Interplanetary dust particles (IDPs) collected in the Earth s stratosphere contain high abundances of submicrometer amorphous silicates known as GEMS grains. From their birth as condensates in the outflows of oxygen-rich evolved stars, processing in interstellar space, and incorporation into disks around new stars, amorphous silicates predominate in most astrophysical environments. Amorphous silicates were a major building block of our Solar System and are prominent in infrared spectra of...
Topics: NASA Technical Reports Server (NTRS), AMORPHOUS MATERIALS, SILICATES, INTERPLANETARY DUST,...
Disk accretion powers many astronomical objects, including pre-main sequence stars, interacting binary systems, and active galactic nuclei. Unfortunately, models developed to explain the behavior of disks and their surroundings - boundary layers, jets, and winds - lack much predictive power, because the physical mechanism driving disk evolution - the viscosity - is not understood. Observations of many types of accreting systems are needed to constrain the basic physics of disks and provide...
Topics: NASA Technical Reports Server (NTRS), PHYSICAL FACTORS, GALACTIC NUCLEI, SYMBIOTIC STARS, VISUAL...
(Omega) Cen contains the largest population of very hot horizontal branch (HB) stars known in a globular cluster. Recent UV observations (Whitney et al. 1998; D'Cruz et al. 2000) show a significant population of hot stars below the zero-age horizontal branch ("blue hook" stars), which cannot be explained by canonical stellar evolution. Stars which suffer unusually large mass loss on the red giant branch and thus experience the helium core flash while descending the white dwarf cooling...
Topics: NASA Technical Reports Server (NTRS), SPECTROSCOPIC ANALYSIS, HORIZONTAL BRANCH STARS, HOT STARS,...
For red giants a smooth increase in the nitrogen to carbon abundance ratio for increasing B-V as is expected for the first dredge up phase when the outer convection zone deepens is found. An average increase in the nitrogen to silicon ratio for B-V = 0.6 which goes back to almost solar values for cool giants with B - V approximately 1.0 is reported. It looks as if Si would be enriched for deeper mixing contrary to expectations from standard evolution theory.
Topics: NASA Technical Reports Server (NTRS), ABUNDANCE, GIANT STARS, IUE, SPACEBORNE ASTRONOMY,...
A growing amount of observational and theoretical evidence suggests that most main sequence stars are surrounded by disks of cometary material. The dust production by comets in such disks is investigated when the central stars evolve up the red giant and asymptotic giant branch (AGB). Once released, the dust is ablated and accelerated by the gas outflow and the fragments become the seeds necessary for condensation of the gas. The origin of the requisite seeds has presented a well known problem...
Topics: NASA Technical Reports Server (NTRS), ASYMPTOTIC GIANT BRANCH STARS, COMETS, CONDENSATION, COSMIC...
An instrument is described which will provide a direct image of gamma-ray line or continuum sources in the energy range 300 keV to 10 MeV. The use of this instrument to study the celestial distribution of the (exp 26)Al isotope by observing the 1.809 MeV deexcitation gamma-ray line is illustrated. The source location accuracy is 2' or better. The imaging telescope is a liquid xenon time projection chamber coupled with a coded aperture mask (LXe-CAT). This instrument will confirm and extend the...
Topics: NASA Technical Reports Server (NTRS), BALLOON FLIGHT, CONSTRUCTION, GAMMA RAY ASTRONOMY, HIGH...
A dating technique for faint, distant star clusters observable in the local group of galaxies with the space telescope is discussed. Color-magnitude diagrams of Magellanic Cloud clusters are mentioned along with the metallicity of star clusters.
Topics: NASA Technical Reports Server (NTRS), MAGELLANIC CLOUDS, STAR CLUSTERS, STELLAR LUMINOSITY, STELLAR...
