Astrophysics
The problem of the anisotropic Inverse Compton scattering between a monochromatic photon beam and relativistic electrons is revisited and formally solved without approximations. Solutions are given for the single scattering with an electron…
In this paper we semianalyticaly evaluate influence of the exponential decay of magnetic field on the fate of isolated neutron stars. The fact of ROSAT observations of several X-ray sources, which can be accreting old isolated neutron stars…
We investigate inertial mode oscillations of slowly and uniformly rotating, isentropic, Newtonian stars. Inertial mode oscillations are induced by the Coriolis force due to the star's rotation, and their characteristic frequencies are…
The arrival directions of extremely high energy cosmic rays (EHECR) above $4\times10^{19}$ eV, observed by four surface array experiments in the northern hemisphere,are examined for coincidences from similar directions in the sky. The total…
The BL-Lac family of active galaxies possess almost featureless spectra and exhibit rapid variability over their entire spectral range. A number of models have been developed to explain these extreme properties, several of which have…
We present 2D hydrodynamic simulations of circumstellar disks around protostars using a `Piecewise Parabolic Method' (PPM) code. We include a point mass embedded within the disk and follow the migration of that point mass through the disk.…
We give a progress report on a snapshot 86 GHz-VLBI survey of the EGRET blazars with the observatories of the CMVA. A high fraction (17/18) of the EGRET blazars were detected on the Pico Veleta-Onsala baseline with a baseline length on the…
Spectrophotometric observation of the gravitationally microlensed quasar Q2237+0305 during a High Magnification Event (HME) is potentially a very powerful tool for probing the structure of the quasars accretion disc on scales of less than…
Interactions between galaxies have spectacular effects on gas dynamics, and small galaxy groups are a privileged place to investigate them. In particular, they could test the existence of cold H2 gas as dark matter in the outer parts of…
We present J and Ks band galaxy counts down to J=24 and Ks=22.5 obtained with the new infrared imager/spectrometer, SOFI, at the ESO New Technology Telescope. The co-addition of short, dithered, images led to a total exposure time of 256…
We describe the evolution of galaxies in a chemically consistent way accounting for the increasing initial metallicity of successive generations of stars. The enrichment of various types of model galaxies is compared with Damped Ly$\alpha$…
This paper outlines a way to determine the ICF using only infrared data. We identify four line pairs, [NeIII] 36$\micron$/[NeII] 12.8$\micron$, [NeIII]~15.6$\micron$ /[NeII] 12.8$\micron$, [ArIII] 9$\micron$/[ArII] 6.9$\micron$, and [ArIII]…
Nature produces cosmic ray particles, probably protons, with energies well above $10^{20}$ eV -- how are they produced? Where do they come from? Gamma rays with energies above $10^{13}$ eV are produced in jets of active galaxies -- are…
We present a semi-analytic study of the equilibrium models of close binary systems containing a fluid star (mass $m$ and radius $R_0$) and a Kerr black hole (mass $M$) in circular orbit. We consider the limit $M\gg m$ where spacetime is…
In recent years, much studies have focused on determining the origin of the large-scale line-profile and/or photometric patterns of variability displayed by some apparently single Wolf-Rayet stars, with the existence of an unseen…
We analyse a sample of 507 evolved stars in the inner galactic Plane. We derive average ages for subsets of this sample and use those sets as beacons for the evolution of the Galaxy. In the Bulge the oldest OH/IR stars in the plane are 7.5…
An amended formula for the decay of radioactive material is presented. It is a modification of the standard exponential formula. The new formula applies for long cosmic times that are comparable to the Hubble time. It reduces to the…
We observed the HH24-26 region in the L1630 Orion molecular cloud complex with the X-ray observatory ASCA in the 0.5$-$10 keV band. X-ray emission was detected from the T Tauri star SSV61 and from the region where the Class I protostars…
We use a hydrodynamical N-body code to generate simulated maps, of size one square degree, of the thermal SZ effect. We study three different cosmologies; the currently-favoured low-density model with a cosmological constant, a…
(abridged) We present and discuss our observations of the NL quasar PG1404+226 with ASCA and HST, and a re-analysis of our earlier observations with ROSAT. The soft X-ray spectrum is very steep and displays an absorption feature (edge or…