We argue that the outburst of CI Cam (XTE J0421+560), probably containing a black hole, was caused by the thermal instability of the accretion disk. Applying the model of King & Ritter (1998), we obtain a realistic disk mass and radius. The differences from soft X-ray transients belonging to the low-mass X-ray binaries can be explained if the disk in CI Cam heats up an extended envelope and/or a strong jet is formed. We resolve several spectral components in the optical colors in quiescence after the outburst; they vary in a complicated way during a possible 1350 d cycle.

We find indications that the variations of the source of the optical light can be related to those of the X-ray source in quiescence. The accretion disk seems to refill at present. Nowadays, only non-periodic intra-night optical (∼0.02 mag) fluctuations are present. As regards the absence of coherent changes in the optical band, we point out the similarities in the situation of CI Cam and the microquasar LS5039/RX J1826–1450.

As pristine condensates from a large number of stars, pre-solar grains provide unique information on the sources, types, compositions and processing histories of dust in the Galaxy. However, their promise remains largely unfulfilled. Here we discuss some of the astrophysical problems for which pre-solar grains might provide important insights and constraints in coming years.

Basic properties of equipotential surfaces in test perfect fluid tori with uniform distribution of the specific angular momentum orbiting KdS black holes are summarized. The central mass-densities of adiabatic non-relativistic tori, for which the approximation of test fluid is adequate, are given and compared with the typical densities of Giant Molecular Clouds.

Spectropolarimetric methods used at the Sayan Solar Observatory for measuring magnetic field strengths are described. The spectropolarimeter consists of a polarization splitter and a ferroelectric liquid crystal (FLC) modulator, allowing for several longitudinal H measurement modes. The report discusses advantages and disadvantages of modulation-based and modulationless measurements using ordinary slow CCD cameras. In some cases combined variants appear to be preferable.

We report our study of X-ray cluster morphology using a sample of 101 clusters of galaxies at redshift z~0.05-1 taken from the Chandra archive.

We use UVES spectroscopy of PB 6 to study the variation of its physical conditions as a function of position including: temperature, density, chemical composition and velocity. We present preliminary results from this work. In particular we want to find the relevance of the contribution of the wind from the central star to the chemical composition of the nebula; we find that the contamination due to the WR wind is small.

I review efforts to determine the ages and chemical compositions of early-type galaxies from their integrated spectra. After reviewing the history of integrated light analyses, we consider how reliably the light-weighted mean ages and chemical compositions of galaxies can be extracted from current state-of-the-art population synthesis modelling and observational data. Particular attention is given to assessing the best strategies for pursuing integrated spectrum analysis, both from observational and modelling standpoints. Finally, we consider efforts to move beyond light-weighted mean ages and metallicities, specifically, to constrain star formation histories with multiple episodes of star formation.

Turbulence has a significant influence on the chemistry of molecular clouds. Do molecular abundances alter if we use superdiffusion instead of simple diffusion? After our first simplified calculations it seems there is a notable difference.

We present and discuss the Hα (λ = 6563Å) observations of the contact (W UMa type) binaries AE Phoenicis and YY Eridani, obtained in 1989, 1990 and 1995 with the CAT/CES telescope of the Southern European Observatory (ESO). In particular, we compare the intrinsic equivalent widths of both components with the NextGen theoretical models and the saturation limit. We find that the average Hα equivalent widths are close to the saturation border and that the primary components have excess Hα-emission, indicating enhanced chromospheric activity. This is compatible with both theoretical and observational suggestions that the primary is the more magnetically active component and is filled with (mostly unresolvable) dark spots and associated chromospheric plages.

We use multi-colour data of the gravitational lensing cluster Abell 1835 to search for high-z candidates (Richard et al. 2006) and extremely red galaxies.

Applying a colour criteria of R-K ≥ 5.6 we have selected 12 EROs, of which 10(9) have no R(I)-band detection. Two of these sources posses multiple detections in the ACS z850 band, possibly gravitationally bound objects.

Using the method of Pozzetti and Mannucci (2000) to classify an ERO either as evolved elliptical or dusty starburst, we find that two thirds of all objects have colours assigned to evolved ellipticals. One of the remaining 4 sources is the known sub-mm source SMMJ14009+0252.

The spectral energy distributions of sources with no optical detection show strong similarities to the SED of the high-z object of Mobasher et al. (2005), i.e. a degeneracy between a low- and high-z solution. However, for objects we accept the low-z solution as the better fit.

A detailed analyses of the colour properties and spectral energy distribution will be published in two forthcoming papers (Schaerer et al., Hempel et al.).

The greatest discoveries in astronomy have accompanied technological innovations that have opened new windows of the electromagnetic spectrum. One of the last poorly explored regions lies at wavelengths longer than 3 m (100 MHz) to the ionospheric cutoff around 30 m (10 MHz). In the past, variations in the ionosphere have limited ground-based instruments to small (< 5 km) apertures and hence relatively coarse angular resolution and low sensitivity.

Stellar winds from O and WR stars transfer large amounts of mechanical energy and momentum into the interstellar medium. They sweep up and compress the interstellar material, creating interstellar bubbles. These structures are detected as optical ring nebulae, as thermal radio continuum sources, as infrared shells, as neutral gas voids and expanding shells in the HI line emission distribution, and as molecular shells.

