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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,189 records · Page 66
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NASA NTRS1974

Electrographic observations of extended objects. II - The peculiar galaxies NGC 523 and NGC 1614

Electrographic analysis of two highly irregular galaxies, NGC 523 and NGC 1614 using a two dimensional detector with linear response and large information storage, dynamic range, and number of resolution elements is presented. The observation procedure is described, and analysis of the two systems is carried out. Data are graphically represented. The validity of electrographic observation of irregular extragalactic objects is underscored.

Chincarini, G.↗
NASA NTRS1975

The peculiar object HD 44179 /'The red rectangle'/

A strong infrared source detected in the AFCRL sky survey is confirmed, and is identified with the binary star HD 44179, embedded in a peculiar nebula. UBVRI and broad-band photometry between 2.2 and 27 microns are combined with blue, red, and near-infrared spectra, polarimetry and spectrophotometry of the star, and a range of direct and image-tube photographs of the nebula, to suggest a composite model of the system. In this model, the infrared radiation derives from thermal emission by dust grains contained in a disklike geometry about the central object, which appears to be of spectral type B9-A0 III and which may be in pre-main-sequence evolution. Two infrared emission features are found, peaking at 8.7 and 11.3 microns, the latter corresponding to the feature seen in the spectrum of the planetary nebula NGC 7027. The complex nebular structure is discussed on the basis of photographs through narrow-band continuum and emission-line filters. The polarization data support the suggestion of a disk containing some large particles. No radio continuum emission is detected.

Cohen, M.↗
NASA NTRS1974

Recent observations of quasi-stellar objects

Some observational results are discussed which have a bearing on the problem of QSO redshifts. A general description of QSO absorption-line spectra is presented, and the spectra of four objects are reviewed. The hypothesis is advanced that production of absorption lines at many different redshifts is due to line-locking. Two QSOs with redshifts greater than 3 are described, and questions raised by the discovery of a double QSO with two different redshifts are discussed. Efforts to determine associations between QSOs and galaxies are outlined, and some questions are posed concerning physical models, effects of strong gravitational fields, and different types of QSOs.

Burbidge, E. M.↗
NASA NTRS1976

Numerical study of some solar-wind interaction models with space objects

The considerable variety of atmospheric and magnetic field properties possessed by the planets results in a corresponding variety of flow details, and a remarkably rich field of comparative study of solar wind flow around major objects in the solar system. It is the purpose of this paper to present a review of the fluid aspects of these flows and how they are approximated to obtain tractable mathematical problems, and a commentary on possibilities for further improvements and on some misconceptions that have appeared in applications of the results.

Belotserkovskii, O. M.↗
NASA NTRS1976

Comparison of a linear and a nonlinear washout for motion simulators utilizing objective and subjective data from CTOL transport landing approaches

Objective and subjective data gathered in the processes of comparing a linear and a nonlinear washout for motion simulators reveal that there is no difference in the pilot performance measurements used during instrument landing system (ILS) approaches with a Boeing 737 conventional takeoff and landing (CTOL) airplane between fixed base, linear washout, and nonlinear washout operations. However, the subjective opinions of the pilots reveal an important advance in motion cue presentation. The advance is not in the increased cue available over a linear filter for the same amount of motion base travel but rather in the elimination of false rotational rate cues presented by linear filters.

Parrish, R. V.↗
NASA NTRS1975

Minor planets and related objects. XVIII - UBV photometry and surface composition

New photometric observations on the UBV system are presented for 45 asteroids, bringing the total to 91 for which complete UBV colors are available. The reduced magnitudes B (1, 0) scatter about the adopted catalog values by + or - 0m, 25, with negligible systematic difference. The UBV colors fall into three distinct groups which correspond almost perfectly to the S (silicaceous or stony), C (carbonaceous), and U (unclassifiable) asteroid types recently identified from polarimetry, infrared radiometry, and narrow-band spectrophotometry. It becomes possible to classify asteroids from UBV observations alone. The S asteroids have colors very similar to those of L and LL ordinary chondrites, and some of the U objects are consistent in color with nickel-iron or enstatite-rich meteorites, but no meteorites appear to have the UBV colors of the C asteroids. The asteroid C and S compositional types have no exact counterparts among the surfaces of natural satellites.

