We have studied the host-galaxy morphologies of narrow- and broad-line Seyfert 1 galaxies (NLS1s and BLS1s) based on broad-band optical images from the Hubble Space Telescope archives. We find that large-scale stellar bars, spanning 1–10 kpc from the nucleus, are much more common in NLS1s than BLS1s. Furthermore, the fraction of NLS1 spirals that have bars increases with decreasing full-width at half-maximum (FWHM) of the broad component of Hβ. This suggests a link between the large-scale bars, which can support high fueling rates to the inner kpc, and the high mass-accretion rates associated with the supermassive black holes in NLS1s. A preliminary examination of the inner (<1 kpc) dust morphologies has revealed no significant differences between NLS1s and BLS1s, except that we confirm the previous finding that galaxies with large-scale bars have a much higher frequency of “grand design” nuclear dust spirals.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

I briefly report on the work conducted to probe the gravitational potential of active and non-active disk galaxies using gas and stellar kinematics.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Explosive events and blinkers are two observational classes of transients seen on the quiet Sun and an investigation of the significance of and relationship between such events may be critical for understanding basic processes at work in the solar atmosphere. Our analysis showed that blinkers and explosive events are independent phenomena which have to be explained separately.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In an effort to elevate to higher grounds our understanding on the impact of the formation and evolution of bars in the formation and evolution of galaxies, we have developed a diagnostic tool to distinguish between recently formed and evolved bars. Our method was applied in the study of a sample of 14 galaxies and revealed that, apparently, AGN activity tends to appear in galaxies which have young bars rather than evolved bars. This suggests that the time scale for the fueling of AGN by bars is short, and may help to explain, for instance, why there is not a clear correlation between the presence of bars and AGN in galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We summarize the results of our studies of CME-associated EUV dimmings and coronal waves by ‘derotated’ fixed-difference SOHO/EIT heliograms at 195Å with 12-min intervals and at 171, 195, 284, 304Å with intervals of 6 or 12 hours.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The NUGA project is a high-resolution (0.5″−1″) CO survey of low luminosity AGN including the full sequence of activity types (Seyferts, LINERs and transition objects). NUGA aims to systematically study the different mechanisms for gas fueling of AGNs in the Local Universe. In this paper we discuss the latest results of this recently completed survey, which now includes newly acquired subarcsec resolution observations for all targets of the sample. The large variety of circumnuclear disk morphologies found in NUGA galaxies (m = 1, m = 2 and stochastic instabilities) is a challenging result that urges the refinement of current dynamical models. In this paper we report on new results obtained in 4 study cases for NUGA: NGC 4826, NGC 7217, NGC 4579 and NGC 6951.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

On the base of the interferometric observations during the total solar eclipse on 11 August 1999 magnetic field strength in a coronal volume at the height of 10$^5$ km above the solar limb has been evaluated using an indirect method. A cold coronal emission (CCE), seen in the lines of $H_{\alpha}$ and K CaII, existed there. The conclusion is made that the magnetic field strength in this bulk, before the investigated CCE-region formed, was about 100-200 G.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We performed the study of a solar flare of GOES class X1.0 which occurred on 2002 August 21, peak time 05:34 UT. A new method was applied for temperature determination of the plasma seen in TRACE images. This method makes use of the detailed knowledge of the TRACE point spread function (PSF) function. Substantial dependence of TRACE PSF on wavelength allows for determination of temperature from a single TRACE image even in these portions of the image which are saturated. We also determined the average temperature of this flare from the soft X-ray spectra measured by RESIK Bragg spectrometer aboard CORONAS-F satellite. The results obtained from TARCE and RESIK data are compared.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Nuclear spirals can provide a wealth of information about the nuclear potential in disc galaxies. They form naturally as a gas response to non-axisymmetry in the gravitational potential, even if the degree of this asymmetry is very small. Linear wave theory well describes weak nuclear spirals, but stronger asymmetries in the potential induce waves beyond the linear regime, which appear as spiral shocks. If a central massive black hole (MBH) is present, spiral shocks can extend all the way to its immediate vicinity, and generate gas inflow up to 0.03 M$_{\odot}\,$ yr−1. This coincides with the accretion rates needed to power local Active Galactic Nuclei.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We identify 175 Seyfert galaxies from the Southern Sky Redshift Survey – SSRS2. We use the entire SSRS2 catalog to investigate the correlation between the presence of AGN with host environment. The AGN phenomenon is more strongly correlated with the internal host properties than with the external environment. In particular, we find that Seyferts reside in more luminous galaxies, and are twice as frequent in barred galaxies and systems showing signs of advanced merger condition, when compared to a control sample.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The radio and multi-wavelength signature of coronal loop interaction is discussed in the event on November 28, 1998 with X-class flares and CMEs, observed by Nobeyama Radioheliograph (NoRH), YOHKOH/SXT/HXT, SOHO/EIT/LASCO, and Chinese radio spectrometers (2.6-3.8 GHz). The fluctuations at rising phase with bi-directional drift rates may show the signature of magnetic reconnection caused by loop interaction. There are two or three peaks in radio time profiles and spectra, which show that two or three flares are triggered in the process of loop interaction. The 17 GHz sources are composed of three parts with different time profiles and polarization feature. The formation of twisted loops in post-flare phase may indicate the start time of the CMEs in this event.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The comparison of the polarization presence in Ellerman bombs or moustaches and the active region arch structure was carried out. In the most cases of the polarization, interpreted as impact polarization, were detected in that regions where the bright small loops were observed. On the contrary, when a significant polarization wasn't detected the scanning during observation was carried out nearby the large loops.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Atomic gas in the central kiloparsec of young radio galaxies is quite prevalent, as revealed by 21cm H I absorption line observations using the WSRT. The column depths are anti-correlated with the linear sizes of the radio sources, but VLBI reveals that sometimes the neutral hydrogen is situated in a disk or torus on parsec or sub-kiloparsec scales around the central engine, while in other cases the H I is probably associated with star-forming regions along the jets. NGC 1052 is a nearby example, in which, next to some isolated clouds along the jets, there appears to be an atomic and molecular torus with a radius of a few parsecs, but with a central hole of about 0.5 pc, in which the gas is mostly ionised.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

