Showing papers in "Astrophysical Journal Supplement Series in 1983"

A survey of galaxy redshifts. IV - The data

Abstract: We present here the complete list of the best available radial velocities for the 2401 galaxies in the merged Zwicky-Nilson catalog brighter than 14.5 m/sub Z/ and with b/sup Pi/ above +40/sup 0/ or below -30/sup 0/. Almost 60% of the redshifts are from the CfA survey and are accurate to typically 35 km s/sup -1/.

Dynamically consistent nonlinear dynamos driven by convection in a rotating spherical shell. II: Dynamos with cycles and strong feedbacks

Abstract: Calculs additionnels du modele de dynamo decrit par Gilman et Miller. On applique les resultats au probleme de dynamo solaire. La principale difference hydrodynamique avec Gilman et Miller est que la viscosite et la diffusivite thermique sont reduites d'un facteur 10

Groups of galaxies. III. the CfA survey

Abstract: We present a statistically homogeneous group catalog (CfA) based on the CfA redshift survey (Huchra et al.). Groups in the catalog are all density enhancements in redshift space of a factor greater than 20. Group members are identified according to the procedure described in our previous study (Huchra and Geller) of a shallower whole-sky sample. All groups contain at least three members. Of the 176 groups in the CfA catalog, 102 have been identified in one or more previous studies. Because our algorithm searches for volume rather than surface density enhancements, the groups in a given region generally change only through the addition of fainter members when the magnitude limit of the galaxy catalog increases. In the region of overlap, agreement between our shallow catalog and the CfA catalog is excellent.

The quadrupole oscillations of neutron stars

Abstract: Etude de l'influence de l'equation d'etat de la matiere (dans un regime a densite nucleaire) sur le comportement dynamique des etoiles a neutrons

X-ray line emission from supernova remnants. I - Models for adiabatic remnants

Abstract: “NASA’s Beyond Einstein Program: An Architecture for Implementation,” Kennel, C., Rothenberg, J., Adelberger, E., Adkins, W., Applequist, T., Barrowman, J., Bearden, D., Devlin, M., Fuller, J., Gebhardt, K., Gibson, W., Harrison, F., Lankford, A., McCarthy, D., Meyer, S., Primack, J., Randall, L., Sarazin, C., Ulvestad, J., Will, C., Witherell, M., & Wright, N., (Washington: National Academy of Sciences), i–xi,1–174 (2007), ISBN: 978-0-309-11162-1

Chemical compositions of planetary nebulae.

Abstract: The chemical compositions of 41 planetary nebulae are established on the basis of an analysis of image tube scanner measurements, supplemented by IUE data. An attempt is made to calculate a theoretical model that gives satisfactory values of the observed intensities, as well as a number of excitation-sensitive ratios, in order to obtain ionization correction factors applicable to the ionic concentrations that will lead to total abundance values. The quality of individual nebular analyses varies, depending on the completeness and accuracy of the observational data and the complexity of the nebular structure. Quality estimates are assigned for each element in each nebula, and an overall reliability index is given to each object. It is concluded that the confidence with which one can speak of the chemical composition of a nebula varies significantly.

Proton-nucleus total inelastic cross sections - An empirical formula for E greater than 10 MeV

Abstract: An empirical formula for the total inelastic cross section of protons on nuclei with charge greater than 1 is presented. The formula is valid with a varying degree of accuracy down to proton energies of 10 MeV. At high energies (equal to or greater than 2 GeV) the formula reproduces experimental data to within reported errors (about 2%).

Rotational studies of late-type stars. II: Ages of solar-type stars and the rotational history of the Sun

Abstract: In the first part of this investigation, age indicators for solar-type stars are discussed. A Li abundance-age calibration is derived; it indicates that 1 M/sub sun/ stars have lost as much as 80% of their initial Li before reaching the main sequence. The e-folding time for Li depletion on the main sequence is 1 1/4 Gyr. The distribution of Li abundances for 1 M/sub sun/ stars is consistent with a uniform initial Li abundance for all stars.

The magnetic fields of the helium-weak B stars

Abstract: Etude des champs magnetiques dans 30 etoiles B faibles en helium, une etoile B de la branche horizontale et une etoile sd OB

Star clusters and stellar evolution. I. Improved synthetic color-magnitude diagrams for the oldest clusters.

Abstract: New stellar evolutionary sequences extending from the main sequence to the base of the red giant branch have been computed assuming two values of the helium abundance, Y = 0.2, for each of the adopted heavy-element abundances Z = 0.0001, 0.001, 0.003, 0.006, 0.01, and 0.0169 (solar). Main-sequence masses, in the range of 0.6 to 1.3 M/sub sun/, were chosen in order to produce turnoff luminosities similar to those observed for the galactic globular and old disk clusters. The major improvements over previous studies of this kind include: (1) the use of available model atmosphere grids to provide more realistic surface boundary conditions, (2) the adoption of the latest Los Alamos opacities supplemented by new low-temperature opacity data which included the contributions from the most important molecules, and (3) the determination of the effects of changing the value of the mixing-length parameter, ..cap alpha.., on the positions of stars on the H-R diagram so as to enable one to match both the observed main-sequence and giant-branch positions simultaneously.

