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Spectral properties of the binary millisecond pulsar J0437-4715 discovered from a roughly 2 times 10 to the 9th power-year-old neutron star indicate a thermal origin. Particles from the magnetosphere of the pulsar move in the region of the polar cap. Internal friction may heat the surface of the neutron star. Absent surface heating results in the absence of thermal emission, in neutron stars older than 10 to the 5th power years. X-ray pulses of a broad nature are revealed by old pulsars, whereas in the case of young pulsars (not greater than 10 to the 4th power years), sharp bursts of x-ray emission are observed.

During the last 30 years x-ray astronomy has become one of the cornerstones of observational astrophysics. At x-ray wavelengths, we see the 'hot universe'--objects at temperatures of millions to billions [...]

The x-ray source GX5-1 in he galactic bulge has been observed with the position-sensitive proportional counter onboard the Rontgen satellite (ROSAT) during and after a lunar occultation. Extended emission around the source was unambiguously discovered while the central source was behind the lunar rim. This emission is interpreted as a dust-scattering halo around GX 5-1 that has a fractional intensity of 28 percent, implying a grain column density between GX 5-1 and Earth of 3 X [10.sup.10] per square centimeter. The halo derived from imaging during the ROSAT all-sky survey is identical to that obtained from the lunar occultation, thus demonstrating that the ROSAT x-ray mirror scattering has not changed as compared with the mirror properties as measured in preflight calibrations., In the 1960s, the possible existence of halos, produces by the scattering of x-rays off dust grains in the interstellar medium, around the stronger and moderately absorbed x-ray sources was [...]

As of today, seven X-ray sources have been tentatively identified as radio-quiet, isolated neutron stars. The family appears to be a rapidly growing one, although not all the objects have been identified with the same degree of certainty. The most convincing example of radio quiet pulsar is certainly Geminga, the neutron star nature of which, proposed in 1983 on the basis of its similarity with the Vela pulsar, has been firmly established with the discovery of its X and γ pulsation Four more neutron star candidates, originally found in the Einstein data, have been confirmed by ROSAT, which has added to the list two more entries. All this is not the result of an unbiased search. The seven sources were not selected at random: four are inside supernova remnants, an obvious place to search for isolated neutron stars, while the remaining three were singled out because of some peculiarity. Intense γ-ray emission in the case of Geminga, very high X-ray counting rate for RXJ185635-3754, or being the brightest unidentified source in the Einstein medium sensitivity survey, MS 0317-6647. In spite of the limited number of objects and of the observational biases, these seven radio quiet neutron star candidates add valuable pieces of information to the observational panorama of known pulsars. Their properties, inferred from the X-ray emission, offer a coherent picture, pointing towards thermally emitting, cooling neutron stars. [ABSTRACT FROM AUTHOR]

Focuses on the astronomical research contributions by the x-ray satellite ROSAT, Roentgen Satellite named after Wilhelm Conrad Roentgen. Features of the satellite; Containment of a German x-ray telescope and a British ultraviolet telescope; Observations such as discovery of the structural features of the Crab Nebula; Collecting power and low intrinsic background.