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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 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

The effect of immobilization and 3 (beta-aminoethyl)-1, 2, 4 triazol on the calcium content in gastric tissues of guinea pigs during the formation of experimental ulcers

A sharp fall in the concentration of calcium in gastric tissues upon immobilization and after administration of the histamine analog was recorded. Similar shifts were seen to occur in the blood plasma as well. This implies that under the effect of different action, tissue dystrophy develops by following a common mechanism involving not only the adenyl cyclase system, but that of calcium ion metabolism as well. The calcium ion content in the blood plasma and gastric tissues were measured by atomic absorption spectrophotometry.

Grechishkin, L. L.↗
NASA NTRS1980

The composition of the Martian dark regions: Observations and analysis

Near infrared telescopic spectrophotometry for dark regions is present and interpreted using laboratory studies of iron bearing mineral mixtures and terrestrial oxidized and unoxidized basalts. Upon closer inspection (by spacecraft) the telescopic dark regions were found to consist of large scale intermixtures of bright soil (aeolian dust) and dark materials. The dark materials themselves consist of an intimate physical association of very fine grained ferric oxide bearing material with relatively high near infrared reflectance and darker, relatively unoxidized rocks or rock fragments. While these two components could exist finely intermixed in a soil, a number of lines of evidence indicate that the usual occurrence is probably a thin coating of physically bound oxidized material. The coated rocks are dark and generally clinopyroxene bearing. The shallow band depths and low overall reflectances indicate that opaque minerals such as magnetite are probably abundant.

Singer, R. B.↗
NASA NTRS1981

Highly-evolved stars

The ways in which the IUE has proved useful in studying highly evolved stars are reviewed. The importance of high dispersion spectra for abundance analyses of the sd0 stars and for studies of the wind from the central star of NGC 6543 and the wind from the 0 type component of Vela X-1 is shown. Low dispersion spectra are used for absolute spectrophotometry of the dwarf nova, Ex Hya. Angular resolution is important for detecting and locating UV sources in globular clusters.

Heap, S. R.↗
NASA NTRS1981

The carbon abundance in two h 2 regions of the small Megallanic Cloud

Observations of the ultraviolet spectra of two locations in the H II region NGC 346 and of the entire H II region IC 1644 in the Small Magellanic Cloud (SMC) were made using the International Ultraviolet Explorer (IUE) satellite. The abundance of carbon in the nebulae was derived using theoretical model analysis combined with ground-based spectrophotometry of other emission lines. The abundance of C relative to H in the SMC was found to be lower by -0.9 dex compared with the Sun and lower by -0.8 dex compared with the Orion Nebula. This C deficiency is similar to that of O, Ne, S, and Ar in the SMC, but not as great as found for N. The sites and history of C nucleosynthesis in galaxies is similar to that of O, Ne, S, and Ar, in contrast to that of N, which appears to be more complex, perhaps because of a mixture of secondary primary sources or a significant contribution from intermediate-mass long-lived stars.

Dufour, R. J.↗
NASA NTRS1975

Report of the facility definition team spacelab UV-Optical Telescope Facility

Scientific requirements for the Spacelab Ultraviolet-Optical Telescope (SUOT) facility are presented. Specific programs involving high angular resolution imagery over wide fields, far ultraviolet spectroscopy, precisely calibrated spectrophotometry and spectropolarimetry over a wide wavelength range, and planetary studies, including high resolution synoptic imagery, are recommended. Specifications for the mounting configuration, instruments for the mounting configuration, instrument mounting system, optical parameters, and the pointing and stabilization system are presented. Concepts for the focal plane instruments are defined. The functional requirements of the direct imaging camera, far ultraviolet spectrograph, and the precisely calibrated spectrophotometer are detailed, and the planetary camera concept is outlined. Operational concepts described in detail are: the makeup and functions of shuttle payload crew, extravehicular activity requirements, telescope control and data management, payload operations control room, orbital constraints, and orbital interfaces (stabilization, maneuvering requirements and attitude control, contamination, utilities, and payload weight considerations).

