Computed and observed cyanide-radical spectra of three N stars in the infrared
N stars Y CVn, RY Dra and 19 Psc IR synthetic cyanide radical spectrum analysis, determining C 12/C 13 ratio
Fay, T. D., Jr.↗
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Scanner observations of cool stars from 3400 to 11,000 A.
Evaluation of photoelectric scans of the M supergiant alpha Ori and the carbon stars 19 Psc, W Ori, and DS Peg made at 20-A resolution from 3400 to 6000 A and at 40-A resolution from 6000 to 11,000 A. The data are corrected for atmospheric extinction and for the instrumental response to obtain plots of log flux per unit frequency interval versus wavelength. The dominant spectral features are due to C2, CN, and TiO; the variation of these features with spectral class is pointed out.
Fay, T.↗
An inverter/controller subsystem optimized for photovoltaic applications
Conversion of solar array dc power to ac power stimulated the specification, design, and simulation testing of an inverter/controller subsystem tailored to the photovoltaic power source characteristics. Optimization of the inverter/controller design is discussed as part of an overall photovoltaic power system designed for maximum energy extraction from the solar array. The special design requirements for the inverter/ controller include: a power system controller (PSC) to control continuously the solar array operating point at the maximum power level based on variable solar insolation and cell temperatures; and an inverter designed for high efficiency at rated load and low losses at light loadings to conserve energy.
Pickrell, R. L.↗
C3 and infrared spectrophotometry of Y Canum Venaticorum
The 1.2- to 5.6-micron spectrum of the carbon star Y CVn is presented and discussed. The observations were made from the Kuiper Airborne Observatory at an altitude of 12.5 km, thereby avoiding most of the absorption due to terrestrial water vapor. Comparison of Y CVn near 5 microns with laboratory spectra provides possible evidence for the presence of the linear triatomic molecule C3. For the first time in a carbon star the clearly formed band heads of the CN red system between 1.2 and 2.3 microns are observed. Corroborative evidence for the presence of the molecules HCN and C2H2 is presented, and the relative contributions of C3, HCN, and C2H2 to the 3.1-micron absorption band are discussed. Spectra of two other carbon stars, TX Psc and S Cep, are presented for comparison.
Goebel, J. H.↗
Starspots as the cause of the intrinsic light variations in RS Canum Venaticorum type stars
A starspot model is proposed to interpret the light curves of three RS CVn type binary systems. Two of the systems are RS CVn and SZ Psc, which are detached, while the third system, RT Lac, is semidetached. Solar activity and the surface activity of the RS CVn type stars are compared. It is found that the spot model permits the detailed fitting of both the out-of-eclipse complications and the distorted shapes of the secondary eclipses in the light curves of these stars.
Eaton, J. A.↗
Detection of X-ray emission from the vicinity of two short-period RS CVn-like binaries
Two new soft X-ray sources H0118 + 067 and H0630 + 82 have been detected with a low energy detector of the HEAO A-2 experiment. Short-period RS CVn-like binaries UVPsc and SV Cam lie within the error boxes of these sources and are proposed as the optical identifications for the two X-ray sources. The light curve of H0118 + 067, identified with UV Psc, indicates an X-ray flare event which commenced on 1978 January 11.6 and persisted until at least January 12.7. It is suggested that H0118 + 067 and the flaring X-ray source H0123 + 075, detected by the medium and high energy detectors of the HEAO A-2 experiment, may be the same object. The observed X-ray luminosity of the sources are in the same range as observed for other RS CVn binaries. The X-ray emission is probably of coronal origin.
Agrawal, P. C.↗
Reproducibility of polycarbonate reference material in toxicity evaluation
A specific lot of bisphenol A polycarbonate has been used for almost four years as the reference material for the NASA-USF-PSC toxicity screening test method. The reproducibility of the test results over this period of time indicate that certain plastics may be more suitable reference materials than the more traditional cellulosic materials.
