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4.0
Jul 26, 2019
07/19
by
Pottasch, Stuart R. (Stuart Robert), 1932-
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ix, 322 p. : 25 cm. --
Topic: Planetary nebulae
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38
Sep 16, 2011
09/11
by
Kwok, S. (Sun)
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Includes bibliographical references (p. [169]-170) and index
Topic: Planetary nebulae
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0.0
Dec 15, 2020
12/20
by
Viktor Viktorovich Sobolev, Sergei Illarionovich Gaposchkin
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Scan of book Moving envelopes of stars by Viktor Viktorovich Sobolev b19150902 d19990107 [] translated by Sergei Illarionovich Gaposchkin b18980729 d19841017 [1960] {523.87--oclc} No compiled version
Topics: Variable Stars, Planetary Nebulae
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34
Dec 12, 2016
12/16
by
P.J. Storey, Taha Sochi, N.R. Badnell
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We present electron collision strengths and their thermally averaged values for the forbidden lines of the astronomically abundant doubly-ionized oxygen ion, O^{2+}, in an intermediate coupling scheme using the Breit-Pauli relativistic terms as implemented in an R-matrix atomic scattering code. We use several atomic targets for the R-matrix scattering calculations including one with 72 atomic terms. We also compare with new results obtained using the intermediate coupling frame transformation...
Topics: Atomic physics, astronomy, oxygen, planetary nebulae, Optical lines, Infrared lines
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353
Jun 21, 2010
06/10
by
Tunnell, P. J
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No Abstract Available
Topics: ANDROMEDA CONSTELLATION, PLANETARY NEBULAE, SPECTROPHOTOMETRY, ATOMIC EXCITATIONS, ELECTRON DENSITY...
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284
May 26, 2011
05/11
by
Barnes, Aaro
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The quadrennium 1975-1978 was a period of great advance for solar-wind studies, a period that combined exploration of new regions with increased maturity in established fields of study. The Helios, Pioneer, and Voyager spacecraft have been exploring the inner and outer regions of the solar wind. There has been a rebirth of the study of possible relations between solar variability and Earth's climate and weather, stimulated largely by Eddy's investigation of the Maunder Minimum; the solar wind...
Topics: ORBITAL RESONANCES (CELESTIAL MECHANICS), PERTURBATION, SOLAR CORONA, PROTOPLANETS, PLANETARY...
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4.1K
Jul 21, 2010
07/10
by
NON
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A compilation of 40 technical reports on research conducted by participants in the 1985 NASA/ASEE Summer Faculty Fellowship Program at Marshall Space Flight Center (MSFC) is given. Weibull density functions, reliability analysis, directional solidification, space stations, jet stream, fracture mechanics, composite materials, orbital maneuvering vehicles, stellar winds and gamma ray bursts are among the topics discussed.
Topics: COSMIC DUST, PLANETARY NEBULAE, SPECTROPHOTOMETRY, ASTRONOMICAL SPECTROSCOPY, CARBON, FAR INFRARED...
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7.3K
movies
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A montage of recent NASA imagery including the STS121 Shuttle launch, photos from the Spirit Rover on Mars, repairs to the International Space Station, Hubble Telescope photos of planetary nebulae, repairs to the Hubble Telescope using space walks and a robotic arm, pictures from the Mars Reconnaissance Orbiter, the Messenger mission to Mercury, and NASA's planned nuclear powered space engine to be used in exploring the moons of Jupiter.
Topics: nasa, mars, shuttle, space, jupiter, mercury, space station, callisto, ganymede, europa, planetary...
671
671
Jun 13, 2011
06/11
by
Leidecker, Henning; Brusse, Ja
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This viewgraph presentation reviews the history of tin and other metal whiskers, and the damage they have caused equipment. There are pictures of whiskers on various pieces of electronic equipment, and microscopic views of whiskers. There is also a chart with information on the documented failures associated with metal whiskers. There are also examples of on-orbit failures believed to be caused by whiskers.
Topics: PLANETARY NEBULAE, EMITTANCE, X RAY IMAGERY, K LINES, IMAGING SPECTROMETERS, HELIUM, X RAYS,...
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576
May 30, 2011
05/11
by
Thompson, Milton O.; Hunley, J. D
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The document by Milt Thompson that is reproduced here was an untitled rough draft found in Thompson's papers in the Dryden Historical Reference Collection. Internal evidence suggests that it was written around 1974. I have not attempted to second guess what Milt might have done in revising the paper, but I have made some minor stylistic changes to make it more readable without changing the sense of what Milt initially wrote. For the most part, I have not attempted to bring his comments up to...
