We present multi-object spectroscopic observations from FORS1 mounted at the VLT for 5 clusters detected in the ESO Imaging Survey. Together with the results for three other clusters presented previously, we confirm a total of 6 out of 8 clusters with estimated redshift $z_{MF}\geq0.6$. The spectroscopic redshifts are in good agreement with the estimated ones.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We integrated the orbital evolution of 30,000 Jupiter-family comets, 1300 resonant asteroids, and 7000 asteroidal, trans-Neptunian, and cometary dust particles. For initial orbital elements of bodies close to those of Comets 2P, 10P, 44P, and 113P, a few objects got Earth-crossing orbits with semi-major axes $a<2$ AU and moved in such orbits for more than 1 Myr (up to tens or even hundreds of Myrs). Three objects (from 2P and 10P runs) even got inner-Earth orbits (with aphelion distance $Q<0.983$ AU) and Aten orbits for Myrs. Our results show that the trans-Neptunian belt can provide a significant portion of near-Earth objects, or the number of trans-Neptunian objects migrating inside the solar system can be smaller than it was earlier considered, or most of 1-km former trans-Neptunian objects that had got near-Earth object orbits for millions of years disintegrated into mini-comets and dust during a smaller part of their dynamical lifetimes. The probability of a collision of an asteroidal or cometary particle during its lifetime with the Earth was maximum at diameter $d\sim 100\,\mu$m. At $d<10\,\mu$m such probability for trans-Neptunian particles was less than that for asteroidal particles by less than an order of magnitude, so the fraction of trans-Neptunian particles with such diameter near Earth can be considerable.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The longitudinal distribution of sunspot activity for 1917-1995 is studied using vector sums of sunspot areas. It is shown that the sunspot distributions behave differently during the Ascending phase and Maximum (AM) of the solar cycle on one hand and for the Declining phase and Minimum (DM) on the other depicting maxima around roughly opposite longitudes. While the maximum of the distribution for the AM period is found around the Carrington longitude of 180$^\circ$, the maximum for the DM period is at the longitude of about 0$^\circ$.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In the pre-WMAP, pre-Supernova-Ia-Hubble-diagram era, quasar lensing statistics stubbornly indicated low values of $\Omega_{\Lambda}$. In contrast, a number of recent lensing statistics studies either find the data support the standard $\Lambda$CDM picture, or simply take the standard cosmological parameters as a given. Have the data or the analyses changed or improved, and how? I review several of the “historical” and the more recent studies, and show that there is no particular measurement, assumption, or model parameter in the old studies that was grossly wrong. Instead, at least several effects, operating together, are likely required in order to achieve agreement between the observations and the currently standard cosmology. Most likely among these effects are: a somewhat lower lensing cross section for elliptical galaxies than assumed in the past; some loss of lensed quasars in optical samples due to extinction by the lenses; and a somewhat lower-than-standard value of $\Omega_{\Lambda}\sim 0.6$. The agreement between recent model calculations and the results of radio lens surveys may be fortuitous, and due to a cancellation between the errors in the input parameters for the lens population and the cosmology, on the one hand, and for the source population, on the other hand.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We use preliminary results of WINGS survey (Fasano et al.) to obtain determinations of optical scaling relations for galaxy clusters. Passing from one- to two- parameter scaling relations we pay particular attention to the Kormendy relation (KR) and to the Fundamental Plane (FP) of galaxy clusters, comparing them with scaling relations of elliptical galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Observations suggest that solar coronal mass ejections (CMEs) are closely associated with reconnection-favored flux emergence, which was explained as the emerging flux trigger mechanism for CMEs by Chen and Shibata (2000) based on numerical simulations. This paper presents a parametric survey of the CME-triggering environment. Our numerical results show that whether the CMEs can be triggered depends on both the amount and the location of the emerging flux. The results are useful for space weather forecast.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The new cutting edge technologies have opened the possibility of using digital spectrometers to probe the sky. With the sampling rate of $\sim$400 Msamples/s and the capability to digitally process data in real-time it is possible to get wideband spectra covering the frequencies in the range 0-200 MHz with the resolution of a few kHz. This presentation will show how such a spectrometer can be applied to the forward-scattering method of meteor detection.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A review of various types of evolved A stars is presented.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Local HII galaxies present a Fundamental Plane of [L–σ] where either the equivalent width of Hβ or the oxygen abundance O/H act as a second parameter. These relations are powerful cosmological distance indicators since emission line galaxies may be found to high redshifts, though some caution must be taken till systematic effects are better understood.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