Zellner, B.↗
NASA NTRS1976

The distribution of redshifts of quasars and related objects

A statistical analysis of some 386 redshifts is conducted together with a numerical simulation of 100 redshifts to evaluate the possibility that a short-wavelength periodic modulation may be present in the redshift distribution of quasars and related compact objects. A previous analysis by Burbidge and O'Dell (1972) is reviewed, and the inclusion of absorption redshifts in the data set is discussed. The results of the present analysis are found not to support claims for the presence of periodic modulations in redshift distribution.

Knight, J. W.↗
NASA NTRS1976

On apparent associations among astronomical objects

An apparent association among bright stars and bright galaxies has been found that has a maximum a posteriori probability for chance occurrence of about 0.008. The ability to find such an association is evidence that apparent associations among objects of different redshifts should be viewed with great caution.

Joss, P. C.↗
NASA NTRS1976

An iterative algorithm for objective wind field analysis

Three different algorithms for objective wind field analysis were tested on the same set of initial conditions: Dickerson-Sasaki's 'strong constraint' algorithm, a fixed-vorticity algorithm, and a newly proposed fixed-station-velocity algorithm. The three methods are compared with respect to the degree of minimization of wind divergence and the accuracy of wind data at a measured station. The first two techniques, though they reduce wind divergence, produce wind vectors substantially different from the observed values. The proposed iterative scheme is similar to Endlich's (1967) procedure for treating a macroscale wind field, and minimizes divergence while retaining the observed wind vectors.

Liu, C. Y.↗
NASA NTRS1976

The IMS satellite programme - Scientific objectives

The International Magnetospheric Study (IMS) will make use of a number of satellites launched by the ESA, Japan, the USA, and the USSR. The instrumentation carried by these satellites is considered, taking into account GEOS, ISEE-A, ISEE-B, ISEE-C, EXOS-A, EXOS-B, and ISS. The morphology of the magnetosphere is examined and questions regarding the origin of substorms are investigated. IMS objectives are discussed, giving attention to the macroscopic behavior of the magnetosphere, microscopic processes, approaches to be used for monitoring the state of the magnetosphere, and magnetosphere-ionosphere coupling.

Russell, C. T.↗
NASA NTRS1976

Cloud acceleration by cosmic rays in the vicinity of compact luminous objects

Nonrelativistic cosmic rays from a central source exert an outward pressure on the surrounding gas in a Seyfert nucleus or the envelope of a quasi-stellar object. This force is different from radiation pressure in that the momentum transfer to the gas is enhanced rather than reduced when the gas is ionized. Calculations are presented to show that particle energy flux comparable to observed photon luminosities will accelerate gas clouds as large as 100,000 solar masses to velocities on the order of 0.1c in the presence of a central mass of 100 million solar masses.

Eilek, J. A.↗
NASA NTRS1976

Dynamical study of the Hilda asteroids. I - Resonant orbital motion of the PLS objects from the Palomar-Leiden Survey

Schubart's (1968) model of a planar elliptic restricted three-body problem is used to study the orbital motion of the Hilda asteroids from the Palomar-Leiden Survey. The 3:2 resonant coupling to Jupiter of some of these small asteroids is found to be stable. However, some of the small asteroids with absolute magnitude greater than 15 have large amplitude of variation in their orbital elements in one libration period. Since the lifetime scales against catastrophic collision of the Hilda asteroids are estimated to be several times larger than those of the main-belt objects, a significant portion of these resonant asteroids could be the original members of the Hilda group. From this point of view, it is suggested that such 'size dependence' of resonant orbital motions might be the result of cosmogonic effects of jet-stream accretion.