Source record↗
NASA NTRS1980

An ultraviolet extinction study of the rho Ophiuchi dark cloud

Five-band ultraviolet spectrophotometry has been carried out for 54 stars in the upper Scorpius complex. Of these, 14 stars in the rho Ophiuchi dark cloud and 13 in the surrounding area are found to be free of spectral peculiarities and contamination by scattered light from nearby bright stars. The dark cloud stars give extinction curves which are significantly lower than the average extinction curves derived by other investigators and also those observed for localized regions such as the area around Cygnus X-1 and the Cepheus OB III cluster. This implies that the dust in the upper Scorpius region, especially that in the rho Ophiuchi dark cloud has larger average size than the normal interstellar medium. R, the ratio of total-to-selective extinction, is found to be 4.2. The effects of a lower extinction curve on the chemistry of a dark cloud is also briefly discussed.

Wu, C.-C.↗
NASA NTRS1980

HR 4453 - An anomalously bright UV source

Crawford et al. (1979) reported that HR 4453 has an anomalously large UV flux in the 1350-1600 A band. This paper reports results of the UV spectrophotometry of HR 4453 obtained with the Copernicus satellite. Portions of the spectrum from 1120 to 2660 A were scanned, but no stellar signal was detected in any wavelength interval. This result is consistent with both components of the binary being normal A2A stars. UV variability or a source other than HR 4453 must be invoked to explain the observations of Crawford et al.

Polidan, R. S.↗
NASA NTRS1980

Colors and magnitudes predicted for high redshift galaxies

Ultraviolet observations of nearby galaxies with the ANS are used to derive ultraviolet spectra for different galaxy types. These spectra are used with existing visible spectrophotometry to calculate K-corrections, and to predict colors and magnitudes for various galaxy types as a function of redshifts, to z = 2. No evolutionary effects are considered. It appears that the first-ranked cluster galaxies on blue emulsions should be spirals for z greater than or approximately equal to 0.5.

Coleman, G. D.↗
NASA NTRS1981

The Johns Hopkins Ultraviolet Telescope for Shuttle astronomy

The Hopkins Ultraviolet Telescope (HUT) is a 90-cm f/2 prime focus telescope and spectrometer with a photon-counting microchannel plate detector designed to obtain moderate resolution (wavelength interval, approximately 4 A) spectrophotometry of faint (visual magnitude, less than approximately 17) objects in the far-ultraviolet spectral region (approximately 900-1700 A). The HUT will be mounted on the Spacelab Instrument Pointing System and will be operated by a Payload Specialist using a field acquisition TV system to assist in locating targets. The initial flight of the HUT, expected in 1984 or 1985, will be devoted primarily to the study of quasars and active galactic nuclei, emphasizing the 900-1200 A spectral region which is inaccessible with other existing or currently planned orbiting instruments.

Davidson, A. F.↗
NASA NTRS1981

Spectropolarimetry and the physical structure of proto-planetary nebulae

Optical spectropolarimetry and spectrophotometry are presented of the two bipolar nebulae GL 618 and M2-9. A comparison of the polarization in the emission lines and the continuum is used to construct geometrical and physical models for each object. It is found that the forbidden lines arise largely in the visible nebulae, whereas the permitted lines are formed in a central high-density region and are scattered with the stellar continuum by dust grains in the lobes. Condensations are found to be an important component of the lobes, reinforcing the view that these bipolars represent a very early phase in the life of a planetary nebula.

Schmidt, G. D.↗
NASA NTRS1981

Studies of bipolar nebulae. VII - The exciting star of OH 0739-14 /equals OH 231.8 plus 4.2/

A spectral classification for the exciting star of the bipolar reflection nebula OH 0739-14, which has also been observed to be an OH/H2O maser source, is obtained from the spectrum of the nebulosity in the range 6000-9000 A. Spectrophotometry of the visible nebula was obtained with the Cassegrain image-tube scanner on the Lick Observatory 3-m telescope at a resolution of approximately 7 A. The red spectrum is found to be distinguished by TiO absorption at the bandheads at 8206, 8303, 8432, 8442 and 8452 A and VO in the 7400 and 7900 A regions. On the basis of the depths of these bandheads and the K I 7699 A and Ca II infrared triplet, OH 0739-14 is determined to be of spectral type M9 III. The underlying star thus represents the coolest known star to occur in a bipolar system.