Topics: PLANETARY NEBULAE, ABUNDANCE, NEAR ULTRAVIOLET RADIATION, PHOTOIONIZATION, ELECTRON ENERGY, HIGH...
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308
May 23, 2011
05/11
by
Garetto, Lawrence P.; Roberts, W. Eugen
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Previous methods of identifying cells undergoing DNA synthesis (S-phase) utilized H-3 Thymidine (3HT) autoradiography. 5-Bromo-2'-deoxyuridine (BrdU) immunohistochemistry is a nonradioactive alternative method. This experiment compared the two methods using the nuclear volume model for osteoblast histogenesis in two different embedding media. Twenty Sprague-Dawley rats were used, with half receiving 3HT (1 micro g Ci/g) and the other half BrdU (50 micro g/g). Condyles were embedded (one side in...
Topics: HYDROGENATION, INFRARED RADIATION, POLYCYCLIC AROMATIC HYDROCARBONS, MOLECULES, PLANETARY NEBULAE,...
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92
Dec 12, 2016
12/16
by
P.J. Storey, Taha Sochi
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The continuum spectrum of the planetary nebula Hf 2-2 close to the Balmer discontinuity is modeled in the context of the long standing problem of the abundance and temperature discrepancy found when analyzing optical recombination lines and collisionally excited forbidden lines in nebulae. Models are constructed using single and double Maxwell-Boltzmann distributions as well as kappa-distributions for the energies of the free electrons. New results for the necessary continuum and line emission...
Topics: Atomic physics, astronomy, planetary nebulae, Hf 2-2, Continuum Emission, Balmer Limit, ORL versus...
1,146
1.1K
Jul 26, 2010
07/10
by
NON
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No Abstract Available
Topics: ABUNDANCE, OXYGEN, PLANETARY NEBULAE, HELIUM, MAGNESIUM ISOTOPES, NEON ISOTOPES, STELLAR...
Spectrophotometric observations of emission line intensities were made in seven positions in the planetary nebula NGC 6853; for five of the positions, coverage is across the entire spectral range 1400A to 9600A. Standard equations used to correct for the existence of elements in other than the optically-observable ionization stages give results over a wide range of ionization that are generally consistent and in agreement with abundances calculated using ultraviolet lines. As in the previous...
Topics: NASA Technical Reports Server (NTRS), IONIZATION, PLANETARY NEBULAE, SPECTROPHOTOMETRY, EXCITATION,...
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55
Apr 12, 2017
04/17
by
Taha Sochi
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We present the results of a calculation of recombination coefficients for O^{2+} + e^- using an intermediate coupling treatment that fully accounts for the dependence of the distribution of population among the ground levels of O^{2+} on electron density and temperature. The calculation is extended down to low electron temperatures where dielectronic recombination arising from Rydberg states converging on the O^{2+} ground levels is an important process. The data, which consist of emission...
Topics: Atomic Physics, Astrochemistry, Planetary Nebulae, H II regions, Astronomy, Astrophysics, O II...
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69
Dec 12, 2016
12/16
by
P.J. Storey, Taha Sochi
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We present effective collision strengths for electron excitation and de-excitation of the ten forbidden transitions between the five lowest energy levels of the astronomically abundant doubly-ionised oxygen ion, O^{2+}. The raw collision strength data were obtained from an R-matrix intermediate coupling calculation using the Breit-Pauli relativistic approximation published previously by the authors. The effective collision strengths were calculated with kappa-distributed electron energies and...
Topics: Atomic physics, astronomy, planetary nebulae, oxygen, effective collision strength,...
A set of cooled filter wheel spectrometers covering the wavelength range 2.8-24 micron have been constructed and tested. The two short wavelength systems (2.8-5.6 micron and 7-14 micron) have been found to be very useful and provide a substantial increase in signal to noise over previous systems. The 12-24 micron system, although still very useful, suffers from a low transmittance filter wheel and possibly poor wavelength resolution, intrinsic to the filter wheel.
Topics: NASA Technical Reports Server (NTRS), ASTRONOMICAL SPECTROSCOPY, FILTER WHEEL INFRARED...
The following subject areas are covered: (1) magnetization of meteorites; (2) the possible origin of a nebular magnetic field; (3) the possibility of magnetic flares; (4) external manifestations; (5) dynamical effects of the magnetic fields; and (6) the problem of ionization.