To correctly take into account the solar wind drag equations for secular variations in the meteoroid orbital semimajor axes and eccentricities were obtained. The equations are similar to those derived for the Poynting- Robertson radiation drag (Wyatt and Whipple 1950). An estimation for the Geminid meteoroid stream shows that the ratios of corpuscular to radiation drags are 0.4 – 0.7 for particles of size $> 10 \mu m$, i.e. the effect is much stronger than was assumed before.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Measuring stellar velocity dispersion (σ) in Narrow-Line Seyfert 1 (NLS1) with optical spectra, can be very difficult because of the large and bright Fe II multiplets, which completely suppress the typically used stellar absorption lines. Indeed, σ values are to date available only for 2 NLS1s. Here we present new σ measurements of three NLS1s observed in the spectral range centered around the Ca II triplet (λ∼8600Å). Moreover, we compare σ with the gaseous velocity dispersion finding that the σ = FWHM([O III]5007Å)/2.35 relation (Nelson & Whittle 1995) is not satisfied by our galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Globular clusters offer ideal laboratories to test the predictions of stellar evolution. When doing so with spectroscopic analyses during the 1990s, however, the parameters we derived for hot horizontal branch stars deviated systematically from theoretical predictions. The parameters of cooler, A-type horizontal branch stars, on the other hand, were consistent with evolutionary theories. In 1999, two groups independently suggested that diffusion effects might cause these deviations, which we verified subsequently. I will discuss these observations and analyses and their consequences for interpreting observations of hot horizontal branch stars.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the long term variation of solar corona based on SOHO/EIT observations from 1996 to 2004. EIT provides diagnostics of bulk corona in three channels with overlapping temperature range from 0.5 MK to 2.7 MK and with high spatial resolution. We find that the coronal emission measure increases by a factor of 4 from $2.0\times10^{27}$ cm$^{-5}$ at the solar minimum to $8.0\times10^{27}$ cm$^{-5}$ at the solar maximum. In the meantime, the overall temperature of the corona increases from 1.3 MK to 1.7 MKTo search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A fast halo CME and correspondingly strong solar burst that occurred in NOAA9684 led to intense geo-effectiveness. The analysis and study in this paper were focused on the evolution of this active region.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Diffraction limited 30m class telescopes will play an important role in gravitational lensing studies, coming online in approximately 2015. As imaging telescopes they will complement the $\sim$6m JWST, probing to smaller angular scales in greatly magnified objects near critical lines and for measuring shear of objects below the JWST angular scale, such as luminous super-star clusters at high redshift. The high source density will allow more detailed mass mapping in the weak lensing regime and will be useful in breaking the cosmology-lens potential degeneracy in strong lensing. As multi-object spectrographs 30m telescopes should provide spectra over the entire optical and near infrared spectrum region. The statistical distribution of redshifts needed to invert projected shear measurements and calibration of photometric redshifts for “tomography” will be available to flux levels around 5-10 nano-Jansky (approx 29.5 m$_{AB}$). However, a one nJy object is expected to require $\sim$500 hours to acquire a redshift, which is most of the dark time in an observing season. Accordingly “gravitational telescopes” will be an important tool for probing the very faint high redshift universe, magnifying a few square arc-seconds at a time by factors of 10-1000.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the preliminary result of our project, consisting in studying the properties of a large sample of galaxy clusters. The Münster Red Sky Survey, which is a large galaxy catalogue covering an area of about 5000 square degrees on the southern hemisphere, serves as our observational basis. It is complete up to $r_F=18^m.3$. Creation of a cluster catalogue is the first step of our investigation. We propose to use the 2D Voronoi tessellation technique for identifying galaxy clusters in this 2D catalogue. Points with high values of the inverse Voronoi tessel area will be regarded as galaxy cluster centroids. We show that this approach works correctly.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We review the discovery of blue metal-poor (BMP) stars and the resolution of this population into blue stragglers and intermediate-age Main-Sequence stars by use of binary fractions. We show that the specific frequencies of blue stragglers in the halo field and in globular clusters differ by an order of magnitude. We attribute this difference to the different modes of production of these two populations. We report carbon and $s$-process enrichment among very metal-poor field blue stragglers and discuss how this result can be used to further resolve field blue stragglers into groups formed during RGB and AGB evolution of their erstwhile primary companions.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The subject of gravitational lensing is now a mature discipline, with an automatic place in cosmology. The robust mass measures provided by lensing are one of the key reasons for having confidence in the standard model of structure formation. For the future, things are more challenging: the next set of interesting questions requires the measurement of small effects with non-trivial systematics. The real question will be whether lensing can overcome these problems rapidly enough that it becomes the most precise probe of the cosmological parameters, in particular the equation of state of the vacuum and its evolution.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We analysed 246 scanned ACO clusters and we do not find any dependence of galaxy cluster ellipticity on redshift.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We report the status of our study of the central region of M 83. Recently a binary mass concentration at the nucleus was suggested by Thatte et al. (2000), and we determined the possible position of the optically hidden mass concentration with 2D Hα kinematics. We continue our study of this region trough IR 3D spectroscopy performed with CIRPASS, attached to the Gemini South telescope. Almost 1500 spectra were obtained, centered in the wavelength 1.3 μm. The velocity field in a region of 13″ × 9″ around the optical nucleus is resolved, with 0.36″ (6.4 pc) sampling. We confirm that the optical nucleus of M 83 is not located at the most important center of symmetry of the velocity field. The largest black hole that could fit to the circular motion in this kinematic center should have a mass less than $2\times10^7M_{\odot}$.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html