It was found that filaments observed in EUV could be much more extended than in H$\alpha$. These extended dark structures visible in EUV are named EUV filaments. Their parts seen only in EUV (not observable in H$\alpha$ because of low opacity at the H$\alpha$ wavelength) are called EUV-filament extensions (or simply EUV extensions). For the EUV filament observed by SoHO on 15 October 1999 as northern polar crown filament, only a few small dark structures were seen in H$\alpha$. This suggests that the mass of the EUV extension is larger than, or at least comparable with, the mass of the parts of the filament observed in H$\alpha$. In our previous work we determined the 3D structure of the EUV extension of this EUV filament. In this paper we present the determinations of mass and average density of this EUV extension. For better density estimates we interpret the hydrogen Lyman lines observed by SUMER using non-LTE radiative transfer code. From the best fitting of Lyman lines we obtained a reasonable model of the EUV extension with low gas pressure, temperatures from 2$\times10^4$ K to $10^5$ K and with extended prominence-corona transition regions.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

During the final production stages of the above article, the images of Figures 4 and 5 were transposed. The correct layout, with legends are reproduced below.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We discuss how the energy feedback from active galactic nuclei and quasars is essential in explaining the observed X-ray luminosities and entropy levels of the intracluster and intragroup medium.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We describe a semi-analytic model for the X-ray emitting gas in clusters and groups in which the gas is preheated before halo formation. The model relies on physically sound prescriptions for the formation and evolution of halo structure. For a gas temperature gradient corresponding to a polytropic index of 1.2 and an energy injection of 0.6 keV per gas particle, this model successfully reproduces the observed correlations between gas luminosity, gas temperature and halo mass. We use the model to investigate the detailed entropy structure of groups and clusters of galaxies and compare the results with the observational data.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A brief review is given on the progress made in the study of the catastrophe of coronal magnetic flux ropes with implication in coronal mass ejections (CMEs). Relevant studies have been so far limited to 2.5-D cases, with a flux rope levitating in the corona, either parallel to the photosphere in Cartesian geometry or encircling the Sun like a torus in spherical geometry. The equilibrium properties of the system depend on the features of the flux rope and the surrounding background state. Under certain circumstances, the flux rope exhibits a catastrophic behavior, namely, the rope loses equilibrium and erupts upward upon an infinitesimal variation of any control parameter associated with the background state or the flux rope. The magnetic energy of the system right at the catastrophic point may exceed the corresponding open field energy so that after the background field is opened up by the erupting flux rope, a certain amount of magnetic free energy is left for the heating and acceleration of coronal plasma against gravity. The flux rope model has been used to reveal the common features of CMEs and to simulate typical CME events, proving to be a promising mechanism for the initiation of CMEs. Incidentally, the Aly conjecture on the maximum magnetic energy of force-free fields places a serious constraint on 2.5-D flux models. Nevertheless, current sheets must form during a catastrophe on the Alfvén timescale, and magnetic reconnection across the newly formed current sheets may contribute to circumventing such a constraint. In this sense, the catastrophe simply plays a role of driver for the fast magnetic reconnection, and a combination of them is thus responsible for the initiation of CMEs.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We analyze some of the tens of active regions (AR) each supposed to produce at least one solar flare detected in Gamma- and hard X–rays by the SONG–M spectrometer on board the CORONAS–F satellite. Of special interest is the AR NOAA 9601, which gave rise to the solar flare at 14:30 UT on September 5, 2001 with up to 4 MeV intensity in Gamma and of M6.0 class only in soft X–rays. We examine 1D radio scans of NOAA 9601, taken with the RATAN–600 in Stokes I and V at a set of wavelengths from 1.92 to 10 cm and radio maps taken with the Solar Siberian Radio Telescope (SSRT) at 5.2 cm. The type of this microwave source is classified among the other sources. The some prediction evidences of such type sources are listed.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the results of a spectrophotometric study of star forming regions in HII galaxies. In particular, we find that, besides their “blobbiness”, HII galaxies are quite homogenous in their chemical properties, though we do see important fluctuations in some physical properties (e.g. extinction).To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

WADE: For Padovani: Is it straigthforward to implement our own catalogs into the Virtual Observatory (VO)?