Red stellar objects for which V-1 was greater than a value of about 2 (supm). 5 were extracted from photographs of 23 program fields. Tabular data for each field show the object name; the 1950 epoch right ascension, declination, galactic longitude, galactic latitude; radial distance from field venter in decimal degrees; color classes; and objects ordered by redness.
Topics: NASA Technical Reports Server (NTRS), ASTRONOMICAL CATALOGS, NEAR INFRARED RADIATION, SKY SURVEYS...
Using HST/GHRS, HST/STIS and FUSE archival data for alpha Tau and the CHIANTI spectroscopic code, we have derived line shifts, volumetric emission measures, and plasma density estimates, and calculated filling factors for a number of UV lines forming between 10,000 K and 300,000 K in the outer atmosphere of this red giant star. The data suggest the presence of low-temperature extended regions and high-temperature compact regions, associated with magnetically open and closed structures in the...
Topics: NASA Technical Reports Server (NTRS), LATE STARS, RED GIANT STARS, GIANT STARS, ATMOSPHERIC...
Most silicate stardust analyzed in the laboratory and observed around stellar environments derives from O-rich red giant and AGB stars [1,2]. Supernova (SN) silicates and oxides are comparatively rare, and fewer than 10 grains from no-va or binary star systems have been identified to date. Very little is known about dust formation in these stellar environments. Mineralogical studies of only three O-rich SN [3-5] and no nova grains have been performed. Here we report the microstructure and...
Topics: NASA Technical Reports Server (NTRS), ASYMPTOTIC GIANT BRANCH STARS, STARDUST MISSION, MINERALOGY,...
The chemical composition of the Crab Nebula is compared with several presupernova models. The small carbon and oxygen abundances in the helium-rich nebula are consistent with only the presupernova model of the star whose main sequence mass was MMS approximately 8-9.5 M. More massive stars contain too much carbon in the helium layer and smaller mass stars do not leave neutron stars. The progenitor star of the Crab Nebula lost appreciable part of the hydrogen-rich envelope before the...
Topics: NASA Technical Reports Server (NTRS), CHEMICAL COMPOSITION, CRAB NEBULA, NEUTRON STARS, SUPERNOVA...
Stars of various types are believed to be the main source of interstellar (IS) dust grans. The most important confirmed source is evolved giant and supergiant stars. Supernovae also contribute to the mass loss. The differences between circumstellar (CS) and IS dust were reviewed using the following topics: alteration of CS dust grains, size distribution, space observation of CS and IS dust, comparison of infrared spectra, isotopic signatures, Magellanic clouds and nearby galaxies, life cycles...
Topics: NASA Technical Reports Server (NTRS), GIANT STARS, INTERSTELLAR MATTER, STELLAR ENVELOPES, STELLAR...
Interstellar dust grains are presumed in part to have their origins in the outer atmospheres of red giant and supergiant stars because, despite the efficiency of shock destruction of grains in the interstellar medium (ISM), meteoritic samples possess isotopic signatures that are consistent with nucleosynthetic origin in the interior of evolved stars. There is ample evidence to suggest that once dust grains form near red giants and supergiants, radiation pressure is sufficient to drive them to...
Topics: NASA Technical Reports Server (NTRS), CHROMOSPHERE, COSMIC DUST, INTERSTELLAR MATTER, RED GIANT...
The research programs are highlighted in the following areas: major planets; planetary satellites and rings; asteroids; comets; dark organic matter; theoretical and analytical structures; extrasolar planetary; and telescopes.
Topics: NASA Technical Reports Server (NTRS), ASTEROIDS, COMETS, GIANT STARS, PLANETOLOGY, RESEARCH AND...
Among warm giant stars, rapid mass loss sets in along a well defined velocity dividing line (VDL). Hot corona also disappear close to the VDL and thermal pressure cannot drive the observed rapid mass loss in these stars. The VDL may be associated with magnetic fields changing from closed to open. Such a change is consistent with the lack of X-rays from late-type giants. A magnetic transition locus based on Pneuman's work on helmet streamer stability agrees well with the empirical VDL. The...
