• Photoelectric Photometry of Some Galaxies in the Region of the Virgo Cluster

      Tifft, W. G.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1973-01)
      Four color photometry of 26 galaxies, mostly in the region of the Virgo Cluster, is presented.
    • Photometric Standards for the Southern Hemisphere

      Bok, B. J.; Bok, P. F.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1969-08)
    • Polarization and Structure of the Crab Nebula : Proceedings of the 23rd IAU Colloquium

      Felten, J. E.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1973-04-03)
      Present knowledge of the optical, radio and X -ray polarization of the Crab is reviewed and discussed as it bears on the structure of the magnetic field, time scales in the nebula, and relations between nebula and pulsar. Not as much high -resolution polarimetry has been done on the Crab as might have been expected. Loops of field and a large -scale structure can be recognized, but it is not known whether the fields generally are smooth or chaotic on a small scale. Field lines tend to curl around the filaments. The large angular size of the X -ray source poses a difficulty to conventional theory. The form of the nebula does not single out the pulsar as its source, and the exact relation between pulsar and nebula is uncertain. The wave -field or "synchro- Compton" interpretation of the continuum emission is erroneous but has led to interesting observations of circular polarization. Circular polarization of the ordinary synchrotron radiation might be observable in the radio band. Magnetic flux may have been generated in the nebula by winding of lines around the rotating pulsar. Polaroid photographs then suggest that the pulsar rotation axis is roughly NW -SE, but confirmation is lacking.
    • Polarization of Radio Sources. I. Transfer of synchrotron Radition through an Extended Radio Source with Faraday Rotation|Polarization of Radio Sources. I. Homogeneous Source of Arbitrary Optical Thickness

      Pacholczyk, A. G.; Swihart, T. L.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1966-11)
      The problem of transfer of radiation in a medium with polarized emission, polarized absorption and Faraday rotation of the plane of polarization is formulated. Solutions are obtained for the case of a homogeneous source. In the range of frequencies for which a medium is optically thick the degree of polarization of synchrotron radiation depends on the type of absorption process and is different for synchrotron absorption and for thermal absorption. It is therefore suggested that the low frequency polarization measurements of radio sources with curved spectra may determine whether synchrotron self -absorption or thermal absorption or another process is responsible for the low frequency curvature in spectra of certain radio sources.
    • Polarization of Radio Sources. II. Faraday Effect in the Case of Quasitransverse Propagation

      Pacholczyk, A. G.; Swihart, T. L.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1970)
      Under the conditions of quasitransverse propagation of electromagnetic waves in a magnetoionic plasma, the effect analogous to Faraday rotation in the quasilongítudinal case (which we will call Faraday pulsation) can produce a large elliptical polarization of originally linearly polarized radiation. Therefore, the presence of elliptical polarization in the radiation cannot serve as a means for distinguishing between a synchrotron mechanism with high energy electrons and any other type of emission process in radio sources in which conditions suggesting quasi - transverse propagation (large magnetic fields) may take place. The Faraday pulsation has a wavelength dependence through which it can be identified.
    • A Possible Rotation Chain of Galaxies|Possible Systematic Redshifts in a Chain of Galaxies

      Gregory, S. A.; Connolly, L. P.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1972-11)
      Redshifts are reported for two groups of galaxies. Although these two groups have previously been assigned to the same cluster, their redshifts indicate that they are not associated. A systematic variation of redshifts is found across the chain of one of these groups, Abell 2247, and three possible interpretations are discussed. It is concluded that rotation of the chain is the most likely explanation of the systematic motions.
    • Possible Thermal Histories of Intergalactic Gas

      Weymann, R. J. (Steward Observatory, The University of Arizona (Tucson, Arizona), 1967-07)
    • Pulsation Constants and Densities for Double Mode Variables in the Cepheid Instability Strip