Cohen, M.↗
NASA NTRS1981

IUE observations of eight dwarf novae - A study of the outburst cycle from 0.12 to 3.5 microns

The dwarf novae are a class of close binary systems with a G-M star transferring mass to a white dwarf. The transferred material accumulates in a disk and accretes onto the white dwarf. Dwarf novae are characterized by outbursts on time scales of weeks to months possibly triggered by instabilities in the disk. To test the steady state models and the behavior of the disk at various stages of the outburst cycle, IUE observations were conducted for eight dwarf novae. Selected UV continuum points were joined to nonsimultaneous optical and IR spectrophotometry and broad-band photography to yield flux distributions over a large wavelength range. These flux distributions are discussed in terms of available accretion disk models.

Szkody, P.↗
NASA NTRS1981

A spectroscopic, photometric, and magnetic study of the starspot on II Pegasi

A description is presented of extensive observations of II Peg during 1977 and 1978, taking into account multicolor broad-band photometry, high-dispersion spectroscopy, low-dispersion spectrophotometry, and Zeeman analysis. During this time the star showed periodic light variations in excess of a 0.4 mag range attributable to the presence of a large starspot or an equivalent nonuniform surface brightness distribution. The high-precision multicolor photometry, which differed greatly from previous photometric results, illustrates that the starspots on II Peg are continually evolving on time scales of approximately 1 year or less. A low-dispersion spectrum of the large spot showed pronounced VO and TiO molecular adsorption features. A high-resolution, high signal-to-noise Reticon spectrum at lambda 6707 does not show any compelling evidence of previously reported lithium in this star.

Vogt, S. S.↗
NASA NTRS1981

Stepanian's star - The energy distribution reveals a nontypical cataclysmic variable

Einstein, IUE, optical multichannel spectrophotometry, and IR observations of Stepanian's star are discussed in terms of other known cataclysmics. While the X-ray flux and IUE emission-line data are similar to that of dwarf novae, the total continuum flux distribution from uv-IR is cooler (peaking near a 10,000 K blackbody) and is unlike either a stellar component or a classic steady-state disk. The IR data show no evidence for a late-type component.

Szkody, P.↗
NASA NTRS1981

Optical spectral variability of the N galaxies 3C 382 and 3C 390.3

Multichannel spectrophotometry data acquired from 1969 to 1980 are used to study the absolute energy distribution and emission line variability of the N galaxies 3C 382 and 3C 390.3. It is shown that: (1) the continuum spectra can be decomposed into a nuclear nonthermal component of constant spectral shape and a constant elliptical galaxy component; (2) apparent visual magnitudes within a 10 arcsec aperture are derived for underlying galaxies, 3C 382 being 15.27 and 3C 390.3, 16.04; (3) forbidden lines and narrow Balmer lines do not change with the central continuum, but (4) the intensity variations of the broad Balmer lines are correlated nonlinearly with changes in the luminosity of the central continuum source. This correlation can be explained by a time-lag effect if there are two components of broad-line emission, one varying on a time scale of a few months and the other over a few years.

Yee, H. K. C.↗
NASA NTRS1982

Introducing the B stars

Methods for classifying B stars in the visible region by examining low reslution spectra; broadband colors; intermidiate band colors and H beta; absolute magnitude as a function of H beta and H gamma strength and of luminosity class; and the BCD system and its relation to the MK system are examined. The use of OAO-2 spectrophotometry; objective prism and objective grating spectra; and observations from the TD1 satellite for classifying B stars in the ultraviolet region are also discussed. Infrared and radio observations of these stars are reviewed as well as information available concerning masses, radii and velocity of escape.

Source record↗
NASA NTRS1981

Broad band X-ray telescope (BBXRT)

An approach along with corroborating measurements for significantly enhancing the potential of Si(Li) spectrophotometry in X-ray astronomy is presented. The key new element is an unconventional X-ray mirror that meets qualifications of low cost, light weight, and large throughput over a broad energy band at moderate angular resolution. The potential for other applications is also discussed.

Serlemitsos, P. J.↗
NASA NTRS1982

Spectroscopy of Triton and Pluto: Current status and prospects

Near-infrared spectrophotometry of Triton and Pluto at low spectral resolution and signal precision reveals methane absorption on both bodies. The absorption on Triton is probably gaseous CH4, while that on Pluto is a combination of gas and ice of CH4. Using present detectors and telescopes, spectra of Triton and Pluto can be obtained which are 5-10 times better than those published, but such data will not be sufficient to distinguish between gaseous and solid methane on these bodies.

Cruikshank, D. P.↗