Topics: NASA Technical Reports Server (NTRS), GIANT STARS, MAGNETIC FIELDS, STELLAR MASS EJECTION, STELLAR...
The properties of the chromospheres, transition regions and coronas of cool evolved stars are reviewed based primarily on recent ultraviolet and X-ray studies. Determinations of mass loss rates using new observational techniques in the ultraviolet and radio spectral regions are discussed and observations indicating general atmospheric motions are considered. The techniques available for the quantitative modeling of these atmospheres are outlined and recent results discussed. Finally, the...
Topics: NASA Technical Reports Server (NTRS), GIANT STARS, STELLAR ATMOSPHERES, STELLAR CORONAS, SUPERGIANT...
Ultraviolet studies of various astronomical entities are reported. Among the specific phenomena examined were supernova remnants, dwarf novae, red giant stars, stellar winds, binary stars, and galaxies.
Topics: NASA Technical Reports Server (NTRS), BINARY STARS, DWARF NOVAE, GALAXIES, RED GIANT STARS, STELLAR...
IUE and H alpha observations continued on a two-year program to monitor the UV variability of three interacting peculiar red giant (PRG) binaries, HD 59643 (C6,s), HD 35155 (S3/2), and HR 1105 (S3.5/2.5). All of these systems were suspected to involve accretion of material from the PRG to a white-dwarf secondary, based mainly on previous IUE investigations. They were primary candidates from earlier surveys of PRG's to test the hypothesis that the Tc-poor PRG's are formed as a result of mass...
Topics: NASA Technical Reports Server (NTRS), IUE, RED GIANT STARS, HYPOTHESES, MASS TRANSFER, SURVEYS,...
A very strong Brackett-gamma hydrogen emission line, and the 2.3 micron CO stellar absorption feature were measured in NGC 253. The presence and strength of the CO feature indicates that late type giant stars produce most of the 2.2 micron continuum emission, while the rate of ionization implied by strength of the Brackett-gamma line indicates that much, perhaps all, of the luminosity detected at far infrared wavelengths originates from a large number of OB stars. As compared to the...
Topics: NASA Technical Reports Server (NTRS), EMISSION SPECTRA, GALAXIES, H GAMMA LINE, CARBON MONOXIDE,...
Detached close binary systems define the main sequence band satisfactorily, but very little is known about the masses of giants and supergiants. High dispersion international ultraviolet explorer satellite observations promise an improvement, since blue companions are now frequently found to late type supergiants. Mu Sagittaril and in particular Xi Aurigae are discussed in more detail. The barium star abundance anomaly appears to be due to mass transfer in interacting systems. The symbiotic...
Topics: NASA Technical Reports Server (NTRS), BINARY STARS, GIANT STARS, IUE, STELLAR EVOLUTION, SUPERGIANT...
The density sensitivity of the emission lines within the UV 0.01 multiplet of C II near 2325 A was examined in additional late type giants and supergiants with deep LWR high dispersion exposures. The new data support the original contention based on these lines that noncoronal red giants possess geometrically extended chromospheres.
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC DENSITY, CHROMOSPHERE, EMISSION SPECTRA, GIANT...
Broad band filter photometry for 57 bright stars of spectral type A2 discussed with peak instrument responses at 3320, 2980, 2460 and 1910 A. The data include nearly all usable filter observations of G, K and M types. Sampling is nearly complete for A and F giants and supergiants, with the exception of Cepheid variables. The basic results presented are relative digital counting rates obtained with a field-stop aperture of 10 minutes of arc. Characteristics of the four filter-photometer...
Topics: NASA Technical Reports Server (NTRS), A STARS, GIANT STARS, HOT STARS, OAO 2, STELLAR...