Spectroscopy of cataclysmic variables. I. Observations.

Abstract: Spectroscopic observations of 69 cataclysmic variables are presented. Representative spectra, accurate coordinates, and finding charts are given for each object. Line strengths, equivalent widths, and line widths for all emission lines in 153 spectra are tabulated. The spectra are discussed briefly, and notes to selected objects are given.

A survey of ultraviolet interstellar absorption lines

Abstract: A telescope-spectrometer on the Copernicus spacecraft made possible the measurement of many ultraviolet absorption lines produced by the interstellar gas. The present survey provides data on ultraviolet absorption lines in the spectra of 88 early-type stars. The stars observed are divided into four classes, including reddened stars, unreddened bright stars, moderately reddened bright stars, and unreddened and moderately reddened faint stars. Data are presented for equivalent width, W, radial velocity V, and rms line width, D, taking into account some 10 to 20 lines of N I, O I, Si II, P II, S II, Cl I, Cl II, Mn II, Fe II, Ni II, Cu II, and H2. The data are based on multiple scans for each line. Attention is given to details of observations, the data reduction procedure, and the computation of equivalent width, mean velocity, and velocity dispersion.

Supernova remnants in the Magellanic clouds.

Abstract: The present updated catalog of SNRs in the Large and Small Magellanic Clouds (LMC and SMC) incorporates remnants recently discovered as a result of coordinated X-ray, optical, and radio surveys, and contains 25 confirmed SNRs in the LMC and six in the SMC. Optical images are included for all of the new SNRs, together with X-ray isophotes for 24 of the SNRs in the LMC which have been obtained with the high resolution imager and imaging proportional counter of the Einstein Observatory. The cumulative number-diameter relation for Type II SNRs with D smaller than 50 pc in the LMC is N(D)= 0.36 D exp 1.0 + or 0.2, suggesting that the SNRs have evolved much faster than expected from Sedov theory and that the free expansion phase dominates their evolution up to diameters of 30-40 pc. SNR production frequencies in the LMC and SMC are calculated to be 1/275 and 1/800 years, respectively, or nearly equal to the galaxies' luminosity ratios.

Line radiation from a hot, optically thin plasma: collision strengths and emissivities

Abstract: We collect theoretical and experimental data for collision strengths of the strongest multiplets between 1 and 3000 A in a hot, optically thin plasma. The elements included are H, He, C, N, O, Ne, Mg, Si, S, and Fe. Simple power-law fits, as a function of gas-kinetic electron temperature, are provided for the collision strengths of the strongest multpletes for temperatures between 4 x 10/sup 4/ and K. The fits are good to approx.10% for temperatures within a factor of 3 of the temperature at which the steady-state equilibrium ion abundance peaks. The collision strengths for these strong multiplets are also used to calculate the multiplet emissivities for a plasma assumed to be in steady-state collisional ionizaton equilibrium. The multiplet emissivities are given for temperatures between 2.5 x 10/sup 6/ and 1 x 10/sup 8/ K. We also present the total steady-state emissivity (including continuum) and the emissivities in selected energy bins. Note, however, that steady-state collisional ionization equilibrium is not a good assumption for shock-heated plasmas for temperatures lower than approx.3 x 10/sup 6/ K.

JPL pulsar timing observations. II - Geocentric arrival times

Abstract: Monitoring of the behavior of naturally pulsating galactic radio sources, or pulsars, through regularly spaced measurements of pulse arrival times, has been conducted by several laboratories. A tabular presentation is here made of pulse arrival time measurements from the NASA Deep Space Network between late 1968 and early 1981. By expressing the measurements in ephemeris time, and referring them to the geocenter, usable tables of results have been generated for each pulsar listed in the first of the tables given. The considerations addressed by the tables are: (1) a necessary step in the study of pulsar dynamics is the reduction of topocentric arrival times to the barycenter of the solar system; (2) the tabulated data are accessible to all opinions as to the procedures to be used in interpreting arrival time data; and (3) different observing programs can usually be combined to produce an improvement in the total data set.

Radial velocities of planetary nebulae.

Abstract: On presente un catalogue de toutes les vitesses radiales connues et de leurs incertitudes pour 524 nebuleuses planetaires. Cent deux sources ont ete consultees, comprenant 920 mesures de vitesse distinctes. On discute des diverses sources d'erreurs dans les mesures et on explique les techniques utilisees pour leur evaluation. On presente quelques considerations statistiques sur les vitesses radiales de la population des nebuleuses planetaires

Infrared photometry, bolometric luminosities and effective temperatures for giant stars in 26 globular clusters.

