AXAF, the Advanced X-ray Astrophysics Facility will be the third satellite in the series of great observatories in the NASA program, after the Hubble Space Telescope and the Gamma Ray Observatory. At launch in fall 1998, AXAF will carry a high resolution mirror, two imaging detectors, and two sets of transmission gratings (Holt 1993). Important

Results from a numerical and analytical investigation of the solution of a nonlinear axisymmetric diffusion equation for the magnetic field are presented for the case when the nonlinear dependence of the diffusivity nu (B) on the magnetic field satisfies basic physical requirements. We find that for sufficiently strong nonlinearity (i.e., for

The star formation history (SFH) and the properties of the dwarf galaxy LGS 3 are analyzed using color-magnitude (CM) diagrams plotted from VRI photometry of 736 stars. The distance to the galaxy is estimated through the position of the tip or the red giant branch. Two acceptable results have been obtained: 0.77+/- 0.07 Mpc and 0.96+/- 0.07 Mpc

The star formation history (SFH) of the Pegasus dIr, a likely Local Group member at 0.95 Mpc from the Milky Way, is investigated. We characterize the SFH by two basic functions: the star formation rate, psi (t), and the chemical enrichment law, Z(t). It has been derived by comparing the color-magnitude diagram of the resolved stars in Pegasus, with

We derive the relative distances to the Virgo, Fornax and Coma clusters of galaxies by applying the D_n-sigma and the Fundamental Plane (FP) relations to the data of the homogeneous samples of early-type galaxies studied by Caon et al., Lucey et al. and Jorgensen et al. The two distance indicators give consistent results, the relative distance

The number of minor bodies in the Solar System is continuing to increase. More than 30,000 asteroids have been discovered by 1996, and about 7,000 have been catalogued. About 855 comets had known orbits by 1994. The number of known planetary satellites reached 60 (1996). All these minor bodies require improved astrometry, also more accurate