We investigate, using the modeling code SHAPE, the three-dimensional structure of the bipolar Homunculus nebula surrounding Eta Carinae as mapped by new ESO VLT/X-Shooter observations of the H2 (lambda) = 2.12125 micrometers emission line. Our results reveal for the first time important deviations from the axisymmetric bipolar morphology: 1) circumpolar trenches in each lobe positioned point-symmetrically from the center and 2) offplanar protrusions in the equatorial region from each lobe at...
Topics: NASA Technical Reports Server (NTRS), NEBULAE, MASSIVE STARS, BINARY STARS, BIPOLARITY, STELLAR...
Context. About a quarter of all post-asymptotic giant branch (AGB) stars are hydrogen-deficient. Stellar evolutionary models explain the carbon-dominated H-deficient stars by a (very) late thermal pulse scenario where the hydrogen-rich envelope is mixed with the helium-rich intershell layer. Depending on the particular time at which the final flash occurs, the entire hydrogen envelope may be burned. In contrast, helium-dominated post-AGB stars and their evolution are not yet understood. Aims. A...
Topics: NASA Technical Reports Server (NTRS), HELIUM, DOMINANCE, STELLAR EVOLUTION, ASYMPTOTIC GIANT BRANCH...
The circumstellar envelopes surrounding late-type giants and supergiants were studied using high resolution, photoelectric scans of strong optical resonance lines. A method for extracting the circumstellar from the stellar components of the lines allowed a quantitative determination of the physical conditions in the envelopes and the rates of mass loss at various positions in the red giant region of the HR diagram. The observed strengthening of the circumstellar spectrum with increasing...
Topics: NASA Technical Reports Server (NTRS), GIANT STARS, STELLAR MASS, SUPERGIANT STARS,...
We report the results of an investigation into the physical conditions in the mass outflows of asymptotic giant branch (AGB) carbon stars that are required for the formation of micron-sized presolar graphite grains, either with or without internal crystals of titanium carbide (TiC). In addition to providing detailed information about stellar nucleosynthesis, the structure and composition of presolar grains give unique information about the conditions of grain formation. In the present work we...
Topics: NASA Technical Reports Server (NTRS), ASYMPTOTIC GIANT BRANCH STARS, CARBON STARS, GRAPHITE, GRAIN...
DK UMa (= 24 UMa = HD 82210) is a G4 IV-III star. According to its M(sub v) and B - V color, it is located at the base of the red giant branch, having recently exited from the Hertzsprung Gap. Now poised to start its first ascent along the giant branch, DK UMa is at a significant juncture in its post-main-sequence evolution, offering an important evolutionary comparison for magnetic activity with stars like 31 Comae, which is just entering the Hertzsprung Gap, and older stars like the Hyades...
Topics: NASA Technical Reports Server (NTRS), EMISSION SPECTRA, MAGNETIC VARIATIONS, GIANT STARS,...
We report new observations of the nova RS Ophiuchi (RS Oph) using the Keck Interferometer Nulling Instrument, approximately 3.8 days following the most recent outburst that occurred on 2006 February 12. The Keck Interferometer Nuller (KIN) operates in K-band from 8 to 12.5 pm in a nulling mode, which means that the central broad-band interference fringe is a dark fringe - with an angular width of 25 mas at mid band - rather than the bright fringe used ill a conventional optical interferometer....
Topics: NASA Technical Reports Server (NTRS), BRIGHTNESS DISTRIBUTION, STELLAR ENVELOPES, RED GIANT STARS,...
There is an enormous range in the properties of stars that are losing mass. The red giants responsible for injecting roughly half or more of the material into the interstellar medium are reviewed. The physical properties are described for the out flowing gases. Broadband observation constaints on the dust are described by use of spectrum analysis. Circumstellar dust is identified by carbon-carbon and carbon-hydrogen bonds.
Topics: NASA Technical Reports Server (NTRS), COSMIC DUST, RADIATION PRESSURE, RED GIANT STARS, STELLAR...
