We examined two “magnetic antibuoyancy” effects: i) turbulent diamagnetism and ii) magnetic advection caused by vertical inhomogeneity of plasma density in the SCZ (the $\nabla \rho$ effect). The Sun's rotation which yields the $\nabla \rho$ effect with new properties was taken into account. It is shown that at high latitudes antibuoyancy effects block the magnetic fields in the deep layers of the SCZ. However, in the region located near-equator the $\nabla \rho$ effect, modified by rotation, causes the upward magnetic advection. So it can facilitate penetration of strong magnetic fields to solar surface where they then arise in the “royal zone” as the sunspots.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The complicated and intricate time-dependent behavior of the magnetic field of $\beta$ Lyrae from 1980 to 2004 is discussed.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We describe a study of the compositional properties of heliospheric ICME ejecta within the context of solar CME observations. In this study, we examine CME-ICME pairs with an associated flare. For each of these pairs several in situ quantities are averaged over the event and compared with flare magnitude. We find that Mg/O, He/O, and He/H are clearly correlated with flare magnitude suggesting that larger flares provide the CMEs with increased access to the low corona. We also find flare magnitude is positively correlated with velocity and negatively correlated with density, indicating that CMEs which are related to large flares are more likely to experience over-expansion during their propagation to 1 AU.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

High $S/N$ high-resolution spectroscopic observations of seven bright well-known $\lambda$ Bootis stars: HD 31295, HD 91130, HD 110411, HD 125162, HD 183324, HD 192640, and HD 221756 are presented. Sharp absorption details observed in the bottoms of the Na-D lines in HD 192640 and HD 221756 do not show any radial velocity changes with an accuracy up to $1\,{\rm km\,s}^{-1}$. They are of interstellar origin. Manifestations of non-radial pulsation reported earlier in literature are observed both in the Na-D and the ${\rm H}\alpha$ line profiles. The Inglis-Teller formula was used to evaluate the electron density in the upper atmospheric layers ($\tau \sim 0.1$). The values obtained for $\log{N_e}$ are typical for normal A stars with similar effective temperatures and spectral classes.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A detailed analysis of the spectrum of I Zw 1 shows that the Narrow Line Region, unlike that of most Seyfert 1 galaxies, is a very low excitation region dominated by both permitted and forbidden Fe II lines. The physical conditions in this region are discussed.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

From all the transient events identified in interplanetary space by in-situ measurements, Magnetic Clouds (MCs) are among the most intriguing ones. They are a special kind of Interplanetary Coronal Mass Ejections (ICMEs), characterized by a well-defined magnetic field configuration. We use a list of 40 MCs detected by Ulysses to study bidirectional flows of protons in the $\sim$0.5 MeV energy range. Solar wind ions are also analysed in order to compare cloud to non-cloud ICMEs.

The enhancement in freezing-in temperatures inside the clouds, obtained with data from the SWICS instrument, provides insights into processes occurring early during the ejection of the material and represents a complementary tool to differentiate cloud from non-cloud ICMEs. At higher energies, directional information for protons obtained with the EPAC instrument allows a comparison with previous results concerning bidirectional suprathermal electrons. The findings are qualitatively comparable. Apparently, the portion of bidirectional flows inside magnetic clouds is neither heavily dependent on distance from the Sun nor on parameters obtained from a flux rope model.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We have imaged $\sim 1$ deg$^{2}$ in the V-band in the direction of the Hercules cluster (Abell 2151). The data are used to compute, for the first time, the luminosity function (LF) of galaxies in the cluster down to the dwarf regime (M$_{lim}$$\sim -13.85$ ). The global LF is well described by a Schechter function (Schechter 1976) with best-fit parameters $\alpha = -1.30 \pm 0.06$ and M$_V^* = -21.25 \pm 0.25$. The radial dependence of the LF has also been studied, finding that it turns out to be almost constant within the errors even further away than the virial radius. Given the presence of significant substructure within the cluster, we have analized the LFs in different regions. While the LFs of the two subclusters present are consistent with each other and with the global one, the southernmost one exhibits a somewhat steeper faint-end slope.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