Ip, W.-H.↗
NASA NTRS1977

On possible associations of quasi-stellar objects and radio galaxies with rich clusters of galaxies

A comparison of the cataloged coordinates of QSOs and of 3CR galaxies with those of Abell's rich clusters of galaxies yields the following results: (1) There is no statistically significant evidence that high-redshift QSOs lie preferentially close to Abell clusters. (2) There is no statistically significant evidence that low-redshift QSOs lie preferentially close to Abell clusters. (3) There is (as is well known) highly significant evidence that 3CR galaxies lie preferentially close to Abell clusters. (4) The distributions of angular separations between QSOs and clusters and between 3CR galaxies and clusters differ at statistically significant (but not highly significant) levels. In view of these results, a generic relationship between low-redshift QSOs and radio galaxies seems questionable. This result for the QSOs is also entirely consistent with the idea that they are 'local' objects with redshifts of noncosmological origin.

Roberts, D. H.↗
NASA NTRS1977

Ultraviolet spectrum of quasi-stellar object 3C273

The first direct observation of the ultraviolet spectrum of a quasi-stellar object (QSO) has been made with a rocket-borne telescope. The emission line spectrum of 3C273 is similar to the spectra of high-redshift QSOs, but no absorption is observed. The results provide important new constraints on theoretical models of QSOs, place a severe limit on the density of neutral hydrogen in the intergalactic medium, and suggest a cosmological origin for much of the absorption seen in high-redshift QSOs. Comparison of the ultraviolet spectrophotometry of low- and high-redshift QSOs suggests that the universe is closed, with a deceleration parameter of about 1.

Davidsen, A. F.↗
NASA NTRS1977

Research and Technology Objectives and Plans Summary (RTOPS)

The NASA Research and Technology program for FY 1978 is represented by this compilation of the 'Summary' portions of each of the Research and Technology Objectives and Plans (RTOPS). The RTOP Summary is designed to facilitate communication and coordination among concerned technical personnel in government, in industry, and in universities. The first section contains citations and abstracts of the RTOPs. Following this section are four indexes: Subject, Technical Monitor, Responsible NASA Organization, and RTOP Number.

Source record↗
NASA NTRS1978

Planned flight test of a mercury ion auxiliary propulsion system. 1: Objectives, systems descriptions, and mission operations

A planned flight test of an 8 cm diameter, electron-bombardment mercury ion thruster system is described. The primary objective of the test is to flight qualify the 5 mN (1 mlb.) thruster system for auxiliary propulsion applications. A seven year north-south stationkeeping mission was selected as the basis for the flight test operating profile. The flight test, which will employ two thruster systems, will also generate thruster system space performance data, measure thruster-spacecraft interactions, and demonstrate thruster operation in a number of operating modes. The flight test is designated as SAMSO-601 and will be flown aboard the shuttle-launched Air Force space test program P80-1 satellite in 1981. The spacecraft will be 3- axis stabilized in its final 740 km circular orbit, which will have an inclination of approximately greater than 73 degrees. The spacecraft design lifetime is three years.

Power, J. C.↗
NASA NTRS1978

Nuclear gamma rays from compact objects

Accreting compact objects may be important gamma ray line sources and may explain recent observations of celestial gamma-ray line emission from a transient source in the direction of the galactic anti-center, from the galactic center, and possibly from the radio galaxy Centaurus A. The identification of the lines from the transient source requires a strong redshift. Such a redshift permits the identification of these lines with the most intense nuclear emission lines expected in nature, positron annihilation, and neutron capture on hydrogen and iron. Their production as a result of nuclear interactions in accreting gas around a neutron star is proposed. The gamma-ray line emission from the galactic center and possibly Centaurus A appears to have a surprisingly high luminosity, amounting to perhaps as much as 10% of the total luminosity of these sources. Such high gamma-ray line emission efficiencies could result from nuclear interactions in accreting gas around a massive black hole.

Lingenfelter, R. E.↗
NASA NTRS1978

X-ray observations of BL Lac objects

The BL Lac objects MK501 and MK421 were observed with OSO-8 and HEAO-1 X-ray detectors in the 2-60 keV band. Their spectra are similar with best fitting power laws having energy index -.4 alpha 4. A soft X-ray excess is indicated in their spectra. There was no detectable X-ray absorption with implied column densities N sub H 1.5 x 10 to the 22d power at sq cm. MK421 was a factor 6 weaker in November 1977 than in May 1977. An identification of PKS0548-322 with a new source H0548,-32 is suggested.

Mushotzky, R. F.↗