Observational evidence for mass loss from cool stars is reviewed. Spectra line profiles are used for the derivation of mass-loss rates with the aid of the equation of continuity. This equation implies steady mass loss with spherical symmetry. Data from binary stars, Mira variables, and red giants in globular clusters are examined. Silicate emission is discussed as a useful indicator of mass loss in the middle infrared spectra. The use of thermal millimeter-wave radiation, Very Large Array (VLA)...
Topics: NASA Technical Reports Server (NTRS), COOL STARS, GIANT STARS, LOSSES, M STARS, MIRA VARIABLES,...
IUE Observations were begun for a two-year program to monitor the UV variability of three interacting peculiar red giant (PRG) binaries, HD 59643 (C6,s) HD 35155 (S3/2), and HR 1105 (S3.5/2.5). All of these systems were suspected to involve accretion of material from the PRG to a white-dwarf secondary, based mainly on previous IUE investigations. From our earlier surveys of PRG's, they were primary candidates to test the hypothesis that Tc-poor PRG's are formed as a result of mass transfer from...
Topics: NASA Technical Reports Server (NTRS), ASYMPTOTIC GIANT BRANCH STARS, BINARY STARS, COMPANION STARS,...
We use data from the Wide-field Infrared Survey Explorer (WISE) all-sky release to explore the incidence of warm dust in the habitable zones around exoplanet-host stars. Dust emission at 12 and/or 22 microns (T(sub dust) approx.300 and/or approx.150 K) traces events in the terrestrial planet zones; its existence implies replenishment by evaporation of comets or collisions of asteroids, possibly stirred by larger planets. Of the 591 planetary systems (728 extrasolar planets) in the Exoplanet...
Topics: NASA Technical Reports Server (NTRS), EXTRASOLAR PLANETS, MAIN SEQUENCE STARS, STELLAR ENVELOPES,...
We propose a model to explain the ultra-bright GeV gamma-ray flares observed from the blazar 3C454.3. The model is based on the concept of a relativistic jet interacting with compact gas condensations produced when a star (a red giant) crosses the jet close to the central black hole. The study includes an analytical treatment of the evolution of the envelope lost by the star within the jet, and calculations of the related high-energy radiation. The model readily explains the day-long that...
Topics: NASA Technical Reports Server (NTRS), RADIO JETS (ASTRONOMY), GAMMA RAY BURSTS, RADIO SPECTRA,...
The dependence of the red edge location on the two fundamental free parameters in the eddy viscosity treatment was extensively studied. It is found that the convective flux is rather insensitive to any reasonable or allowed value of the two free parameters of the treatment. This must be due in part to the fact that the convective flux is determined more by the properties of the hydrogen ionization region than by differences in convective structure. The changes in the effective temperature of...
Topics: NASA Technical Reports Server (NTRS), CONVECTIVE FLOW, EDDY VISCOSITY, GIANT STARS, RED SHIFT,...
The activity in RS Canum Venaticorum (CVn) is investigated. Models for chromospheric structure are developed and the role of magnetic fields both in the photosphere as well as in the chromosphere and upper atmosphere are examined. T Tau stars are also studied from the same points of view. The properties of magnetic field loops are used to help understand the atmospheric structure in RS CVn stars. The concepts developed in the case of these stars appear to be applicable over a much broader...
Topics: NASA Technical Reports Server (NTRS), CHROMOSPHERE, GIANT STARS, PHOTOSPHERE, STELLAR MAGNETIC...
Nine chromospherically active single K giants were identified from surveys of chromospherically active stars. The stars have v sin i's ranging from 6 to 46 km/sec. Such large velocities are not explained by scenarios of main sequence to giant star evolution. Fluxes of the ultraviolet emission lines of these stars are substantially less than those of FK Comae. Many of these giants have a moderate or strong lithium line strongly suggesting that these stars recently evolved from rapidly rotating A...
Topics: NASA Technical Reports Server (NTRS), CHROMOSPHERE, EMISSION SPECTRA, GIANT STARS, IUE, LITHIUM,...
