Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “spectrophotometry”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

High resolution spectrophotometry of selected features in the 1.1 micron spectrum of Comet Kohoutek /1973f/

Fabry-Perot interferometry of Comet Kohoutek (1973f) at 1.1 microns with a resolution of 1.2 A showed emission features identified as OH and CN lines in addition to a strong Fraunhofer continuum. Central intensities have been derived for three cases (uniform, Gaussian, and Gaussian plus inverse-rho law) of brightness profiles in the comet coma. Limits for CH4, H2O, HeI, SiI and CrI are also derived.

Meisel, D. D.↗
NASA NTRS1975

Spectrophotometry of faint cluster galaxies and the Hubble diagram - An approach to cosmology

New spectrophotometric data are presented for large-redshift galaxies in clusters. A new approach to aperture corrections and the analysis of the Hubble diagram is outlined, including the explicit incorporation of evolutionary effects. The importance of selection effects on the usual methods of analysis are in principle overcome in the analysis, although the heterogeneity of the sample still makes conclusions about cosmology slightly suspect. Formal values of the deceleration parameter are derived under several sets of assumptions, yielding results between +0.33 and -1.27 with formal standard deviations of order 0.7.

Gunn, J. E.↗
NASA NTRS1974

Spectrophotometry of supernovae

Studies were made of a type II supernova (SN 1970g in M 101) and a type I supernova (SN 1972e in NGC 5253) covering the wavelength range from 3200 to 10,000 A. The absolute spectral energy distributions show that both types have a continuum that varies slowly and uniformly with time and carries the bulk of the radiated flux at early epochs. Some lines in both types have P Cygni profiles: broad emissions with broad absorptions at their violet edges. Some lines are common to both types and persist throughout the evolution of the spectrum.

Kirshner, R. P.↗
NASA NTRS1975

Photoelectric spectrophotometry of Wolf-Rayet stars

Photoelectric spectrum scans of five southern Wolf-Rayet stars in the spectral range 4600-4720 A were analyzed to study the variability of brightness and of emission line strengths. No variations of any kind in short time scale were found. However, in WC stars night-to-night variations of 3 to 4 per cent were detected in the emission line strengths.

Bahng, J. D. R.↗
NASA NTRS1975

Near-infrared spectrophotometry of Titan

Several unusual features in the near-IR spectrum of Titan are examined. Observations during four apparitions establish the reality of the S(1) absorption at 8150.7 A, but the existence of the S(O) absorption at 8272.7 A will require further sightings to become definitively established. These two features are particularly important, as they bear on the abundance of H2 in Titan's atmosphere.

Trafton, L. M.↗
NASA NTRS1975

Absolute spectrophotometry in M31 and M32

For a number of places in the bulge of M31, and for two places in M32, photometric scans from lambda = 3300 A to lambda = 10,600 A have been obtained with the multichannel spectrometer on the 5-m Hale telescope. The scans show that in both objects the color temperature (particularly shortward of 5000 A) decreases toward the center, and that the strength of the CN bands increases toward the center in both objects, in agreement with other earlier observations. The new data can all be interpreted in terms of an increase of heavy-element abundance toward the center in both objects by a factor probably less than 2, and by an excess of heavy elements in M31 compared with M32 by a factor probably greater than 2, in qualitative agreement with earlier conclusions of other observers.

Oke, J. B.↗
NASA NTRS1975

Spectrophotometry of CRL 2688 from 2 to 24 microns

Infrared spectrophotometric observations (2 to 24 microns) are reported for CRL 2688, an IR source in Cygnus associated with twin symmetric reflection nebulae. The entire spectrum from 3 to 24 microns is shown to be a generally featureless continuum and to be too broad to be fit by a single blackbody. No evidence is found for ice absorption near 3.1 microns, and the data suggest a possible emission feature near 3.3 microns.

Forrest, W. J.↗
NASA NTRS1975

Evidence for an elemental sulfur component of the clouds from Venus spectrophotometry

The decrease in the reflectivity of Venus in the near-UV can be explained if the clouds contain particles of elemental sulfur in addition to sulfuric acid. The low-resolution McDonald-Pittsburgh spectrum can be fitted by two sulfur-containing, multiple-scattering cloud models: (1) a mixed cloud consisting of one particle of elemental sulfur of radius 10 microns for every 670 particles of sulfuric acid of radius 1 micron, and (2) a layered cloud of optical thickness tau = 1.0 consisting of one-micron particles of sulfuric acid overlying a thick cloud of elemental sulfur particles of radius 3.6 microns. Some of the sulfur is incompletely polymerized. The source of the sulfur is photo-dissociation of COS, although some may also be recycled from the lower atmosphere. The sulfur plays a crucial role in the planetary meteorology of Venus since it is responsible for the bulk of the absorption of solar energy.