Topics: NASA Technical Reports Server (NTRS), MAGNETIC FIELDS, MAGNETOHYDRODYNAMICS, PLANETARY NEBULAE,...
A planetesimal moving in the Solar Nebula experiences an aero- dynamic drag which causes its orbit to circularize and shrink. However, resonant perturbations from a protoplanet interior to the planetesimal's orbit ran counteract both the orbital decay and the damping of the eccentricity: the planetesimal can be captured into an orbital resonance and its eccentricity pumped up to a modestly high equilibrium value. Thus, orbital resonances constitute (partial) barriers to the delivery of...
Topics: NASA Technical Reports Server (NTRS), ORBITAL RESONANCES (CELESTIAL MECHANICS), PERTURBATION, SOLAR...
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180
May 31, 2011
05/11
by
Leitner, Jesse; Quinn, Davi
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As part of NASA's endeavor to push the envelope and go where we have never been before, the Space Science Enterprise has laid out a vision which includes several missions that revolutionize the collection of scientific data from space. Many of the missions designed to meet the objectives of these programs depend heavily on the ability to perform space-based interferometry, which has recently become a rapidly growing field of investigation for both the scientific and engineering communities....
Topics: PLANETARY NEBULAE, NITROGEN, HELIUM, ULTRAVIOLET SPECTRA, INFRARED SPECTRA, ELECTRON DENSITY...
Small but macroscopic particles - chondrules, higher temperature mineral inclusions, metal grains, and their like - dominate the fabric of primitive meteorites. The properties of these constituents, and their relationship to the fine dust grains which surround them, suggest that they led an extended existence in a gaseous protoplanetary nebula prior to their incorporation into their parent primitive bodies. In this paper we explore in some detail the velocities acquired by such particles in a...
Topics: NASA Technical Reports Server (NTRS), CHONDRULE, TURBULENCE, METEORITES, MINERALS, PLANETARY...
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277
Jul 26, 2010
07/10
by
Maddalon, Dal V.; Braslow, Albert L
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The effectiveness and practicality of candidate leading edge systems for suction laminar flow control transport airplanes were investigated in a flight test program utilizing a modified JetStar airplane. The leading edge region imposes the most severe conditions on systems required for any type of laminar flow control. Tests of the leading edge systems, therefore, provided definitive results as to the feasibility of active laminar flow control on airplanes. The test airplane was operated under...
Topics: CHEMICAL EVOLUTION, PLANETARY NEBULAE, SOLAR SYSTEM, TEMPERATURE PROFILES, COMET NUCLEI, COMETS,...
NASA Ames Research Center is one of NASA s oldest centers, having started out as part of the National Advisory Committee on Aeronautics, (NACA). The site, about 40 miles south of San Francisco, still houses many wind tunnels and other aviation related departments. In recent years, with the growing realization that space exploration is heavily dependent on computing and data analysis, its focus has turned more towards Information Technology. The Computational Sciences Division has expanded...
Topics: NASA Technical Reports Server (NTRS), BAYES THEOREM, AUTONOMY, MACHINE LEARNING, PLANETARY NEBULAE,...
New optical spectrophotometric observations of emission-line intensities have been made in eight positions in the Ring Nebula corresponding to those observed previously with the Ultraviolet Explorer satellite; the total coverage is therefore 1400 to 7200 A. The intensities are in generally good agreement with those found previously in corresponding positions. The 0(++) and Balmer continuum electron temperatures agree well on the average and, like the N(+) electron temperatures, decrease with...
Topics: NASA Technical Reports Server (NTRS), EMISSION SPECTRA, IONIZATION, LINE SPECTRA, OBSERVATION,...
The following topics are covered in the presented papers: (1) producing chondrules; (2) carbons, CAI's, and chondrules; (3) large scale processes in the solar nebula; (4) chondrule-matrix relationships in chondritic meteorites; (5) overview of nebula models; (6) constraints placed on the nature of chondrule precursors; (7) turbulent diffusion and concentration of chondrules in the protoplanetary nebula; (8) heating and cooling in the solar nebula; (9) crystallization trends of precursor...
Topics: NASA Technical Reports Server (NTRS), CARBON, CHONDRITES, CHONDRULE, CONFERENCES, METEORITES,...
