Astrophysics
The existence or otherwise of X-ray luminous star-forming galaxies has been an open question since the era of the Einstein satellite. Various authors have claimed the discovery of X-ray luminous star-forming galaxies but in many cases more…
We present the first mid-infrared (Mid-IR) ($\lambda5-15\mu$m) and radio continuum ($\lambda\lambda$20,~6 and 3.6 cm) observations of the star-forming collisional ring galaxy VII Zw 466 and its host group made with the Infrared Space…
I show that the self-consistent solution of the problem of MHD plasma flow in magnetosphere of an oblique rotator with an initially split-monopole magnetic field is reduced to the solution of the similar problem for the axisymmetric…
The star formation history of the dE NGC 185, together with its spatial variations, has been investigated using new ground-based $H_\alpha$ and $BVI$ photometry, and synthetic color--magnitude diagrams (CMDs). We find that the bulk of the…
We report new statistical equilibrium calculations for Fe I and Fe II in the atmosphere of Late-Type stars. We used atomic models for Fe I and Fe II having respectively 256 and 190 levels, as well as 2117 and 3443 radiative transitions.…
Redshifts of several galaxies thought to be associated with NGC 326 are determined. The results confirm the presence of a cluster and find a mean redshift of z = 0.0477 +/- 0.0007 and a line-of-sight velocity dispersion sigma_{z} = 599…
We present results from the cross-correlation of the spectroscopic atlas of Ho etal (1995) with the ROSAT All-Sky Survey Bright Source Catalogue, in an attempt to understand the X-ray emission mechanisms in nearby galaxies. The resulting…
We report spectro-imaging observations of the bright western ridge of the supernova remnant IC 443 obtained with the ISOCAM circular variable filter (CVF) on board the Infrared Space Observatory (ISO). This ridge corresponds to a location…
Measurements of the Cosmic Microwave Background Radiation (CMBR) provide a powerful tool for measuring the primary cosmological parameters. However, there is a large degree of parameter degeneracy in simultaneous measurements of the matter…
We explore some basic observational consequences of assuming that the dark matter in the Milky Way consists mainly of molecular clouds, and that cosmic rays can penetrate these clouds. In a favoured model of the clouds, this penetration…
It is shown that double inflation (two minimally coupled massive scalar fields) can produce correlated adiabatic and isocurvature primordial perturbations. Depending on the two relevant parameters of the model, the contributions to the…
We have obtained deep surface photometry of the edge-on spiral galaxy NGC 4244. Our data reliably reach 27.5 R magnitude arcsec^{-2}, a significant improvement on our earlier deep CCD surface photometry of other galaxies. NGC 4244 is a…
We suggest a new method of estimating distances to X-ray pulsars and their magnetic fields. Using observations of fluxes and period variations in the model of disk accretion one can estimate the magnetic momentum of a neutron star and the…
We investigate when and how a dusty starburst galaxy merger can be heavily obscured by dust and consequently becomes an ultra-luminous infrared galaxy (ULIRG), based on numerical simulations of chemodynamical and photometric evolution of…
We investigate different accretion disk models and viscosity prescriptions in order to provide a basic explanation for the exotic temporal behavior in GRS 1915+105. Based on the fact that the overall cycle times are very much longer than…
We report the detection of three mercury-manganese stars in the Orion OB1 association. HD 37886 and BD-0 984 are in the approximately 1.7 million year old Orion OB1b. HD 37492 is in the approximately 4.6 million year old Orion OB1c. Orion…
Detailed composition measurements can be a very powerful means of tracing origins, a fact used regularly by forensic scientists and art historians. One of the main motivating factors for making detailed observations of cosmic rays was…
The small Antlia-Sextans clustering of galaxies is located at a distance of only 1.36 Mpc from the Sun, and 1.72 Mpc from the adopted barycenter of the Local Group. The latter value is significantly greater than the radius of the zero-…
We have developed a new technique for weak lensing analysis, with which the effect of the point spread function (PSF) on small galaxy images can be corrected for accurately. Rather than relying on weighted second moments of detected images,…
We present RXTE observations of the soft gamma--ray repeater SGR 1900+14 taken September 4-18, 1996, nearly 2 years before the 1998 active period of the source. The pulsar period (P) of 5.1558199 +/- 0.0000029 s and period derivative (Pdot)…