Astrophysics
The distance to NGC 7331 has been derived from Cepheid variables observed with HST/WFPC2, as part of the Extragalactic Distance Scale Key Project. Multi-epoch exposures in F555W (V) and F814W (I), with photometry derived independently from…
We have found that the bulge of the large, nearby Sb galaxy NGC 7331 rotates retrograde to its disk. Analysis of spectra in the region of the near-IR Ca II triplet along the major axis shows that, in the radial range between 5'' and ~20'',…
We present a survey of the photometric and kinematic properties of 39 nearby, nearly face-on disk galaxies. Our approach exploits echelle-resolution integral-field spectroscopy of the H-alpha regions, obtained with DensePak on the WIYN 3.5m…
The neutralino, the lightest stable supersymmetric particle, is a strong theoretical candidate for the missing astronomical ``dark matter''. A profusion of such neutralinos can accumulate near the Sun when they lose energy upon scattering…
The nature of Compact Groups (CGs) is investigated by comparing the luminosities and morphologies of CG galaxies, CG Neighbours and Isolated galaxies. CGs turn out to include more early type galaxies than Isolated galaxies and fewer…
We explore a broad class of three-parameter inflationary models, called the $\Lambda$-inflation, and its observational predictions: high abundance of cosmic gravitational waves consistent with the Harrison-Zel'dovich spectrum of primordial…
Intriguing parallels between density fluctuation power versus wavenumber on small (mm) and large (Mpc) scales are presented. The comparative study is carried out between fusion plasma measurements and cosmological data. Based on predictions…
We present the results of 20 ksec Chandra observations for each of 5 radio galaxies in the redshift range 2.0 < z < 2.6. For 4 of the 5 targets we detect unresolved X-ray components coincident with the radio nuclei. From spectral analysis…
Aims:We aim to significantly increase the number of detected extra-solar planets in a magnitude-limited sample to improve our knowledge of their orbital element distributions and thus obtain better constraints for planet-formation models.…
We revisit the gravitational lensing phenomenon using a new visualization technique. It consists in projecting the observers sky into the source plane, what gives rise to a folded and stretched surface. This provides a clear graphical tool…
Several analyses of the cosmic microwave background map made by the satellite WMAP suggest that the global shape of a spatial section of the Universe is that of a Poincare dodecahedral space. A summary of some of these analyses and a…
The multiwavelength spectrum of BL Lacertae during its July 1997 outburst is analyzed in terms of different variations of the homogeneous leptonic jet model for the production of high-energy radiation from blazars. We find that a…
(Abridged) Using a 100 ks XMM-Newton exposure of NGC 4051, we show that the time evolution of the ionization state of the X-ray absorbers in response to the rapid and highly variable X-ray continuum constrains all the main physical and…
The results from a Hubble Space Telescope (HST) snapshot survey of post-AGB objects are shown. The aim of the survey is to complement existing HST images of PPN and to connect various types of nebulosities with physical and chemical…
Many different mechanisms can contribute to antiprotons and positrons production, ranging from conventional reactions up to exotic processes like neutralino annihilation. The open problems are so fundamental (i.e.: is the universe symmetric…
Stable neutrino and U quark of 4th generation are excluded neither by experimental data, nor by astrophysical constraints. Moreover, excess of stable $\bar U$ quarks in the Universe can lead to an exciting composite nuclear-interacting form…
A hypercritical value for the magnetic field is determined, which provides the full compensation of the positronium rest mass by the binding energy in the maximum symmetry state and disappearance of the energy gap separating the…
Solar neutrino flares astronomy is at the edge of its discover. High energy flare particles (protons, alpha) whose self scattering within the solar corona is source of a rich prompt charged pions are also source of sharp solar neutrino…
A direction sensitive dark matter detector using organic crystals is being developed. It exploits the anisotropic scintillation efficiency of organic crystals with respect to the direction of nuclear recoils relative to crystallographic…
Neutrino oscillations in a core-collapse supernova may be responsible for the observed rapid motions of pulsars. Three-dimensional numerical calculations show that, in the absence of neutrino oscillations, the recoil velocities of neutron…