RESIK Bragg spectrometer aboard CORONAS-F solar observatory collected spectra of hundreds of solar flares in the unique spectral range between 3.3 Å and 6.1 Å. The instrument's absolute and relative calibrations are now finished which allows for the first time to interpret the observations in terms of the differential emission measure (DEM) distribution. With known DEM shape it is possible to derive and study in detail flaring plasma composition and energy balance. Here we report results of using an improved Maximum Likelihood iterative algorithm (Withbroe-Sylwester) for determination of the DEM distributions for 7 January 2003 flare at 23:30 UT. The study is based on the absolute flux values observed in a number of strong H- and He-like transitions of K xviii, Ar xviii, Ar xvii, S xvi, S xv, Si xiv and Si xiii ions. In this respect, we use line and continuum X-ray emissivities as provided by CHIANTI package from SolarSoft.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We have analyzed the frequency and properties of the nuclear activity in two samples of galaxies, with and without circumnuclear rings and spirals (CNRs). We discuss the relevance of the results in the framework of the AGN feeding processes and some results are: (i) bright companion galaxies seem not to be important for the appearance of CNRs, therefore these would be more related to intrinsic properties of the host galaxies or to minor merger processes; (ii) the proportion of strong bars in AGN galaxies with a CNR is higher than the expected rate of strongly barred AGN galaxies from the sample of Ho and co-workers; (iii) the incidence of Seyfert activity coeval with CNRs is clearly larger than the expected rate from the morphological distribution of the host galaxies; (iv) the rate of Sy 2 to Sy 1 in galaxies with CNRs is larger than the expected proportion for galaxies without CNRs; this proportion would be in the opposite sense as expected from the geometric paradigm of the classical unified model for AGNs, but supports a scenario where Sy 2 activity is linked to circumnuclear star formation.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Solar flare on 26 June 1999 was accompanied by radio bursts giving an indirect evidence of accelerated superthermal particle beams. It is generally believed that this effect can stimulate an impact linear polarization in Balmer series spectral lines. The flare was observed simultaneously by the Ondřejov Multichannel Flare Spectrograph (MFS) and by the Large Solar Vacuum Telescope (LSVT) using the polarization optics in the H$\alpha$ line. Spectropolarimetric data obtained by the two instruments are analyzed, however no substantial linear polarization was detected. Both spectral and auxiliary data, including radio and X-ray observations are analyzed to discuss possible reasons of the lack of linear polarization.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

From hydrodynamical simulations for the response of gaseous disks to imposed potentials, including those of a bar and supermassive black hole (SMBH), we found that the morphology of nuclear features developed by gas flows driven by the bar depends strongly on the sound speed of gas and the mass of SMBH which governs the potential shape in the central kiloparsec. Thus, nuclear features seem to provide a promising diagnostic for the inner dynamics of spiral galaxies. Specifically, a tightly wound grand-design nuclear spiral that winds more than 2π indicates the presence of an SMBH which is massive enough to remove the IILR.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

During the last decades many authors have concentrated their efforts on understanding what are the most efficient mechanisms to feed an AGN. Several solutions have been proposed, as the presence of circumnuclear star clusters, nuclear bars/disks/spirals, and the interaction between galaxies, in form of close encounters and mergers. Here we present new results about an isolated, intermediate-type Seyfert galaxy, Mrk315. The analysis of broad- and narrow-band images, and integral field spectra revealed a spiral-like structure hidden under the E/S0 morphology of the galaxy, and confirmed the presence of a nuclear jet-like feature, forming a sort of very extended “hook”. Moreover, our data confirmed the supposed nature of the already known knot, located at 2” from the active nucleus, as a secondary nucleus, residual of a minor merger bewteen the galaxy and a small nucleated companion.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A preflare situation in a loop structure for stability to the development of plasma waves at the chromosphere part of a current circuit of a loop is investigated. We consider the situation when plasma has the spatial gradients of the density and temperature. In accordance with Heyvarts-Priest-Rust theory such a preflare situation would typically exist when the amplitude of weak electric field in the circuit of an “old” loop in an active region begins to increase as “new” magnetic flux emerges from under the photosphere (Heyvaerts, Priest & Rust (1977)).To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The description of two major flares detected by SONG spectrometer on board the CORONAS-F mission during famous period of solar activity in October- November 2003 and their comparison with soft X-ray measured by GOES-12 is given.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html