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At least 1,099 records · Page 61
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

A discussion of the H-alpha filamentary nebulae and galactic structure in the Cygnus region

From observation of the galactic structure in Cygnus, the system of filamentary nebulae was found to lie at a distance of roughly 1.5 kpc, in the same region as about half the thermal radio sources in Cygnus X, the supernova remnant near gamma Cygni, and the association Cygnus OB2, in the direction of which the X-ray source Cygnus XR-3 is observed. The source of excitation was probably the pulse of radiation from a supernova explosion, as proposed in the case of Gum nebula. However continuing excitation by early stars in the region of Cygnus X cannot be excluded.

Matthews, T. A.↗
NASA NTRS1972

Noncontacting device to indicate deflection of turbopump internal rotating parts

Phase 2 (development) which was concluded for the ultrasonic Doppler device and the light-pipe-reflectance device is reported. An ultrasonic Doppler breadboard system was assembled which accurately measured runout in the J-2 LOX pump impeller during operation. The transducer was mounted on the outside of the pump volute using a C-clamp. Vibration was measured by conducting the ultrasonic wave through the volute housing and through the fluid in the volute to the impeller surface. The impeller vibration was also measured accurately using the light-pipe probe mounted in an elastomeric-gland fitting in the pump case. A special epoxy resin developed for cryogenic applications was forced into the end of the fiber-optic probe to retain the fibers. Subsequently, the probe suffered no damage after simultaneous exposure to 2150 psi and 77 F. Preliminary flash X-radiographs were taken of the turbine wheel and the shaft-bearing-seal assembly, using a 2-megavolt X-ray unit. Reasonable resolution and contrast was obtained. A fast-neutron detector was fabricated and sensitivity was measured. The results demonstrated that the technique is feasible for integrated-time measurements requiring, perhaps, 240 revolutions to obtain sufficient exposure at 35,000 rpm. The experimental verification plans are included.

Hamilton, D. B.↗
NASA NTRS1971

Glancing incidence optics for X-ray and ultraviolet astronomy.

Glancing incidence telescopes of the kind first described by Wolter have now been physically realized, so that it is possible to obtain high-resolution images of celestial objects at all wavelengths greater than about 3 A. The GSFC-MSFC X-ray telescope for the Apollo telescope mount uses Wolter type 1 optics and is capable of forming images of the sun in the 8-70 A region with spatial resolution of the order of one arc second. The GSFC extreme ultraviolet spectroheliometer for OSO H uses type 2 optics and can obtain images of the sun in spectral lines in the 170-400 A region with a spatial resolution of about ten arc seconds. Theoretical (ray trace) and laboratory data on these systems are presented.

Underwood, J. H.↗
NASA NTRS1972

Soft X-rays from Cygnus X-2 and from Cygnus X-1 /in eclipse/.

Observations of Cygnus X-1 (probably in eclipse) and Cygnus X-2 on Oct. 23, 1971, show quite low absorption in their spectrum, and yet they are thought to be in a double or multiple star system from the optical data. The lack of intrinsic absorption in their spectra may be taken to mean that they lie sufficiently far from their primaries for a reduction to virtually zero of their interaction with the atmosphere of the primaries.

Stevens, J. C.↗
NASA NTRS1973

High energy and solar astronomy, overview

A survey of our own galaxy and neighboring galaxies using X-rays, gamma rays, and cosmic rays is outlined. High energy astrophysic results suggest the presence of a new acceleration mechanism where the inflow of matter on collapsed objects seems to be one of the sources of complex time variations in binary systems.

Mcdonald, F. B.↗
NASA NTRS1974

Physical parameters of the Cen X-3 system

Photographic spectra of Cen X-3 show that the primary star has a spectral type near 06.5 with weak, variable emission at wavelength 4640 and 4686. No orbital motion of the emission or absorption lines is detected; for the latter the upper limit is approximately + or - 50 km/s. Analysis of the available data indicates that the primary is a factor of 2-3 less massive than expected from normal evolutionary models while the X-ray source has a solar mass near 1.5.