At the footpoints of loops spanning a site of flux emergence, earlier investigated in the papers by Solanki et al. (2003) and Lagg et al. (2004), we find large redshifts in the He 1083 nm line coexisting with an almost unshifted component. The speed associated with these redshifts reaches values as high as 40 km/s. We interpret these downflows in the context of several models: the free-fall downflow of matter along vertical field lines (Schmidt et al. 2000), the redshift by downward propagating acoustic waves (Hansteen 1993) and the motion of condensation regions to either side of loop footpoints (Müller et al. 2003). We present the temporal evolution of these redshifts and reconstruct the magnetic field vector in these regions for both the redshifted and the unshifted atmospheric component.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

An analytical method is used to model a magnetic field distribution in the vicinity of a large interplanetary or solar flux rope. The field is a sum of the pre-existing one and an additional current-free part. An example using real data is shown.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We report the results of combined Chandra, HST/STIS, and FUSE observations of the intrinsic absorption in the Seyfert 1 galaxy NGC 4151. Our previous studies revealed an unusually large column of outflowing gas, very close to the nucleus, which responds rapidly to changes in the ionizing continuum due to its high density. With the latest observations, we have discovered evidence that the large absorbing column consists of individual high and low ionization components, and that the column density of the latter has decreased due to bulk motion across our line-of-sight. The Chandra spectra have revealed the signature of both very high ionization lines such as H-like and He-like Si, and inner-shell lines from low ionization species which may be associated with the UV absorbers. With the FUSE observations, we have detected lines from less abundant elements, which have permitted us to constrain the physical conditions and covering factors of the UV absorbers. These results indicate a complex and heterogeneous absorbing system, the extreme properties of which are likely the result of a relatively large viewing angle with respect to the accretion-disk axis.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We have undertaken an imaging survey of low surface brightness dwarf galaxies in nearby groups with the main goal of studying the faint-end of the galaxy luminosity function at z $\sim 0$. Here we describe the results on the search for LSB dwarf galaxies in two compact groups: HCG44 and HCG68. Our study explores the surface brightness, sizes, magnitudes and colours of these candidate dwarf galaxies. The selection criteria were their central surface brightness, scale factors and diameters at the limiting isophote of 26 R mag$/"^{2}$. We estimate the faint end of the luminosity function of galaxies through Monte Carlo simulations. The observed magnitude distribution of the candidate dwarf galaxies in the groups (down to $M_{R} \sim - 13$) is compatible with a Schechter function with a slope $\alpha \sim -1.2$.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present a new method of phenomenologically modelling light curves of variable stars using Principal Component Analysis techniques that provide a realistic description of the variability with a minimum of free parameters. Examples of this method are demonstrated for the magnetic CP stars HD 90044 and HD 125248.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the results of Fourier and wavelet time series analysis for the high-cadence observations of an active region NOAA 8011, obtained with the Nobeyama Radioheliograph (NoRH) at the wavelength of 1.76 cm on 17.01.1997. Oscillations in brightness are found to be present with periods in the range from minutes to hours. The relationship between the active region oscillations in the microwave total intensity (I) and circular polarization (V) emission and changes of the magnetic field, deduced from the high-resolution magnetograms from MDI/SoHO, is investigated. We concentrate on the identification of different oscillation modes, the temporal behavior of the oscillations and the spatial distribution of different oscillating frequencies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We investigate the environmental dependence of galaxy properties in the local universe based on the data of the Sloan Digital Sky Survey. We focus on how star formation and morphology of galaxies correlate with luminosity, local environment, and global environment. We find that galaxy properties abruptly change at a critical local density of $\log \Sigma_{\rm crit}\sim 0.4\ {\rm galaxies}\ h_{75}^{2}\ \rm Mpc^{-2}$. The ‘break’ at the critical density is found only for faint galaxies ($M^*_r+1 < M_r < M^*_r+2$). Bright galaxies ($M_r < M^*_r+1$) show no break. That is, the star formation-density and the morphology-density relations depend on galaxy luminosity. Next, we focus on global environment, i.e., richness of galaxy groups and clusters. Most galaxies are not forming stars in groups as poor as $\sigma\sim200\rm\ km\ s^{-1}$. This fact suggests that environmental mechanisms that are effective only in rich clusters, such as ram-pressure stripping of cold gas and harassment, have not played a major role in suppressing galaxy star formation. Our results may suggest that evolution of bright galaxies is not strongly related to galaxy systems such as groups and clusters. On the other hand, evolution of faint galaxies may have a close connection.