Visual, scaled comparisons are made among prominent volcanic, tectonic, crater and impact basin features photographed on various planets and moons in the solar system. The volcanic formation Olympus Mons, on Mars, is 27 km tall, while Io volcanic plumes reach 200-300 km altitude. Valles Marineris, a tectonic fault on Mars, is several thousand

NGC 2841 has been mapped in the J and K near-infrared bands out to some 10 kpc from its center. Maps and radial profiles in micron(J), micron(K) and J-K are presented, and profiles in B-J and B-K derived. The bulge and disk are very well distinguished, but there is also an indication of a bluer ring in the disk between 2 and 7 kpc galactrocentric

A ≡7 hour observation of the central part of the Coma cluster of galaxies has been performed with the EXOSAT LE telescopes and CMA detectors. Five serendipitous sources are detected within the inner 35 arcmin radius of the field. Optical spectroscopy demonstrates that at least three of these are background AGN not associated with the cluster. At

High resolution spectra containing the Mg II h and k resonance doublet have been obtained using the long wavelength spectrometer of IUE, for 7 late-type stars (F0 to G8). In one of these stars, β Hyi, two sharp absorption features were detected against the chromospheric emission cores. Using the study of Crutcher (1982) the authors can employ the

On the basis of the current knowledge about the size of the neutron, the nucleon-nucleon interaction, and the limit on the ratio Gm/c2R 4/9 imposed by General Relativity, the authors find an upper limit of about 2 M_sun;, for stars of uniform density in the neutron phase. The importance of an accurate determination of the neutron radius for

Dynamical problems associated with the orbital motion of dust particles in strong gravitational and radiation fields are analyzed. The general relativistic equations for the motion of a single dust particle are derived, and the static, spherically symmetric situation described by the Schwarzschild metric is considered. Two sharply differentiated