Abstract: Observations IR de 307 etoiles geantes dans 26 amas globulaires. On examine l'influence de l'absorption H 2 O sur les couleurs IR. On donne les correlations couleur-couleur et les diagrammes couleur-magnitude qui permettent d'isoler certains amas a rougissements problematiques ou pour lesquels les donnees optiques sont de faible qualite

Galactic ring nebulae associated with Wolf-Rayet stars. VIII: Summary and atlas

Abstract: On donne les photographies de 10 nebuleuses annulaires galactiques associees a des etoiles Wolf-Rayet et les references des photographies publiees pour les autres nebuleuses. Il y a 7 nebuleuses annulaires du type W (vent stellaire-bulle ejectee), 2 du type E (ejection stellaire), 4 du type Rs (region HII en forme d'enveloppe) et 2 du type R a (region HII amorphe)

A survey of HI absorption at low latitudes

Abstract: Mesures VLA du spectre d'absorption a 21 cm en direction de 88 sources compactes avec IBI<15°. On presente les spectres d'absorption avec une resolution en vitesse de 1,55 kms −1 et une bande utile superieure ou egale a 260 kms −1 . On donne les spectres d'emission correspondants obtenus avec le telescope de 91 m de Green Bank

An infrared search for very low mass stars : JHK photometry and results for composite systems.

Abstract: Photometrie JHK d'environ 100 naines blanches et 60 naines rouges. Certaines etoiles sont des binaires naines rouge et blanche, des systemes qui peuvent contenir un disque d'accretion ou une primaire sous naines, et des etoiles sans exces de flux IR. On considere la detection astrometrique de certains systemes et on tabule de nouveaux mouvements propres de compagnons possibles

The chemical composition of stars in globular clusters.

Abstract: We present detailed analyses for stars in seven globular clusters, bringing the total number of globular clusters analyzed using high resolution spectroscopy and model atmospheres to 23. Equivalent-width data published by other investigators for some clusters have been reanalyzed to derive abundances on a uniform scale with our own. Values of (Fe/H) range from -2.2 (NGC 6397) to -0.9 (NGC 362). Abundances ratios of various elements relative to iron are significantly different from their solar ratios, and it is clearly incorrect to characterize a cluster by a single heavy-element parameter. The ..cap alpha.. elments, represented largely by calcium and titanium, are substantially enhanced in most clusters, with values of (..cap alpha../H) ranging from -0.45 (NGC 362) to -1.8 (NGC 6397).

A near-infrared and optical study of X-Ray selected Seyfert Galaxies.I. Observations.

Abstract: Observations photometriques en bandes larges entre 0,35 et 3,5 μm d'un echantillon complet de galaxies RX pre-Einstein, la plupart de nature Seyfert Pour la plupart des objets, le flux croit rapidement lorsqu'on passe de l'optique a l'IR Quelques sources eloignees, tres lumineuses ont toutefois des continua relativement plats Les observations montrent que la contribution stellaire a la lumiere du noyau des galaxies de Seyfert de luminosite faible ou moyenne est souvent significative

Strong radio sources in bright spiral galaxies. III: Disk emission

Abstract: On a selectionne deux echantillons complets de galaxies spirales brillantes pour leur emission radio intense a 1415 MHz. Le premier contient 30 galaxies dont les diametres principaux optiques depassent D 0 =2,5' et qui ont des temperatures de brillance du disque vu de face T d ≥2,5 K. Le second contient 39 galaxies plus brillantes que B T 0 =12 avec des rapports de luminosite radio-a-optique R≥40. Les galaxies ont ete cartographiees a 1465 MHz, la plupart avec une resolution 15″-20″, et sept avec une resolution de 6″. Au moins 80% de leur flux a 1415 MHz est non-thermique. La brillance maximale pour la surface, vue de face de ces disques radio est ≃40 K a 1465 MHz

The star-forming history of the young cluster NGC 2264.

Abstract: UBVRI H-alpha photographic photometry was obtained for a sample of low-mass stars in the young open cluster NGC 2264 in order to investigate the star-forming history of this region. A theoretical H-R diagram was constructed for the sample of probable cluster members. Isochrones and evolutionary tracks were adopted from Cohen and Kuhi (1979). Evidence for a significant age spread in the cluster was found amounting to over ten million yr. In addition, the derived star formation rate as a function of stellar mass suggests that the principal star-forming mass range in NGC 2264 has proceeded sequentially in time from the lowest to the highest masses. The low-mass cluster stars were the first cluster members to form in significant numbers, although their present birth rate is much lower now than it was about ten million yr ago. The star-formation rate has risen to a peak at successively higher masses and then declined.

Luminosity distribution in galaxies. II. A study of accidental and systematic errors with application to NGC 3379.

Abstract: On etudie successivement les erreurs provenant de la photometrie photographique, de l'etalonnage photoelectrique, des effets instrumentaux et atmospheriques et de l'interference galactique et extragalactique

Electron excitation rates among fine structure levels in O III

Abstract: Electron collision strengths have been calculated for 146 transitions among the fine-structure levels in O III using a suitable transformation of LS coupling reactance matrix elements computed with the R-matrix method. These have been obtained at a fine energy grid in an energy region below 5.16 Ry and are found to be varying with electron energy, exhibiting a complicated resonance structure in almost the entire energy range. These have been averaged over a Maxwellian distribution of electron energies to get the effective collision strengths which are very simply related to the excitation and the de-excitation rate coefficients. The results are tabulated in a temperature region below 60,000 K. These are the first extensive results in the literature and are believed to be highly useful for astrophysical plasma diagnostics.