Hilado, C. J.↗
Aerosol measurements from earth orbiting spacecraft
The global aerosol data base evolving from monitoring being done by Stratospheric Aerosol Measurement (SAM) II and Stratospheric Aerosol and Gas Experiment (SAGE) since the fall of 1978 is presented. Data reveal that polar stratospheric clouds (PSC) enhance extinction and optical depths by up to two orders of magnitude and an order of magnitude, respectively. These data are over background 1000 nm values of approximately 1.2 x 10 to the -4th per km, and 1.3 x 10 to the -3rd, respectively. SAGE has offered, for the first time, quantitative measurements of volcanic eruptions on a nearly global basis, and estimates are given for the amount of aerosol injected into the stratosphere from each volcano. For example, Northern Hemisphere aerosol was enhanced by more than 100% by the 1980 eruption of Mount St. Helens, which produced about 0.32 x 10 to the 6th metric tons of aerosol. A cirrus cloud data base is being developed which will be useful in earth radiation and water vapor budget studies. Cross-section, contour, and temperature variation diagrams are included.
Mccormick, M. P.↗
The ultraviolet spectra of three N-type carbon stars
The paper reports the successful detection of the ultraviolet spectra of three N-type carbon stars: BL Ori, TX Psc, and T Ind. Exposures of approximately 2-3 hours with the LWR camera of the IUE Satellite at low dispersion were necessary to record the ultraviolet flux. The shortward extension of the photospheric continuum is well exposed down to about 2800 A, with strong molecular and atomic absorption features. The spectrum appears not to be seriously affected by the unknown opacity source which blankets N stars (especially redder ones) in the violet. Emission lines of Mg II (h and k) and C II (2325 A) are conspicuous, indicating the presence of chromospheres in the stars. The ratios of integrated fluxes in the Mg II lines and C II lines to bolometric flux are respectively much smaller and slightly smaller than values observed in oxygen-rich M giants and supergiants.
Johnson, H. R.↗
Results from the occultation of 14 Piscium by (51) Nemausa
Observations of the September 11, 1983 occultation of 14 Psc by the asteroid (51) Nemausa were obtained at six sites distributed across the northern two-thirds of the track. The observations are well represented by an elliptical limb profile with a semimajor axis of 84.9 + or - 2.0 km and oblateness (1-b'/a') 0.20 + or - 0.05. The mean radius of 74 + or - 4 km agrees with the 1979 occultation effective radius of 76.5 + or - 4 km and the published radiometric radius of 75.5 km (Morrison and Zellner, 1979).
Dunham, E. W.↗
Dual polarization VLBI observations of stellar binary systems at 5 GHz
The binary systems Sigma CrB, SZ Psc, HR 1099, UX Ari, HR 5110, Algol, and Cyg X-1 are characterized in terms of marcsec-scale radio structure on the basis of dual-polarization observations at 4.969-4.997 GHz, obtained with an international VLBI array comprising the 100-m Effelsberg, 36-m Haystack, 42-m Green Bank, 26-m Fort Davis, 130-m-equivalent VLA, and 40-m Owens Valley telescopes (system temperatures 40-70 K) at 22-14 h UT on July 26-27, 1983. The data are presented in graphs and tables and discussed in detail. Single Gaussian brightness distributions with theta(FWHM) = 0.5-2.0 marcsec and brightness temperatures (2-200) x 10 to the 8th K are determined for four sources; core-halo structures are found for UX Ari and Algol; and an upper limit of 50 microarcsec is established for the angular separation of the regions of left and right circular polarization. The gross features seen in RS CVn systems are explained in terms of a simple expanding-coronal-loop model of flare events.
Mutel, R. L.↗
SAM 2 measurements of the polar stratospheric aerosol, volume 2
The Stratospheric Aerosol Measurement (SAM) 2 sensor aboard Nimbus 7 is providing extinction measurements of Antarctic and Arctic stratospheric aerosols with a vertical resolution of 1 km. Representative examples and weekly averages including corresponding temperature profiles provided by NOAA for the time and place of each SAM 2 measurement (Oct. 1981 - Apr. 1982) are presented. Contours of aerosol extinction as a function of altitude and longitude or time are plotted, and aerosol optical depths are calculated for each week. Typical values of aerosol extinction at 1.0 micron in the main lower stratospheric aerosol layer for this time period are 2 to 4 times 10 to the -4 power/km. for the Antarctic region and 0.5 to 1 times 10 to the -3 power/km. for the Arctic region. Stratospheric optical depths are about 0.001 to 0.004 for the Antarctic region and 0.003 to 0.004 at the beginning to about 0.006 at the end of the time period for the Arctic region. Polar stratospheric clouds (PSC's) were observed during the Arctic winter, as expected. This report provides, in a ready-to-use format, a representative sample of the seventh semester of data to be used in atmospheric and climatic studies.