Photoelectric spectral scans at 30-A resolution of 9 dwarfs, 10 giants and 6 supergiants with spectral types GO to M5 were presented. All stars were observed every 4 A from wavelength 3300 to wavelength 7000. Absorption features at this resolution coincide with: strong atomic lines of Fe 1,11, Ca 1,11, Mg 1, and Na 1; vibrational bands of the electronic transitions of TiO, MgH, CaH, SiH, AlH, Cn, Ch, C2, OH, and NH. The dependence of the wavelength 3740 Fe 1 blend and the wavelength 3440...
Topics: NASA Technical Reports Server (NTRS), COOL STARS, SCANNERS, SPECTROPHOTOMETRY, STARS, DWARF STARS,...
The dynamic behavior of the H-rich envelope (0.101 solar mass) of an evolved star (1.1 solar mass) as the luminosity rises to 19000 solar luminosity during the second ascent of the red giant branch. For luminosities in the range 3100 L 19000 solar luminosity the H-rich envelope pulsates like a long-period variable (LPV) with periods of the order of a year. As L reaches 19000 solar luminosity, the entire H-rich envelope is ejected as a shell with speeds of a few 10 km/s. The ejection occurs on a...
Topics: NASA Technical Reports Server (NTRS), STELLAR EVOLUTION, STELLAR MASS EJECTION, GIANT STARS,...
a) Symbiotic Binary System: White dwarf + red giant system. b) Nova: White dwarf builds up mass envelope to the point of thermonuclear fusion. c) Dramatic increase in visual magnitude. d) Recurrent Nova? e) Hints but no strong confirmation of previous nova f) Pre-nova activity: 1) White dwarf shows ongoing variability at level of several in magnitude. 2) V407 Cyg companion is a Mira star showing variability at level of several in magnitude. g) Origin of the gamma rays? 1) Strong shock...
Topics: NASA Technical Reports Server (NTRS), GAMMA RAYS, BINARY STARS, PARTICLE DECAY, RED GIANT STARS,...
Silicon to carbon abundance ratios for population I giants were determined from emission lines originating in the transition layers between stellar chromospheres and coronae. For effective temperatures larger than 6200 K we find a group of stars with increased silicon to carbon but normal nitrogen to carbon abundance ratios. These stars are presumably descendents from Ap stars with increased surface silicon to carbon abundance ratios. For G stars this anomaly disappears as is to be expected due...
Topics: NASA Technical Reports Server (NTRS), A STARS, EMISSION SPECTRA, F STARS, G STARS, GIANT STARS,...
We present an eccentric binary model for the formation of the proto-planetary nebula CRL 2688 (the Egg Nebula) that exhibits multiple concentric shells. Given the apparent regularity of the structure in the Egg Nebula, we postulate that the shells are caused by the periodic passages of a companion star. Such an orbital period would have to lie in the range of 100-500 yr, the apparent time that corresponds to the spacing between the rings. We assume, in this model, that an asymptotic giant...
Topics: NASA Technical Reports Server (NTRS), BINARY STARS, ASYMPTOTIC GIANT BRANCH STARS, STELLAR MODELS,...
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The purpose of the Solar Maximum Repair Mission is to restore the operational capacity of the satellite by replacing the attitude control system module and servicing two of the scientific instruments on board. The mission will demonstrate the satellite servicing capacity of the Space Shuttle for the first time.
Topics: CHROMOSPHERE, RADIATION PRESSURE, STELLAR MASS, INTERSTELLAR MATTER, RED GIANT STARS, STELLAR...
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Possible compounds for the 9.7 micron spectral feature and the 2175A spectral bump are examined. Results from electron microscopy and high resolution transmission electron microscopy are discussed.
Topics: COSMIC DUST, INFRARED SPECTRA, RADIO SPECTRA, RADIATION PRESSURE, RED GIANT STARS, STELLAR...