During the current reporting period we have continued our studies of the dissociative recombination (DR) of HeH(+) with an electron with the goal of calculating accurate cross sections and rate coefficients to allow for the accurate modelling of the abundance of HeH(+) in planetary nebulae and supernova envelopes. We have also started studies of the DR of H3(+), a process of great importance in the interstellar medium.
Topics: NASA Technical Reports Server (NTRS), INTERSTELLAR MATTER, NUMERICAL ANALYSIS, HELIUM COMPOUNDS,...
Chemical and physical models of the Jovian subnebula are addressed. Halide cloud condensation and volatile element inventories on Venus and considered. Computation methods for isolated grain condensation behavior are examined.
Topics: NASA Technical Reports Server (NTRS), CHEMICAL CLOUDS, HALIDES, JUPITER (PLANET), PLANETARY...
Some carbon-rich planetary nebulae exhibit a strong broad emission feature beginning at Lambda which is approximately 24 microns and extending to Lambda greater than 30 microns. Thirty to 55 micron spectrophotometry of Ic 418 and NGC 6572, both of which have the strong broad emission feature, allow the wavelength dependence of the emissivity of the dust responsible for the feature to be defined. Comparison with laboratory spectra of candidate materials which are likely to condense in a...
Topics: NASA Technical Reports Server (NTRS), COSMIC DUST, PLANETARY NEBULAE, SPECTROPHOTOMETRY,...
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140
May 28, 2011
05/11
by
Fritzsch, Bernd; Bruce, L. L
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In our original application we proposed to investigate the effects of gravity on the formation of connections between the gravity receptors of the ear and the brain in rat pups raised in space beginning at an age before these connections are made until near the time of birth, when they are to some extent functional. We used the neuronal tracer, Dil, which could be applied to tissue obtained immediately after landing of the space shuttle, thus minimizing changes due to the earth's gravity. We...
Topics: ORION NEBULA, STUDENTS, EDUCATION, PLANETARY NEBULAE, HUBBLE SPACE TELESCOPE, INFRARED SPACE...
Spectrophotometric observations of emission-line intensities over the spectral range 1400 to 7200 A were made in five positions in the planetary nebula NGC 1535. There is some evidence for variation in the Balmer decrements between these positions. The O(++) electron temperature varies little from 11500 K across these positions; the Balmer continuum electron temperature averages a few hundred K higher than this, but this difference is insignificant when compared to the measurement errors. As...
Topics: NASA Technical Reports Server (NTRS), ABUNDANCE, BALMER SERIES, EMISSION SPECTRA, IONIZATION,...
Nine of the planetary nebulae observed by the Wisconsin filter photometers are compared with 15 Monocerotis in the spectral region 1430-4250 A. The data are corrected for the degradation of the filters of stellar photometer number four with time. Comparisons with simple models indicate that most of the observed nebulae are subject to some interstellar extinction in the far ultraviolet. However, NGC 246 and NGC 1360 appear to be nearly unreddened. Thus far no unexpected features have been found...
Topics: NASA Technical Reports Server (NTRS), OAO 2, PLANETARY NEBULAE, ULTRAVIOLET PHOTOMETRY,...
An understanding was sought for the mechanisms of nucleation of refractory materials, and the relative importance of factors controlling the rate of cluster formation and growth for astrophysically important species. The structure and composition of the condensates is being studied, with the goal of characterizing the grains present in the primitive solar nebula.
Topics: NASA Technical Reports Server (NTRS), CONDENSATES, INTERPLANETARY DUST, NUCLEATION, PLANETARY...
A brief summary of the research highlights is presented. The topics covered include the following: binary nuclei of planetary nebulae; other variable planetary nuclei; low-mass supergiants; and other IUE-related research.
Topics: NASA Technical Reports Server (NTRS), BINARY STARS, PLANETARY NEBULAE, STELLAR ENVELOPES, STELLAR...
The molecular component of the mass outflow at high resolution was mapped with the Owens Valley Millimeter-Wave Interferometer in two well-known objects, CRL 2688 and CIT 6. Interferometric observations of a pair of carbon stars which are evolving toward the planetary nebula stage have revealed evidence of episodic, nonspherically symmetric mass loss, and may lead to a fuller understanding of shielding properties of the dust grains involved in these flows.
Topics: NASA Technical Reports Server (NTRS), CARBON STARS, LOSSES, MAPPING, PLANETARY NEBULAE, STELLAR...
