In the past 10 years, observations from space have generated a genuine revolution in our understanding of the Sun. Its interior is now “observed” down to a few % of the solar radius, its internal dynamics, its rotation and the large scale flows that are found to exist under its “surface” are studied continuously for over nearly a complete solar cycle. The mechanisms that underlie solar activity are better understood as well as their effects on the heliosphere and on the planets of the Solar System, in particular on the Earth.

However, there are still opened questions that deserve to be answered through a new generation of space instruments, requiring the best experts in the world and an extended fleet of space missions that no single country is able today to undertake alone. In this context, the International Living with a Star programme is a key element that must be pursued with full strength. At the same time, new missions that are not part of that programme should begin to be studied. They will provide the ultimate resolution and accuracy that are necessary to go a step further in the knowledge of the Sun and of its effects on our planet.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We summarize of more than 25 years of research with the three filter, intermediate-band, $\Delta a$ photometric system. It investigates the flux depression at $\lambda 5200$ found in magnetic chemically peculiar (CP) objects. Starting with photoelectric measurements it has steadily developed introducing new and more efficient filters as well as the modern CCD technique. So far more than twenty papers were devoted to searching for new CP stars in our Milky Way up to distances of 5000 pc and even in the Large Magellanic Cloud. In the latter, the first extragalactic CP stars were detected. In addition, we have presented theoretical isochrones and synthetic colors from the latest available stellar atmospheres. The theoretical predictions agree very well with observations allowing not only to determine the reddening and age of open clusters from our photometry but also to investigate the flux depression at $\lambda 5200$ in more detail. As an outlook, we present a new approach to search for chemically peculiar horizontal branch stars in globular clusters and to detect stellar variability of various objects observed during our photometric observations.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

I present preliminary results and discussion from a K-band imaging study of the host galaxies of samples of ULIRGs and IR-bright QSOs, designed to match in terms of their FIR luminosities and redshift distributions. Large K-band bulges are found to be present in all of the quasars, with the majority of the ULIRGs being best-fit by a disc. Despite the apparent difference, a significant overlap exists between the two populations in terms of their nuclear luminosity. A significant unresolved nuclear component is present in all of the objects, and this is found to correlate with the luminosity of the K-band host across the sample.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

I discuss in this contribution the accretion and ejection processes occurring in solar-type young stars. Understanding these two important processes, and their link, is one of the major issues in star formation. The magnetic field is thought to play a central role in both extracting the angular momentum from the disk and directing the accretion flow onto the star. I will focus on the well studied T Tauri stars, optically-revealed pre-main sequence stars with ages 1-10 Myrs and mass $\simeq$ 0.5 M$_{\odot}$. In the first part of this contribution, I present the current paradigm for magnetically channeled accretion, where the stellar magnetic field truncates the disk and directs the accretion flow and discuss recent observations, which indicate that this process is non-axisymmetric and time-dependent. I then turn to the study of the supersonic collimated jets observed in young stars. Magneto-hydrodynamic processes are the most likely driving mechanism. I present the main steady and non-steady outflow models, as well as constraints brought by recent high-resolution studies. I finally discuss the origin of time variability in jets.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Modern solar telescope design in the EUV to x-ray range is now capable of producing large images in multiple channels at rapid cadences, with high spatial and temperature resolution. We discuss reconstruction of differential emission measures for solar coronal plasma using two state-of-the-art instruments: the X-Ray Telescope on Solar-B, and the Atmospheric Imaging Assembly on the Solar Dynamics Observatory. We discuss the relative merits of iteration and direct inversion methods for determining DEM($T$). We also consider strategies for automating and visualizing DEM maps, given the high data rates that these instruments will produce. We touch on the scientific potential of high-cadence, spatially resolved DEM data products.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We introduce our project that investigates the kinematic properties of early–type galaxies in 6 distant poor clusters at $z\approx0.25$. This study represents a continuation of our efforts to understand galaxy evolution in low-density environments. Higher–resolution MOSCA spectra have been obtained at the Calar Alto 3.5-m telescope with which we can measure absorption line strengths and velocity dispersions. In conjunction with our HST/F702W images of all the clusters, we are able to construct the Fundamental Plane of ellipticals and S0 galaxies in poor clusters at a look-back time of $\approx3$ Gyr. For galaxies outside the HST field, we concentrate our analysis on the Mg–$\sigma$ and Faber–Jackson relations. With the line strength diagrams age/metallicity distributions can be derived in densities between the field and rich cluster environments. Comparing with our rich clusters at the same cosmic epochs, the dependence of galaxy formation models on the local environment can be tested more quantitatively.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