PADOVANI: Very easy. There is a button to load your own data, and that includes a list of sources. The table has to contain one record per line, each field separated by a TAB. Once loaded, your own catalog can be overlayed on any image and cross-correlated with any catalog in the public domain.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The Fraunhofer spectra were used to study the physical condition variations in the photospheric layers in the course of a bright solar flare. The observations involve both the impulsive and main phases of the flare. The spectral lines are formed in the photosphere at the interval 12–500 km. The modelling was made by fitting the observed and calculated line profiles using the SIR program. The models represent the distributions of temperature, gas density, line-of-sight velocities, etc. on the height. They show some inhomogeneities of these physical parameters at various photospheric levels. Their significant deviations from the VAL-F model may be seen in the course of the flare. The largest heating of the high and middle photospheric levels take place close to two X-ray maxima. At the final flare stage the photosphere is disturbed appreciably while the spectral data testify to the flaring process fading in the chromosphere. This may be an evidence of a disturbance propagation from the upper atmospheric levels to the low ones in the impulsive and main phases.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Some highlights of Symposium 224 on “The A-Star Puzzle” are reviewed and transcribed from the author's ad hoc oral presentation on the final day of the meeting. Articles referred to are all contained in this volume, hence there are no figures or references. Topics include theory and observations of normal A stars, HgMn, Am, and Ap stars, $\lambda$ Boo stars, magnetic fields, rotation, convection, pulsations, supergiant stars, and observational methods including polarimetry, spectroscopy, and photometry.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We used the near-infrared [Fe II] emission line signature of shock-heating to detect supernova remnants (SNRs) in nearby starburst galaxies. The near-IR narrow-band imaging program has led to the detection of SNR candidates in NGC 1569 and NGC 5253, both host to super-star clusters. A spatially extended component to the [Fe II] line emission dominates the integrated [Fe II] luminosity in the two galaxies. Despite the starburst environment, the [Fe II] luminosity of the individual SNRs is two orders of magnitude lower than the luminosities observed for SNRs in M82. We find that the density and the structure of the interstellar medium is a more important factor than the starburst nature of a galaxy in determining the average [Fe II] luminosity of a SNR. The observations suggest that a significant fraction of the ISM in NGC 1569 and NGC 5253 is under the influence of SNRs. This does not appear to be the case in M82 where the impact of the SNRs is limited to high density knots.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Two–and–half–dimensional reconnection is examined for a compressible plasma: Exact solution of jump relations in the system of discontinuities is used to investigate how the outflowing jet and the conditions in the intermediate region depend on the characteristics of the inflow. The most significant implications concerning large-scale eruptive phenomena of solar atmosphere are presented.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Using high-resolution non radiative SPH simulations we study the scaling laws of galaxy clusters. In particular, we analyze the relations existing between total mass, gas temperature, X-ray luminosity and dark matter velocity dispersion. Our aim is to understand how these scaling laws depend on numerical, statistical and physical parameters, in order to model and thus reduce potential systematical uncertainties. The simulations were performed by the GADGET code in a $\Lambda CDM$ cosmology, applying resimulation techniques; their mass resolution ranges between $2 \times 10^9$ and $6.8 \times 10^9 h^{-1}M_{\odot}$ for dark matter particles and between $3 \times 10^8$ and $7 \times 10^8 h^{-1}M_{\odot}$ for gas particles.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Using the results of an extended set of high-resolution non-radiative hydrodynamic simulations of galaxy clusters we obtain simple analytic formulae for the dark matter and hot gas distribution, in the spherical approximation.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the results of a new stellar population synthesis code which mixes both evolutionary and empirical population synthesis techniques. The code decomposes a given galaxy spectrum into a base of high resolution spectra from the recent evolutionary synthesis models of Bruzual & Charlot (2003). The main novelty is that now we synthesize the whole Fλ spectrum, rather than a handful of absorption lines and colors.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A coronal current-free field model, which applies the asymptotic condition of no field at infinity and the boundary condition on the solar surface specified, is presented. Some Applications of the method to practical solar events indicate that the extrapolated global magnetic field structures effectively demonstrate the case for the disk signature of the radio CME and the evolution of the radio sources during the CME/flare processes.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Opacity sampling with ATLAS12, the stellar atmosphere code developed by R.L. Kurucz, cannot always be carried out with the desired frequency or depth resolution because of the limited computing power of even the fastest monoprocessors. There are also known problems of portability which make it difficult to run ATLAS12 with various compilers on different operating systems.

We first created a Fortran77 version that can be compiled using the g77 compiler, a useful feature for astronomers having no access to VMS compatible Fortran compilers. As a further step, ATLAS12 was successfully ported to Ada95, an object-oriented parallel language. ATLAS12 is now platform independent, split up in modules and running in parallel on multi-processor machines. Any limitations as to the maximum number of depth and frequency grid-points and the number of lines that can be treated have been pushed far beyond what is possible with the original version.

We intend to incorporate the continuous opacity routines of ATLAS12 in our new CAMAS code for magnetic atmospheres (but also in the existing COSSAM and CARAT codes) to be able to compare our results with Kurucz's de facto stellar atmosphere standard.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The preflare plage spectra were obtained with the ATsU-26 solar telescope mounted at the Peak Terskol. The spectra were acquired from 1 h to 20 min before the flare onset. The most prominent peculiarity of all the observed events are the tilted $H_{\alpha}$-emission details which appear less than 40 min before the flare. This result may testify to spiral structure of the ascending $H_{\alpha}$ loops. The ascending velocities in the chromosphere attain more than 10 km/s. Two crossing $H_{\alpha}$ loops were observed to interact before 1n flare. As a result of their interaction, the redistribution of velocities occurs in the both chromosphere and photosphere. This can be a consequence of the preflare reconnection at the lower atmospheric layers. As the flare onset approaches the ascend of photospheric material start to dominate. The preflare line-of-sight velocities exceed considerably those in the neighbouring unperturbed regions.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A short review on abundance determinations of A and F dwarfs in the Hyades is presented. The spectroscopy was carried out with AURELIE, a monorder spectrograph at the Observatoire de Haute Provence (France) at a resolving power close to 40000 with Signal-to-Noise ratios varying from 100 to 300. Abundances of 11 chemical elements have been derived by using Takeda's (1995) procedure.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We study the global effects of the clouds-SN shock wave interactions on the mixing of the gas in Starburst galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html