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The paper describes our approach to simulations of real interplanetary events, consisting of four steps: (i) determination of background solar wind, (ii) parameterization of a model flux rope, (iii) launching it into the solar wind, and (iv) calculating its propagation and evolution.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Near-infrared spectroscopic observations in the range 0.8-2.4μm are used to study the kinematics and excitation mechanisms of Molecular Hydrogen and [FeII] lines in a sample of AGNs. The width of H2 lines is narrower than [FeII] lines, therefore they do not originate from the same parcel of gas. The molecular emission is found to be purely thermal but with heating processes which vary among the objects. A clear correlation between H2/Brγ and [FeII] 1.257μm/Paβ is found for our sample objects supplemented with data from the literature. The correlation of these line ratios is a useful diagnostic tool in the NIR to separate emitting line objects by their level of nuclear activity.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Elemental abundance analysis are derived for the Mercury-Manganese stars HR 4817 (B8 II/III) and $\mu$ Lep (B9 IV) using CCD recorded exposures obtained at the EBASIM echelle spectrograph at the 2.1-m CASLEO (Complejo Astronómico El Leoncito) telescope in Argentina. The spectra coverage is 390-900 nm. The results are compared with previous analyses made with spectra taken using the REOSC echelle spectrograph at CASLEO, the coudé feed telescope at Kitt Peak National Observatory, and/or with the Dominion Astrophysical Observatory coudé spectrograph. As these new spectra go farther into the red and have better resolution than those obtained with the REOSC, we could make better abundance determinations.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present results of a study of the morphology and evolution of active regions using solar acoustic holography. These include acoustic signatures of large far-side active regions and their relationship to near-side activity indices a half rotation before and after the farside image, and the direct comparison of near-side acoustic signatures with the standard activity indicators, not only in their own right but also to calibrate the farside acoustic signature.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the values of CN and Mg overabundances with respect to Fe, for early-type galaxies in 8 clusters over a range of richness and morphology. Spectra were taken from the Sloan Digital Sky Survey (SDSS) DR1 spectroscopic database, and from WHT and CAHA observations. Abundances were derived from absorption lines and single burst population models, by comparing galaxy spectra with appropriately broadened synthetic model spectra. We find robust correlations between [Mg/CN] and [CN/Fe] abundance ratios and cluster X-ray luminosity. No correlation was observed for [Mg/Fe]. We also see a clear trend with the richness and morphology of the clusters. This behavior is interpreted given varying formation timescales for CN, Mg and Fe, combined with a different star formation history in early-type galaxies as a function of their environment. This result supports the scenario in which early-type galaxies in more massive clusters are assembled on shorter timescales than those galaxies within less massive clusters.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

VLT and NTT spectra are used to examine the nuclear and extended coronal line emission in a sample of well-known Seyfert 1 and 2 galaxies. The excellent spatial resolution obtained with VLT allowed us to map [Si VI] 1.963μm and [Si VII] 2.48μm on scales of up to 20 pc. Coronal line emission, extended to distances of ∼102 pc, is detected in some of the lines analyzed, particularly in [Fe X] 6374Å, [Fe XI] 7891Å, and [Si VII] 2.48μm. Most coronal lines are strongly asymmetric towards the blue and broader than low-ionization lines. This result is particularly important for Circinus, where previous observations have failed to detect larger widths for high-ionization lines. Photoionization models are used to investigate the physical conditions and continuum luminosities necessary to produced the observed coronal emission. We found that an ionization parameter U>0.10 is necessary to reproduce the observations, although the clouds should be located at a distance <30 pc from the central engine.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html