      Fitch, W. S.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1970)
      Pulsation constants and period ratios are given for the first six radial pulsation modes of a set of seven polytropes with indices ranging from n = 2.25 to n = 4.00. The polytrope results are combined with published theoretical data from stellar model pulsation calculations and observational data on thirteen double mode variables in the Cepheid instability strip to obtain four interpolation formulae relating fundamental periods Po, pulsation constants Qo, and period ratios P1 /P0 and P2 /P1. The derived relations are used to obtain accurate densities for the thirteen observed variables, which include six dwarf Cepheids or AI Vel stars, one S Sct star, one RR Lyr star, and five Cepheids. Approximate masses and luminosities are obtained for some of these stars. The probable connection between mass- luminosity ratios and the existence of double mode variables is discussed.
    • Radiative Acceleration of Material

      Weymann, R. J.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1973)
    • Rapid Evolution of Galactic Nuclei : Proceedings of the 44th IAU Symposium

      Tifft, W. G.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1970-08)
    • Redshift Magnitude Bands and Quasi Stellar Absorption Line Multiple Redshifts

      Tifft, W. G.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1972)
      Quasi stellar absorption line redshifts are shown to be consistent with the redshift- magnitude band pattern concept. The redshifts in multiple redshift objects tend to concentrate at band crossings corresponding to the magnitude of each object.
    • Redshift Quantization in the Lyman-alpha Forest and the Measurement of qo

      Cocke, W. J.; Tifft, W. G.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1988-12)
      We present evidence for redshift quantization in the Lyman -a forest of several QSOs. The Ly -a data are at redshifts z from 1.89 to 3.74, and the theory of redshift quantization proposed by Cocke (1983, 1085) is used to scale the quantization interval (24.15 km s -') to these high redshift. The sealing depends on the deceleration parameter qo, and the quantization is present at a statistical significance of greater than 99% for qo = 1/2. This may be taken as confirming the inflationary model of the early history of the universe. The significance of the quantization is highest at go rs 0.48, and the width of the peak is about 0.03 . The result can also be seen as providing confirmatory evidence for both the theory of the redshift quantization and the above value of qo, but at a significance of only 03 %. The scenario proposed for the relativistic generalization of the theory is that of fermion wavefunctione and quantum operators in a background Riemannian spacetime satisfying Einstein's field equations.
    • Redshift-Magnitude Bands, Quasi Stellar Sources, and Systems of Redshift

      Tifft, W. G.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1972-08)
      The visibility and character of redshift- magnitude bands in a diagram of general field galaxies compared to specific clusters depends upon the cosmological model. In the normal expanding universe model where galaxies have lives comparable to the age of the universe, no band structure should be visible outside of clusters. Band structure is, however, shown to exist among quasi stellar sources and to show the identical slope and band spacing characteristics as do the galaxies in the Coma cluster. At least 14 bands can be identified forming a convergent band series among QSS emission line objects. The validity of the band phenomenon is tested by power spectrum analysis and shown to be highly significant. The distribution of points about the band structure is Gaussian. Cross projections of the band system are shown to give rise to harmonic periodicities which can explain some or all of the periodicities observed in the z distribution of QSS objects. The Coma galaxy band system is shown to be a scaled version of the QSS band system. Galaxies appear to occupy a separate band system which is convergent to the start of the QSS system as its series limit. QSS absorption line objects are further shown to apparently form a third independent band system beginning at the high redshift limit of the QSS emission line system. The band phenomenon is briefly discussed in terms of a model invoking multiple states of matter, rapid galaxy evolution, and possible time evolution of matter observed as a function of lookback time in a singular origin Universe.
    • Search for Close Binary Evolved Stars

      Saffer, R. A.; Liebert, J.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1988-10)
      We report on a search for short -period binary systems composed of pairs of evolved stars. The search is being carried out concurrently with a program to characterize the kinematical properties of two different samples of stars. Each sample has produced one close binary candidate for which further spectroscopic observations are planned. We also recapitulate the discovery of a close detached binary system composed of two cool DA white dwarfs, and we discuss the null results of Ha observations of the suspected white dwarf /brown dwarf system G 29-38.
    • Solid Hydrogen Coated Graphite Particles in the Interstellar Medium, I