Mccormick, M. P.↗
A search for rotational modulation of the ultraviolet spectra of Psi 3 Piscium and 31 Comae Berenices
IUE observations were made daily over a seven-day interval to search for rotational variability in the ultraviolet emission lines of two rapidly rotating, early G giants, Psi 3 Psc and 31 Com. No evidence was found to suggest that the chromospheric and transition-region lines of these stars, or their ultraviolet continua near 1725 A, are modulated by rotation. The uniformity of the ultraviolet emission of these giants can be accounted for if their outer atmospheres are heated by acoustic waves. If the heating is a manifestation of dynamo-generated magnetic fields as on the sun, then regions of magnetic activity must be rather evenly distributed in longitude over the stellar surface.
Simon, T.↗
The outer atmosphere of the carbon star TX Piscium
A high-resolution LWP IUE spectrum of the bright N-type carbon star TX Psc demonstrates that the Mg II h and k emission profiles are strongly affected by absorption from Mg II, Mn I, probably Fe I, and possibly from molecules. The indication that the absorbing matter has a column density of not less than 10 to the 20th H atoms or molecules per sq cm is consistent with absorption in a slowly expanding envelope. The integrated Mg II line flux is found to be much greater than in 1981, and the radio CO (J = 1 - 0) line from the circumstellar shell is detected. Results for a column density of not larger than 10 to the 22nd H2 molecules/sq cm, and a radial velocity close to that of the star, are in agreement with those obtained from UV data. Some dust emission from carbon grains is suggested by the far infrared flux distribution, and a mass-loss rate estimation for the star of 10 to the -6th to 10 to the -8th solar masses is obtained.
Eriksson, K.↗
Mass return to the interstellar medium from highly-evolved carbon stars
Data produced by the Infrared Astronomy Satellite (IRAS) was surveyed at the mid- and far-infrared wavelengths. Visually-identified carbon stars in the 12/25/60 micron color-color diagram were plotted, along with the location of a number of mass-losing stars that lie near the location of the carbon stars, but are not carbon rich. The final sample consisted of 619 objects, which were estimated to be contaminated by 7 % noncarbon-rich objects. The mass return rate was estimated for all evolved circumstellar envelopes. The IRAS Point Source Catalog (PSC) was also searched for the entire class of stars with excess emission. Mass-loss rates, lifetimes, and birthrates for evolved stars were also estimated.
Latter, W. B.↗
Ultraviolet spectra of the N-type carbon star TX Piscium
Nine IUE low resolution spectra of TX Psc, one of the brightest N-type carbon stars, were analyzed. The integrated flux of the Mg II (UV 1) line (blend of h and k) varies by a factor of 7, and the flux of other lines varies similarly and in phase. No variations greater than a factor of 2 occur in the continuous flux. Synthetic spectra from a model chromosphere show surprisingly good agreement with the IUE observations. The enormous influence of the wings of the Mg I resonance line is noted, suggesting it may be a major part of the well-known violet and ultraviolet opacity in cool carbon stars.
Johnson, Hollis R.↗
Variability of ultraviolet emission in the carbon star TX Piscium
Multiple low-resolution IUE observations of the cool carbon star TX Psc (N0; C6, 2) permit an analysis of the variations in strength of the strongest emission lines - the Mg II line at 2800 A, the C II line at 2330 A, and certain Fe II lines. The integrated flux of the Mg II line varied by at least a factor of eight, while that of the C II line varies by at least a factor of five. The variations in Fe II may be considerably larger. The lines appear to vary together. The continuous flux in the best observed range from 2800 to 3200 A does not vary noticeably.
Johnson, Hollis R.↗
Ultraviolet spectra and chromospheres of cool carbon stars
The authors assemble and discuss all available low-resolution IUE spectra of N-type carbon stars - including TW Hor, BL Ori, UU Aur, NP Pup, U Hya, T Ind, and TX Psc. Identification of spectral features is aided by a composite spectrum. Shortward of 2850 A only emission lines of C II, Mg II, Al II, and Fe II are seen, while the spectrum longward of 2850 A appears to be a photospheric absorption spectrum with a few superposed emission lines of Fe II. The most prominent absorption features are due to Fe I, CH, and CaCl. The emission feature at 2325 A, second only to Mg II in strength, is conclusively identified as C II (UV 0.01). Ultraviolet spectra of N-type carbon stars are similar to, though the emission-line fluxes are generally weaker than, those of the coolest M-giant stars available, such as HD 18191 (M6 III).
Johnson, Hollis R.↗