High $S/N$, high resolution CCD spectra of 10 Am binaries with different orbital elements, rotation and atmospheric parameters obtained with the 2-m telescope of NAO Rozhen (Bulgaria) were analyzed. We carried out preliminary abundance analyses of these stars and studied the possible dependences of abundance anomalies and [Ca/Fe] on their values of effective temperature, $v\sin i$, orbital period, and eccentricity. There are weak trends of [Ca/Fe] increasing with $v\sin i$ and decreasing with eccentricity and orbital period. [Ca] seems to be increasing with effective temperature, and [Fe] decreasing with $v\sin i$ and increasing with eccentricity. However we need to study more stars to confirm and disentangle the possible trends.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We use the photoionization code MAPPINGS Ic to model optical emission-line ratios of the extended emission-line regions of 24 Seyfert galaxies. Although most line ratios can be reproduced by varying the ionization parameter, gas density and/or the shape of the ionizing continuum, the ratio [NII]λλ6548,84/[OII]λ3727 can only be reproduced if we allow for a range of oxygen abundances of 0.5≤ (O/H)/(O/H)$_{\odot} \leq$ 3 for the whole sample. We propose a calibration to obtain (O/H) in terms of [NII]/[OII]. Also, in order to reproduce the emission-line spectra beyond 2 kpc from the nucleus, we had to introduce the contribution from hot stars to the ionizing spectra. We conclude that this is due to an increasing contribution of HII regions with distance from the nucleus to the emission-line regions.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the analysis of intrinsic UV absorption in the Seyfert 1 galaxy Mrk 279, observed simultaneously with HST/STIS (40 ks) and FUSE (92 ks). To derive the absorption covering factors and ionic column densities, we employ an algorithm based on minimizing errors in simultaneous fits to multiple lines. This technique allows for the treatment of more complex (and physically realistic) scenarios of the absorption-emission geometry, giving more accurate measurements and unique geometrical constraints on the mass outflow.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The possibility of a quite high Li abundance in the Ap stars was first raised by Wallerstein & Merchant (1965). Since then many studies investigated the problem of Li. The more recent observations in the lithium region indicate that in some Ap stars the $\lambda 6708$ feature is variable and this variability can be explained by the existence of Li rich spots on the stellar surface. Atomic data for the Ce II$\lambda 6708.099$ were released by the D.R.E.A.M. database in 2002. The line was used to identify the prominent suspected Li-feature in post AGB stars and might as well be responsible for the absorption feature in Ap stars. Recent studies have mentioned this possibility, but it has yet to be investigated in more detail. Other physical phenomena, such as the occurrence of a partial Paschen-Back effect in the presence of magnetic fields, as well as possible hyperfine structure splitting of some Rare Earth transitions, must be taken into account to provide correct line identifications in the wavelength region around the Li-doublet at $\lambda 6708$. We discuss a possible strategy to clarify the presence of Li in Ap stars.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The very active RS CVn-type star UX Ari was observed using high-resolution echelle spectrograph attached to the 2.16m telescope of Xinglong station in Nov.-Dec. 2001 and Dec. 2002. By means of synthetic spectral subtraction method, the information about chromospheric activity of the system was obtained through several chromospheric activity indicators HeI D$_3$, NaI D$_1$D$_2$, H$_{\alpha}$, and CaII IRT lines. Based on the analysis for these activity indicators, we found that the chromospheric activity of UX Ari showed obvious orbital modulation phenomenon, and the favorite active longitudes were around the quadratures of the binary system. During the two observing runs, hot plage and very strong optical flare events were detected, which were always happened around the favorite active longitudes of the system. Moreover, they were linked with the photospheric starspots in spatial structure, and appeared just above the main starspots.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We explore possible correlations between the light profile shapes of early-type galaxies, as parameterized by the Sérsic index $n$, and relevant stellar population parameters, which were obtained from spectra of extremely high signal–to–noise and stellar population models that provide an age indicator that is virtually free of the effects of metallicity. We do not find any robust correlation between $n$ and mean age or metallicity. However, we find evidence for a strong positive correlation between $n$ and [Mg/Fe] abundance ratio. We speculate that early-type galaxies settle up their structure on short time-scales in agreement with those imposed by their [Mg/Fe] ratios, suggesting that the global structure was already at place at high $z$.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