Osmer, P. S.↗
NASA NTRS1975

Significant Accomplishments in Science and Technology

The proceedings of a symposium on significant accomplishments in science and technology are presented. The symposium was held at the Goddard Space Flight Center in December 1973. The subjects discussed are as follows: (1) cometary physics, (2) X-ray and gamma ray astronomy, (3) solar and terrestrial physics, (4) spacecraft technology, (5) Earth Resources Technology Satellite, (6) earth and ocean physics, (6) communications and navigation, (7) mission operations and data systems, and (8) networks systems and operations.

Source record↗
NASA NTRS1975

Physical parameters of the Centaurus X-3 system

Photographic spectra of Cen X-3 show that the primary star has a spectral type near O6.5 with weak, variable emission at 4640 and 4686 A. No orbital motion of the emission or absorption lines is detected; for the latter the upper limit is about plus or minus 50 km/sec. Analysis of the available data indicates that the primary is a factor of 2-3 less massive than expected from normal evolutionary models while the X-ray source has a mass near 1.5 times the solar mass.

Osmer, P. S.↗
NASA NTRS1976

The Identification of Scientific Programs to Utilize the Space Environment

A program to identify and develop ideas for scientific experimentation on the long duration exposure facility (LDEF) was completed. Four research proposals were developed: (1) Ultra pure germanium gamma ray radiation detectors in the space environment, intended to develop and demonstrate an X-ray and gamma-ray spectroscopy system incorporating a temperature cyclable high-purity germanium detector and diode heat pipe cryogenic system for cooling, (2) growth, morphogenesis and metabolism of plant embryos in the zero-gravity environment, to investigate if the space environment induces mutations in the embryogenic cells so that mutants of commercial significance with desirable attributes may be obtained, (3) effect of zero gravity on the growth and pathogenicity of selected zoopathic fungi. It is possible that new kinds of treatment for candidiasis, and tichophytosis could eventuate from the results of the proposed studies, and (4) importance of gravity to survival strategies of small animals. Gravitational effects may be direct or mediate the selection of genetic variants that are preadapted to weightlessness.

Kulacki, F. A.↗
NASA NTRS1976

The positions and proper motions of HZ Herculis and 12 neighboring stars

The positions and proper motions of HZ Her, the optical counterpart of the X-ray source Her X-1, and 12 field stars are determined in the system of the FK4. The proper motion of HZ Her is consistent with that expected for an object with a relatively low peculiar velocity located at the approximate 3-kpc distance estimated for Her X-1.

Gatewood, G.↗
NASA NTRS1976

Evidence for a 17-d periodicity from Cyg X-3

Data are presented from the Ariel-V All-Sky Monitor which indicate a 17-day periodicity of the X-ray spectra from Cyg X-3 (3U2030+40). The data are consistent with data from the Ariel V Sky Survey Experiment. Assuming that the high intensity state of Cyg X-3 is well fitted by a structureless black body (Serlemitsos et al., 1975), and that the 17-day maxima correspond to increased electron scattering in the source, it is suggested that the 17-day effect is analogous to the 35-day variation in Her X-1. The possible explanation of this phenomenon as a result of the 17-day orbital period of the binary system containing Cyg X-3 is severely constrained by the stability of the well-known 4.8-hour variation.

Holt, S. S.↗
NASA NTRS1978

Calibration faceplate for x-ray image intensifiers

Lead crosshairs embedded in detachable, radiolucent intensifier faceplate offers quantitative measurement for X-ray image intensifier. Faceplate provides x-y reference system external to device being photographed.

Rasmussen, D.↗
NASA NTRS1976

Vignetting characteristics of the S-056 X-ray telescope

A ray trace analysis of the vignetting characteristics of the S-056 X ray telescope is presented. The relative energy is calculated in the spot formed in the focal plane of the S-056 X ray telescope by an off axis point source at infinity for off axis angles of 0, 1, 2, ..., 35 arc minutes. At each off axis angle, the relative energies are evaluated using theoretical X ray reflectivity curves for wavelengths of 8.34 A, 17.57 A, and 27.39 A, and also using an experimental X ray reflectivity curve for 8.34 A. The effects of vignetting due purely to the geometry of the S-056 optical system are evaluated separately, as well as jointly with the effects of mirror reflectivity.