      Wickramasinghe, N. C.; Krishna Swamy, K. S.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1968-11)
      Solid hydrogen coated graphite particles may be expelled from regions of star -formation into the general interstellar medium. The solid para- hydrogen mantles, which contain a small proportion of orthomolecules are stable against evaporation in the general interstellar radiation field. They are also stable against physical and chemical sputtering in HI regions. Extinction efficiencies are calculated for solid hydrogen particles and for graphite particles with solid hydrogen mantles. Graphite core -solid hydrogen grains are capable of producing excellent agreement with the interstellar extinction observations from 2u - 1100 A. The graphite core radius may be in the range ro = 0.04 - 0.06u and the solid hydrogen mantle radius in the range r = 0.15 - 0.25u. The albedo and phase function of these particles are consistent with the requirements imposed by the diffuse galactic light. Solid hydrogen is strongly anisotropic in its crystal structure and optical properties. Approximate models yield good agreement with the observed trends of the wavelength dependence of interstellar polarisation.
    • Spectroscopy of Outlying Faint Galaxies Near the Coma Cluster

      Tifft, W. G.; Gregory, S. A.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1972-10)
      Redshifts are reported for twenty -seven outlying galaxies in Coma. Twenty -four have redshifts typical for Coma galaxies. Eleven galaxies show emission lines.
    • SSC 08546+1732: A Faint, Dust-Enshrouded Carbon Star at High Galactic Latitude|A Faint, Dust-Enshrouded Carbon Star at High Galactic Latitude

      Cutri, R. M.; Low, F. J.; Kleinmann, S. G.; Olszewski, E. W.; Willner, S. P.; Campbell, B.; Gillett, F. C.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1988-12)
      During the initial phase of a program to search for sub -stellar candidates at high galactic latitudes in the IRAS Serendipitous Survey Catalog, one source, SSC 08546 +1732, was found to have no optical counterpart on the Palomar Observatory Sky Survey plates. Ground based positional, photometric and spectroscopic observations have identified this source as a heavily dust - enshrouded carbon star, similar to those found in the Galactic plane. The high latitude and relative faintness of this source imply that it lies at a distance of 20 - 50 kpc, and is 10 to 30 kpc out of the plane of the Galaxy. SSC 08546 +1732, along with one other distant obscured carbon star found in the IRAS Point Source Catalog (Low 1987; Beichman e1: al. 1988), represent the first examples of such objects found in the Galactic halo. These stars may either have evolved from population I precursors ejected from the disk, or they may be the first obscured Population II halo carbon stars to be observed. A survey for other distant enshrouded carbon stars in the IRAS Faint Source Catalog should help to elucidate the nature of this new population.
    • Statistical Properties of the Lyman-alpha Forest

      Bechtold, J.; Shectman, S. A.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1988-08)
      We have observed two high -redshift quasars with the echelle spectrograph and 2D- Frutti Photon Counter at Las Campanas, in order to investigate the statistical properties of the Lyman -a forest. The two-point correlation function for the Lyman -a forest lines at z .^s 3 is consistent with zero, for all velocity splittings A > 50 km /sec. When Lyman -a lines and other metal lines from known metalline systems are included, the correlation function shows a weak non -zero signal at small A . We suggest that the weak clustering of the Lyman -a forest detected by other workers may be the result of contamination by a small number of metal -line systems and their associated Lyman -a lines.
    • Stimulated Linear Acceleration Radiation: A Pulsar Radio Emission Mechanism

      Cocke, W. J.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1973)
      The Einstein coefficient method is used to calculate the absorption coefficient K for a steady flux of electrons undergoing acceleration in a uniform electric field. Under the approximation that the motion is ultrarelativistic, the emission frequency is low, and the emission direction is nearly parallel to the direction of motion, we find that K is negative for certain emission directions. The formalism is applied to pulsars, and it is shown that strong maser action is expected. If the emission takes place near the velocity -of -light cylinder, the computed collisional Bremsstrahlung may be strong enough to produce the recently observed high- energy Y -rays.
    • Streaming Motions in the Carina-Centaurus Region

      Humphreys, R. M.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1970-09)
      An analysis of new velocity data for a large number of supergiants confirms results presented earlier that streaming motions of 8 km /sec occur between the sides of the spiral feature in the Carina -Centaurus region.