This paper reviews some recent results obtained from multi-wavelength studies that extend from white light to radio. Special emphasis is given to radio observations, which can be used to determine emission mechanisms and to trace electron propagation paths and plasma motions. Multi-wavelength comparisons have been found to be essential when analysing flare- and CME-related eruptions, but significant results have also been obtained in ‘quiet’ Sun studies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the first results of the CP star observations in the spectral regions of the Li I lines at $\lambda 6708$ and $\lambda 6104$ obtained with the 6-m BTA telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We explore the stellar halo of the Milky Way to search for fossil signatures of past mergers. We use the Beers et al. (2000) catalog of non-kinematically selected metal poor stars in the solar neighborhood to select subsets of halo stars within 1-2 kpc of the Sun. Motivated by the results of high resolution CDM simulations, we look for substructure in the kinematics of the fastest stars. When a two-point velocity correlation function is applied to these subsets, statistical evidence of substructure is found. This appears to be due to a small moving group with dynamical properties similar to the stellar “stream” previously discovered by Helmi et al. (1999).To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The continuum energy distributions of R127 and R110 in the outburst phase are fitted by use of a optically envelope model. Both stars show two peaks in the continuum energy distributions in which one lies in the short-wavelength range (near 1250Å) and the other in the optical band. We suggest that the fluxes in the UV and optical bands may have different origins: the UV flux comes from the central star and the optical flux comes from the expanded optically envelope. We construct such a model for LBVs with the use of two LTE atmosphere models with different temperatures, and find it to be in satisfactory agreement with the observed spectral energy distributions of R127 and R110.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present near-IR, diffraction limited imaging of the nucleus of NGC 1068 obtained with NAOS-CONICA at VLT. These observations provide an accute view on the distribution of hot dust in the vicinity of the central source, at a 0.1” resolution. The use of a new type of coronagraph allowed us to detect and identify new structures at K, to calculate more accurate color indices, and derive the state of the dust in this very complex morphology. We also used deconvolution on images aquired in other bands to get an accute view of these structures.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Three approaches for coronal magnetic loops on the Sun and the stars are considered: (i) loop as MHD-resonator, (ii) loop as electric circuit, (iii) loop as a magnetic mirror trap.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We explore the region of influence of a galaxy cluster using numerical simulations of cold dark matter halos. Many of the observed galaxies in a cluster are expected to be infalling for the first time. Half of the halos at distances of one to two virial radii today have previously orbited through the cluster, most of them have even passed through the dense inner regions of the cluster. Some halos at distances of up to three times the virial radius have also passed through the cluster core. We do not find a significant “infall age” versus present day position for substructures and the scatter at a given position is very large. This relation may be much more significant if we could resolve the physically overmerged galaxies in the central region.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We investigate temporal fluctuations in the H$\alpha$ emission profiles of the RS CVn system HR 1099 from a monitoring using the MuSiCoS spectropolarimeter (Observatoire du Pic du Midi, France) in 2001, between December 01 and December 18. Part of the observed emission fluctuations is consistent with rotational modulation, which we interpret as the spectral signature of a dense and complex prominence system trapped in the magnetosphere of HR 1099 and forced to co-rotate with the binary system. The distribution of emitting material is mapped by means of Doppler tomography. We discuss the evolution of prominences over the observing window.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html