Foreman, J. W., Jr.↗
NASA NTRS1976

Orbital precession in Hercules X-1

It is noted that the 35-day X-ray high-low cycle of Her X-1 could be explained in terms of periodic obscuration of the source by a tilted and precessing 'slaved' accretion disk, which would require precession of the mass-shedding star and, consequently, a precessing binary orbit. Four months of Uhuru data obtained in 1972 are analyzed to determine whether the orbital precession can be detected as a Doppler modulation in the arrival times of the 1.24-sec X-ray pulsations. The precession geometry is examined, the test for precession is outlined, and a marginally significant indication of orbital precession in the Hz Her/Her X-1 system is obtained. Possible biases in the analysis are evaluated, and the spin-axis misalignment of HZ Her is estimated from the measured tilt of the orbit.

Deeter, J. E.↗
NASA NTRS1977

X-ray sources in stellar winds

A model of a binary X-ray source immersed in a stellar wind from its companion star is considered. The geometry of the constant ionization and temperature contours in the model is discussed, and X-ray radiative transfer through the wind is described. The results are applied to make predictions about the presence and variability of iron K-shell fluorescence lines, to explain the light curve of Cen X-3 during a 'low' to 'high' state transition in July 1972, and to predict variability with orbital phase of resonance ultraviolet lines such as N V at 1238 and 1242 A from the binary system.

Hatchett, S.↗
NASA NTRS1977

A candidate mission using the Shuttle and solar electric propulsion

It is suggested that an out-of-the-ecliptic solar electric propulsion (SEP) mission be performed. Data would be gathered pertaining to the three-dimensional structure of solar features at radio and X-ray wavelengths, the properties of the solar wind as a function of latitude and time, the configuration of the interplanetary field and its relation to solar fields, and the modulations of cosmic rays to determine the spectrum of interstellar cosmic rays. The mission would also, it is thought, demonstrate the capability of SEP for use in Shuttle missions. The SEP spacecraft and the ongoing development of related systems are examined. The weight of a SEP stage is contrasted with the weight of a chemical rocket stage.

Duxbury, J. H.↗
NASA NTRS1977

Neutral particle background in cosmic ray telescopes composed of silicon solid state detectors

The energy loss-spectrum of secondary charged particles produced by the interaction of gamma-rays and energetic neutrons in silicon solid state detectors has been measured with a satellite-borne cosmic ray telescope. In the satellite measurements presented here two distinct neutral background effects are identified: secondary protons and alpha particles with energies of about 2 to 100 MeV produced by neutron interactions, and secondary electrons with energies of about 0.2 to 10 MeV produced by X-ray interactions. The implications of this neutral background for satellite measurements of low energy cosmic rays are discussed, and suggestions are given for applying these results to other detector systems in order to estimate background contamination and optimize detector system design.

Mewaldt, R. A.↗
NASA NTRS1978

Soft X-ray results from the Wisconsin experiment on OSO-8

Design features and capabilities of a soft X-ray instrument aboard OSO 8 are discussed, and results are presented for observations of AM Her, Her X-1, and Eta Car. The observations of AM Her indicate that: (1) the spectrum is composite, with a very steep or very-low-temperature component plus a rather flat or very-high-temperature component; (2) the relative phase of soft X-ray minimum and optical V-band primary minimum has remained stable over the interval between 1975 'high-state' observations and 1976 'low-state' observations; and (3) the times of soft X-ray minima and hard X-ray maxima coincide, to within the accuracy of the observations. For Her X-1, soft X-ray turn-on is found to lag behind hard X-ray turn-on by no more than 3 hr. It is suggested that little or no absorption of the soft X-ray component occurs during the on state by cool gas within the Her X-1 system. A strong source with a spectrum peaked between 0.4 and 1.5 keV has been detected which is consistent with a point source at the position of Eta Car.

Bunner, A. N.↗