In order to disentangle the role of double bars in the galaxy build up, we are performing a whole kinematical and stellar population analysis of these objects from high S/N spectroscopic data.

Lithium abundance measurements in dwarf stars in open clusters are of crucial importance for our understanding of the mixing mechanism and have allowed us to achieve important conclusions on the matter. However, in order to further our understanding of what drives lithium depletion, lithium abundance measurements have to be coupled with accurate temperature determinations, which are best achieved when the analysis of iron lines is employed. Effective temperature estimations from photometry, on the contrary, can be affected by errors as large as several hundred kelvins due to uncertain open cluster reddening, especially when studying old open clusters, which tend to be more distant. We present lithium abundance in 12 dwarfs belonging to 4 open clusters at about 1 or 2 Gyr. The stellar effective temperatures, along with the other parameters, were estimated from the analysis of about 60 Fe I lines and 10 Fe II. Even though the few datapoints call for caution, we notice that stars in the open cluster IC 4651 seem to present a steep decline with temperature below 6000 K.

RCW 34 is a special star-forming region with a few stars showing an infrared excess, but seems as if it has an uncommon abundance in T Tauri stars. This possibility was confirmed by (i) clustering of classical T Tauri (CTT) stars in the two-color diagram, (ii) clustering of pre-main-sequence stars in the color–magnitude diagram, as well as (iii) the significant clustering at dimensions larger than the image-frame size, indicated by the second ‘bump’ in the two-point correlation analysis. A possible explanation for the above features could be the existence of an underlying wide CTT cluster with a smaller cluster centered around the massive star. The Ks-band luminosity function (α = 0.31) of RCW 34 shows that it is indeed a region of low stellar masses with an age of about of 1 Myr. Spectroscopic confirmation of such an underlying T Tauri cluster is necessary before any definite conclusions can be reached.

We present results from infrared spectroscopic projects that aim to test the relation between the mass of a black hole MBH and the velocity dispersion of the stars in its host-galaxy bulge. We demonstrate that near-infrared, high-resolution spectroscopy assisted by adaptive optics is key in populating the high-luminosity end of the relation. We show that the velocity dispersions of mid-infrared, high-ionization lines originating from gas in the narrow-line region of the active galactic nucleus follow the same relation. This result provides a way of inferring MBH estimates for the cosmologically significant population of obscured, type 2 AGN that can be applicable to data from spectrographs on next-generation infrared telescopes.

We constructed a program that allows one to use simultaneously and interactively photometric and astrometric stellar data (proper motion) to analyse color–color and color–magnitude diagrams. With this program, we are able to determine, based on photometric membership, the distance and age as well as the mean proper motion and radial velocity of several open clusters which had very uncertain parameters in previous analyses.