A detailed study of the effects of gravitational radiation on the relative positions of objects was carried out with the hope that astrometric detection of gravitational radiation might be possible. The results are discouraging. It would appear that narrow-field instruments in the Astrometric Telescope Facility (ATF) class are still several orders of magnitude less accurate than would be required for this very delicate kind of measurement. However, the situation changes considerably when...
Topics: NASA Technical Reports Server (NTRS), ASTROMETRY, GRAVITATIONAL WAVES, INTERFEROMETERS, QUASARS,...
Spectrophotometric observations of emission-line intensities over the spectral range 1400 to 1700 A were made in seven positions in the planetary nebulae NCG 6826. The O(++) electron temperature varies little from 8900 K throughout the nebula; the Balmer continuum electron temperature averages 1500 K higher. The wavelength 4267 C II line intensities imply C(++) abundances that are systematically higher than those determined from the wavelength 1906, 1909 C III lines, but because of...
Topics: NASA Technical Reports Server (NTRS), ABUNDANCE, EMISSION SPECTRA, IONIZATION, LINE SPECTRA,...
Spectrophotometric observations of emission-line intensities over the spectral range 1400 to 7200 A were made in six positions in the planetary nebula NGC 2392. Standard equations used to correct for the existence of elements in other than the optically observable ionization stages give consistent results for the different positions that are in excellent agreement with abundances calculated using ultraviolet lines, and there is no evidence for any abundance gradient in the nebula. The...
Topics: NASA Technical Reports Server (NTRS), ABUNDANCE, EMISSION SPECTRA, INTERSTELLAR CHEMISTRY,...
The program's goal was to understand the physics underlying the [O III] (lambda)5007 planetary nebula luminosity function (PNLF) and evaluate its accuracy as an extragalactic distance indicator. Work under the grant concentrated in two areas. The first major goal was to extensively test the PNLF method to find its limits. We did this performing yet another internal test of the method in the core galaxies of the Fornax Cluster, performing external comparisons of PNLF distances with distances...
Topics: NASA Technical Reports Server (NTRS), RESEARCH, PLANETARY NEBULAE, LUMINOSITY, H II REGIONS,...
The AstroBiology Explorer (ABE) mission concept consists of a dedicated space observatory having a 60 cm class primary mirror cooled to T < 50 K equipped with medium resolution cross-dispersed spectrometers having cooled large format near- and mid-infrared detector arrays. Such a system would be capable of addressing outstanding problems in Astrochemistry and Astrophysics that are particularly relevant to Astrobiology and addressable via astronomical observation. The mission s...
Topics: NASA Technical Reports Server (NTRS), MOLECULAR CLOUDS, ORGANIC COMPOUNDS, EXOBIOLOGY, PLANETARY...
In this program, we used the IRAS database to identify and study proto-planetary nebulae (PPNs), objects in transition from the asymptotic giant branch (AGB) to the planetary nebula (PN) phase. Such objects radiate predominately in the mid-infrared 10-30 micrometer region, due to emission from warm (150-300 K) circumstellar dust. We used the IRAS database to identify 55 objects whose fluxes peak in the IRAS 25 micrometer band and which are associated with visible stars. We combined IRAS and...
Topics: NASA Technical Reports Server (NTRS), PLANETARY NEBULAE, INFRARED ASTRONOMY SATELLITE, DUST,...
353
353
Jul 26, 2010
07/10
by
NON
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The scientific research and supporting technology development conducted in the Space Life Sciences Program is described. Accomplishments of the past year are highlighted. Plans for future activities are outlined. Some specific areas of study include the following: Crew health and safety; What happens to humans in space; Gravity, life, and space; Sustenance in space; Life and planet Earth; Life in the Universe; Promoting good science and good will; Building a future for the space life sciences;...
Topics: ASTRONOMICAL MODELS, CONFERENCES, MASS DISTRIBUTION, PLANETARY ATMOSPHERES, PROTOPLANETS, U.S.S.R.,...
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273
May 26, 2011
05/11
by
Lollar, Louis F.; Maus, Louis C
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Marshall Space Flight Center (MSFC) is the National Aeronautics and Space Administration's (NASA) lead center for space transportation systems development. These systems include earth to orbit launch vehicles, as well as vehicles for orbital transfer and deep space missions. The tasks for these systems include research, technology maturation, design, development, and integration of space transportation and propulsion systems. One of the key elements in any transportation system is the...
Topics: BINARY STARS, TRAJECTORIES, STELLAR WINDS, MASS TRANSFER, ASYMPTOTIC GIANT BRANCH STARS, STELLAR...