From VLT FORS1 on-band, off-band imaging of the dIrr NGC3109 we have identified about 13 PN candidates. According to our criteria for PN candidate selection, most of the candidates reported by Richer & McCall (1992) are in fact compact HII regions. Further multi-object VLT FORS1 spectroscopy has confirmed the PN nature of at least 6 candidates. All but one of the PNe analyzed are low excitation nebulae, showing no He II emission lines. For several PNe and HII regions, we derived chemical abundances based on electron temperatures measured from the [O III] 4363/5007 line ratios. Preliminary results show that PNe present log(O/H)+12 in the range from 7.7 to 8.4, while in HII regions this quantity spreads in a much narrower range from 7.6 to 7.8. Thus, the ISM in NGC 3109 seems chemically homogeneous.

In Galactic microquasars with double-peak kHz quasi-periodic oscillations (QPOs), the ratio of the two frequencies is 3:2. This supports the suggestion that double-peak kHz QPOs are due to a non-linear resonance between two modes of accretion disk oscillations. For the microquasars with known mass, we briefly compare the black hole spin estimates based on the orbital resonance model with the recently reported spin predictions obtained by fitting the spectral continua. Results of these two approaches are not in good agreement. We stress that if the spectral fit estimates are accurate and can be taken as referential (which is still questionable), the disagreement between the predicted and referential values would represent a rather generic problem for any relativistic QPO model, as no spin influence would appear in the observed 1/M scaling of the QPO frequencies. The epicyclic frequencies relevant in these models are often considered to be equal to those of a test particle motion. However modifications of the frequencies due to disc pressure or other non-geodesic effects may play an important role, and the inaccuracy introduced in the spin estimates by the test particle approximation could be crucial.

Long-slit spectra have been obtained with the Keck telescope for a sample of 11 early-type galaxies covering a range in luminosity. Rotation velocity and velocity dispersions, together with 20 Lick line-strength gradients have been measured to two effective radius. We transform line-strength gradients into age, metallicity and α/Fe. Galaxies show very shallow age gradients, strong metallicity gradients, and both positive and negative α/Fe gradients, which cannot be explained with simple outside-in scenarios of galaxy formation. We explore the correlation of the gradients with other global parameters of the galaxies, finding different behaviour for the two families of galaxies, luminous (boxy, core inner profile) and less luminous (disky, cuspy inner profile) galaxies.

We propose an action-based f(R) modification of Einstein's gravity which admits of a modified Schwarzschild-deSitter metric. In the weak field limit this amounts to adding a small logarithmic correction to the Newtonian potential. A test star moving in such a spacetime acquires a constant asymptotic speed at large distances. This speed turns out to be proportional to the fourth root of the mass of the central body in compliance with the Tully-Fisher relation. A variance of MOND's gravity emerges as an inevitable consequence of the proposed formalism.

We present a brief description of new complex of space telescopes and spectrographs, TESIS, which will be placed aboard the CORONAS-PHOTON satellite. The complex is intended for high-resolution imaging observation of full Sun in the coronal spectral lines and in the spectral lines of the solar transition region. TESIS will be launched at the end of 2007 – early of 2008. About 25 % of the daily TESIS images will be free for use and for downloading from the TESIS data center that is planned to open 2 months before the TESIS launching at http://www.tesis.lebedev.ru

We present preliminary conclusions derived from the analysis of a sample of galactic PNe with [WC]-type central stars (WCPNe) observed with Spitzer/IRS. We report the detection of double-dust (C-rich and O-rich) chemistry in all stars in the sample for which a good S/N spectrum was obtained. Our observations reveal that the simultaneous presence of oxygen and carbon-rich dust features in the infrared spectra of WCPNe is not restricted to late/cool [WC]-type stars, as previously suggested in the literature, but it is found to be a common feature associated to all WCPNe. In particular, mixed chemistry is observed in at least seven early/hot WCPNe in the sample. Various scenarios are proposed to interpret the results obtained in the framework of the chemical evolution of PNe.

A194 and A1060 are studied for the nature of point source properties. X-ray to optical luminosity ratios (Lx/Lb) are evaluated for selected galaxies. Cumulative log(N)-log(S) and intrinsic luminosity functions are applied for a comparative evaluation with Lockman Hole. 46 and 32 X-ray point sources are detected by EPIC-PN, for A194 and A1060 respectively. The XLF space density shows significant excess compared to field and local group space density. The result is interpreted as the fueling of AGNs as they enter the ICM from outskirts of the clusters and dimming of the very bright AGNs as they further proceed into cluster core.

We present preliminary results for six spiral galaxies from a sample of 25, where we have used the method developed by González & Graham (1996) to search for and analyze azimuthal color gradients across spiral arms. The six galaxies analyzed here are NGC 1703 (SBrb), NGC 3001 (SABrsbc), NGC 3059 (SBrsbc), NGC 3513 (SBrsc), NGC 4593 (RSBrsb), and NGC 4603 (SAsc).

NGC 1703: We found one azimuthal color gradient in NGC 1703. Star formation was traced with the reddening free parameter Q, and the dust lane was located with the (g – J) color. This gradient lies at a distance of 1.45 kpc from the center of the galaxy. In order to get some physical parameters of the star formation processes that are taking place in the spiral arms of the galaxies in our sample, we compared the observed Q profiles with the stellar population synthesis models of Bruzual & Charlot (2003). The fitted Q model is shown in figure 1. If one assumes that stars form in the site of the shock, and that they age as they move away from this birthsite, then distance from the dust lane (at constant radius) parameterizes stellar age. In fact, stretching the model Q to the fit the data fixes the ratio between the distance and the age of the stellar population. If, in addition, the rotational velocity is known, it is possible to find the angular velocity of the spiral pattern. The spiral pattern speeds derived from the gradients (under the assumption that star formation is triggered by the density wave) yield theoretical resonance positions that are coincident with the observed spiral end points, in 3 out of 6 spirals. It would be hard to avoid the conclusion that disk dynamics and star formation are fundamentally related in these objects.