A wallpaper map is a conformal projection of a spherical earth onto regular polygons with which the plane can be tiled continuously. A complete set of distinct wallpaper maps that satisfy certain natural symmetry conditions is derived and illustrated. Though all of the projections have been published before, the family had not been characterized as a whole. Some wallpaper maps generalize to one...

We discuss the nature of the photoevaporating circumstellar disks in the Orion Nebula. The structure of thermally driven neutral and ionized ow from the disks is derived through a simple, spherical model. Evaporation ows are self-regulating, and from the estimated mass loss rates we show that it is possible to estimate the present disk masses. Two-dimensional eeects are discussed qualitatively ...

1 The support of the EPSRC under grant no. GR/H 78955, and helpful comments from Tony Cohn, are gratefully acknowledged. Abstract This research report concerns the topology of 2-dimensional regions embedded in spherical surfaces, such as that of the Earth (`spherical regions'). It shows that the RCC (Region-Connection Calculus) rst-order logic formalism for qualitative spatial representation an...

We obtain an exact simple solution of the Einstein equation describing a spherically symmetric cosmological model without the bigbang or any other kind of singularity. The matter content of the model is shear free isotropic fluid with radial heat flux and it satisfies the weak and strong energy conditions. It is pressure gradient combined with heat flux that prevents occurrence of singularity. ...

We discuss the influence of the cosmological background density field on the spherical infall model. The spherical infall model has been used in the Press-Schechter formalism to evaluate the number abundance of clusters of galaxies, as well as to determine the density parameter of the universe from the infalling flow. Therefore, the understanding of collapse dynamics play a key role for extract...

We study the properties of the spin dependent one body density in momentum space for odd–A polarized deformed nuclei within the mean field approximation. We derive analytic expressions connecting intrinsic and laboratory momentum distributions. The latter are related to observable transition densities in p–space that can be probed in one nucleon knock–out reactions from polarized targets. It is...

In contrast to the canonical case, microcanonical thermodynamic functions can show nonanalyticities also for finite systems. In this paper we contribute to the understanding of these nonanalyticities by working out the relation between nonanalyticities of the microcanonical entropy and its configurational counterpart. If the configurational microcanonical entropy ω N (v) has a nonanalyticity at...

Popular models for describing the luminosity-density profiles of dynamically hot stellar systems (e.g., Jaffe, Hernquist, Dehnen) were constructed to match the deprojected form of de Vaucouleurs’ R light-profile. However, we now know that elliptical galaxies and bulges display a mass-dependent range of structural profiles. To compensate this, the model in Terzić & Graham was designed to closely...