Infrared spectroscopy was used to detect many forbidden fine structure emission lines in planetary nebulae. Measurements of these lines offer sensitive probes of the physical conditions and ionization structure, and lead to improved abundance determinations.
Topics: NASA Technical Reports Server (NTRS), EMISSION SPECTRA, FINE STRUCTURE, INFRARED SPECTRA, LINE...
Spectrophotometric observations of emission-line intensities over the spectral range 1400 to 7200 A were made in five positions in the planetary nebula NGC 7662. Standard equations used to correct for the existence of elements in other than the optically observable ionization stages show a consistent and approximate agreement with abundances calculated using ultraviolet lines. The abundances of C and N indicate that some mixing of CNO-processed material into the nebular shell may have occurred...
Topics: NASA Technical Reports Server (NTRS), EMISSION SPECTRA, IONIZATION, LINE SPECTRA, PLANETARY...
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May 24, 2011
05/11
by
Ray, C. S.; Day, D. E.; Huang, W.; Narayan, K. Lakshmi; Cull, T. S.; Kelton, K. F
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The influence of preannealing treatments on the polymorphic crystallization of lithium disilicate glasses is examined. As expected, glasses heated at different rates through the temperature range where there is significant nucleation develop widely different numbers of nuclei. This can dramatically influence the stability and transformation characteristics of the annealed glass. Non-isothermal differential scanning calorimetry (DSC) and differential thermal analysis (DTA) measurements are...
Topics: PHOTODISSOCIATION, ACTIVE GALACTIC NUCLEI, EXCITATION, GAS DENSITY, TIME DEPENDENCE, PHOTONS,...
This paper follows the broadly accepted theory that Oort-Cloud Comets originated in the Solar Nebula in the general region where the major planets, Jupiter and Saturn, were formed while the Kuiper-Belt Comets originated farther out where the temperatures were lower. The Oort-Cloud Comets are identified orbitally by long periods and random inclinations and, including the Halley-type comets, comets with a Tisserand Criterion less than 2.0. Kuiper-Belt comets are identified by short periods,...
Topics: NASA Technical Reports Server (NTRS), OORT CLOUD, COMETS, GRAVITATIONAL FIELDS, PLANETS,...
We have shown earlier that the relative abundance of radiogenic Cr-53 in bulk ordinary chondrites (approximately 0.48 epsilon) is clearly different from that in the earth-moon system (0 epsilon). The SNC parent body (Mars) is characterized by an intermediate Cr-53 excess (approximately 0.23 epsilon). We have also shown that the Mn-Cr systematics of the howardite-eucrite-diogenite parent body (HED PB, the asteroid Vesta) is consistent with the chondritic Mn/Cr ratio in the bulk HED PB and that...
Topics: NASA Technical Reports Server (NTRS), ENSTATITE, HETEROGENEITY, MANGANESE ISOTOPES, PLANETARY...
The following subject areas are covered: (1) the mass distribution; (2) interior models; (3) atmospheric compositions and their implications; (4) heat flows and their implications; (5) satellite systems; (6) temperatures in the solar nebula; and (7) giant planet formation.
Topics: NASA Technical Reports Server (NTRS), GAS GIANT PLANETS, NATURAL SATELLITES, PLANETARY EVOLUTION,...
This report summarizes the final results of an IUE investigation to search for signs of evolutionary changes in high-mass central stars of planetary nuclei, as evidenced by UV-optical fading over the lifetime of the satellite. The program is a continuation of an earlier investigation, expanding the target list to include more types of hot central stars and to obtain more spectra of previously observed stars. In order to compare the IUE fluxes of a central star obtained over a more-than-ten-year...
Topics: NASA Technical Reports Server (NTRS), FADING, HOT STARS, PLANETARY NEBULAE, STELLAR EVOLUTION,...
An ultraviolet spectrum of NGC 7027 was obtained with a rocket-borne telescope. The observed fluxes are given on an absolute basis and upper limits are given for the strongest predicted lines which were not observed. The extinction correction was made on the basis of the observed and calculated line ratios for the hydrogenic recombination line of He 2 at 1640A to H beta. The extinction is in agreement with ground based determinations. When corrected for extinction the C 4 resonance line at...
Topics: NASA Technical Reports Server (NTRS), PLANETARY NEBULAE, ROCKET-BORNE INSTRUMENTS, ULTRAVIOLET...