The formation of hydrocarbons in the oxygen-rich outflows from red giants was studied. The existence of organic molecules in such outflows has been known for several years; however, their surprisingly high abundances has been a mystery since all of the carbon had been thought to be irretrievably locked up in CO, the most strongly bound molecule. CO is the first molecule to form from the atoms present in the star's extended atmosphere, and as strong stellar winds drive a cooling outflow, dust...
Topics: NASA Technical Reports Server (NTRS), STELLAR ENVELOPES, METHANE, HYDROCARBONS, RED GIANT STARS,...
Developments in the understanding and use of chromospheric diagnostics are discussed with emphasis on the following aspects: (1) trends emerging from semiempirical models of single stars; (2) the validity of claims that theoretical models of chromospheres are becoming realistic; (3) the correlation between the widths of Ca 2 H and K line emission cores and stellar absolute luminosity extending over 15 magnitudes (Wilson-Bappu relation); and (4) the existence of systematic flow patterns in...
Topics: NASA Technical Reports Server (NTRS), CHROMOSPHERE, LINE SPECTRA, SPECTRAL LINE WIDTH, STELLAR...
An analytic expression for the integrated H alpha optical depth profile is derived for a one dimensional slab geometry model chromosphere, with electron temperature increasing as a power law with height. The formula predicts H alpha opacity and profile width to be sensitive functions of the thermal gradient. Application of the model to observation reveals that broad H alpha absorption widths in G and K giant stars are consistent with a mean H alpha chromospheric optical depth of 50, while...
Topics: NASA Technical Reports Server (NTRS), CHROMOSPHERE, OPTICAL PROPERTIES, TEMPERATURE GRADIENTS,...
Detailed hydrodynamic modeling of the passage of supernova shocks through the hydrogen envelopes of blue and red progenitor stars was carried out to explore the sensitivity to model conditions of light element production (specifically Li-7 and B-11) which was noted by Dearborn, Schramm, Steigman and Truran (1989) (DSST). It is found that, for stellar models with M is less than or approximately 100 M solar mass, current state of the art supernova shocks do not produce significant light element...
Topics: NASA Technical Reports Server (NTRS), BLUE STARS, BORON ISOTOPES, GALACTIC EVOLUTION, LIGHT...
An eclipsing X-ray binary pulsator consistent with the location of A1540-53 was observed. The source pulse period was 528.93 plus or minus 0.10 seconds. The binary nature is confirmed by a Doppler curve for the pulsation period. The eclipse angle of 30.5 deg plus or minus 3 deg and the 4 h transition to and from eclipse suggest an early type, giant or supergiant, primary star.
Topics: NASA Technical Reports Server (NTRS), ECLIPSING BINARY STARS, PULSARS, X RAY FLUORESCENCE, X RAY...
The Final Report on the formation process of the He I lambda 10830 line in cool giant stars is presented. The research involves observing a sample of cool giant stars with ROSAT. These stars were selected from the list of bright stars which display He I lambda 10830 in absorption or emission and lie on the cool side of the coronal dividing line. With measured x ray fluxes or upper limits measured by the Position Sensitive Proportional Counter (PSPC), the role x rays play in the formation of...
Topics: NASA Technical Reports Server (NTRS), COOL STARS, GIANT STARS, HELIUM ISOTOPES, LINE SPECTRA,...
Drawing a coherent picture of the observational characteristics of the Diffuse Interstellar Bands (DIB's) and the physical and chemical properties of its proposed carriers was the focus of this NASA sponsored conference. Information relating to absoption spectra, diffuse radiation carriers, carbon compounds, stellar composition, and interstellar extinction involving T-Tauri stars, Reflection Nebulae, Red Giants, and accretion discs are discussed from those papers presented at the conference,...
Topics: NASA Technical Reports Server (NTRS), ABSORPTION SPECTRA, ASTRONOMY, CARBON COMPOUNDS, CHEMICAL...