Hapke, B.↗
NASA NTRS1976

Spectrophotometry of comet Kohoutek (1973f) during pre-perihelion period

Scans of the head of comet Kohoutek obtained during the pre-perihelion period with a photoelectric spectrum scanner are discussed. The mean relative flux distributions and the continuum energy distribution of the head of comet Kohoutek are given and normalized to 479 nm. The emission features of CN, C3, Ch, and the principal Swan band sequences of C2 and Na are identified and discussed. The adopted monochromatic values relative to 479 nm are given and plotted along with the energy distribution of the sun.

Babu, G. S. D.↗
NASA NTRS1976

Optical pulsations in HZ Herculis. 5. Pulse-resolved spectrophotometry

Digital spectra of HZ Herculis were obtained with 10 A resolution in the 3,600 - 6,000 A region, synchronously dividing the 1.24-s optical pulsation period into eight 155-ms phase bins. The optical pulses are detected in the data, but their fractional amplitude is only 0.08 percent, a factor of 4 less than typically observed. The separate spectra of each one-eighth of the pulse are identical to within the statistics of the observation. If the X-ray to optical pulse reprocessing mechanism concentrates the optical pulsations into discrete spectral line features, data require the pulses to be distributed among more than four such lines.

Margon, B.↗
NASA NTRS1976

Spectrophotometry of the unusual optical candidate for 3U 1728-24 (=GX 2+5 = GX 1+4) a recurrent nova?

The spectrum of the object suggested as a possible optical counterpart of GX 2+5, was studied, using the image tube scanner attached to the 3-m telescope of Lick Observatory. An improved X-ray error box obtained with Copernicus strongly supports this proposed identification. The candidate displays all the characteristics of the symbiotic stars and the related recurrent novae. The spectrum reveals the presence of an M star together with a blue component and a large number of emission lines displaying a wide range of ionization. There is evidence of variability of both the continuum and the line intensities. This object provides strong support for the often proposed association of some X-ray sources with nova-like systems.

Davidsen, A. F.↗
NASA NTRS1975

Spectrophotometry of Comet Kohoutek /1973f = 1973XII/

Spectrum scans have been obtained of Comet Kohoutek with a Fourier spectrometer at heliocentric distances from 0.55 to 1.05 AU. The useful spectral range is roughly 3800-8400 A and the resolution is about 10-15 A at 5000 A. Large variations occurred in the gas-to-dust ratio (pre- versus postperihelion) and in the relative strength of the NH2 bands (with heliocentric distance). There is a smaller change in the ratio of CN to C2 emission. The Swan bands of C2 show the customary anomaly in strengths implying highly non-Boltzmann distributions among vibrational levels. The red and violet CN system fluxes are in slightly better agreement with laboratory data on oscillator strengths than results on previous comets. Other species measured include Na, (O I), CH, and C3.

Ahearn, M. F.↗
NASA NTRS1975

Ultraviolet photometry and spectrophotometry of Algol

OAO-2 blue and UV light curves and spectrophotometric observations are used to establish effective temperatures and luminosities for the three components of the eclipsing Algol (beta Persei) system. An essentially complete energy distribution is given for Algol, and the fundamental properties - geometrical quantities, wavelength-dependent quantities and derived astrophysical quantities - are presented for the star.

Eaton, J. A.↗
NASA NTRS1976

Optical and infrared spectrophotometry of 18 Markarian galaxies

Slit spectra, spectrophotometric scans, and infrared broad-band observations are presented for 18 Markarian galaxies with emission lines. Eight of the program galaxies can be classified as Seyfert galaxies. Arguments are given that thermal, nonthermal, and stellar radiation components are present. Broadly speaking, one group of Seyfert galaxies is characterized both by the presence of a high-density region of gas and by a continuum dominated by nonthermal radiation. The continua of the remaining program Seyferts, which do not have a high-density region of gas, are dominated by thermal radiation from dust and a stellar continuum. The 10 galaxies which are not Seyfert galaxies are shown to be examples of extragalactic H II regions; there is evidence for thermal emission from dust being present at 10 microns in four of these galaxies.

Neugebauer, G.↗
NASA NTRS1976

Spectrophotometry and UBVRI photometry of Eros

Spectrophotometric and broad-band photoelectric observations of Eros are reported. No existing meteorite spectrum matches the asteroid data directly. Assemblages of iron or stony-iron with ordinary-chondrite material generate the best match for the reflectivity curve of Eros. Variability was found in the 0.6 micron band and V-R and V-I colors.

Wisniewski, W. Z.↗
NASA NTRS1976

Spectrophotometry /0.33 to 1.07 microns/ of 433 Eros and compositional implications

The spectral reflectance (0.33-1.07 micrometers) for the asteroid 433 Eros was determined as a function of rotational phase during January 28-30, and February 15, 1975. Interpretation of absorption features suggests Eros is composed of an undifferentiated assemblage of moderate to high temperature minerals (iron, pyroxene, and olivine, but no carbon). H-type ordinary chondrites are such assemblages, but it would be premature to conclude that Eros is like an H chondrite meteorite in composition until a better understanding is reached of possible physical differences between laboratory powders and asteroid regoliths for metal-bearing assemblages. There are no large-scale major compositional variations on the different sides of Eros.

Pieters, C.↗