Publications of the Astronomical Society of the Pacific

de Vaucouleurs, G.

doi: 10.1086/129088pmid: N/A

The nonrandom clustering of galaxies and clusters of galaxies has attracted increasing attention in the past 40 years. The mathematical tests and criteria used to distinguish between an observed distribution and a Poisson, i.e., random, statistically uniform distribution, are outlined. The observational evidence for (and against) hierarchical clustering of galaxies and clusters on various characteristic length scales A from 0.1 Mpc to at least 100 Mpc, is reviewed. Some cosmological implications and possible origins of the clustering spectrum are discussed. Key words: galaxies - clusters of galaxies 1. Introduction 2. Subclustering: pairs and multiplets (A 0.1 Mpc) 3. Small-scale clustering: groups and small clusters (A 1 Mpc) 4. Statistical principles 5. Index of dumpiness and dispersion-subdivision curves 6. Correlation techniques and power spectrum analysis 7. Galactic absorption effects A. Average effects B. Fluctuation effects 8. Medium-scale clustering: large clusters, cloud complexes, and superclusters (A 10 Mpc) 9. The distribution of rich clusters A. The Zwicky Catalog B. The Abell Catalog 10.Large-scale clustering and density gradients (A 100 Mpc) 11.Galaxy clustering and the density-radius relation 12.The spectrum of clustering and its origin

Plavec, Miroslav

doi: 10.1086/129089pmid: N/A

Statistical considerations indicate that a nonnegligible fraction of apparently single mainsequence stars earlier than AS should actually be the more massive components of binaries in which a large-scale mass exchange has occurred (van den Heuvel 1969). It is rather difficult to identif these objects. If the -mechanism as proposed by Stothers and Simon (1969) were the correct explanation of the fi Cephei phenomenon, then this phenomenon would identify one class of these transformed binaries. From known models of mass exchange, some conditions are derived that should be fulfilled by binaries if they are to display the -mechanism. Most of the stars in the list by Stothers and Simon (1970) do not seem to meet these conditions. If some of them are found to be P Cep variables, then either the -mechanism or the models of mass exchange will have to be revised. It is suggested that certain peculiar binaries and shell stars (and possibly also symbiotic variables) are binaries observed at the stage of mass exchange or mass loss. Key words: P Cephei variable stars - mass exchange

Batten, A. H.; Fletcher, J. M.; West, F. R.

doi: 10.1086/129090pmid: N/A

The suspected resolution of the spectra of the components of the visual binary star 2173, which West reported in 1966, has been confirmed on five high-dispersion (2.5 mm) spectrograms obtained at Victoria in 1968 and 1969. In 1968 the radial-velocity difference was about 10.6 kinisec. West's original measures are revised and discussed together with the new data. The magnitude difference, by Petrie's method, from two of the Victoria spectrograms is = i 0.004 (m.e.). The adopted masses are 1.14o and 1.08e. The node at 153 position angle is identified as the ascending node. Key words: visual binaries - spectroscopic binaries - stellar masses

Philip, A. G. Davis

doi: 10.1086/129091pmid: N/A

Four-color and H photometry of M 4-307, a star located above the horizontal branch in the color-magnitude diagram of M 4, shows that it is a foreground object with a spectral type of F4. A spectrum obtained with the Carnegie image tube on the 84-inch telescope confirms the spectral type. The radial velocity measured from the spectrum is -26 km/sec which is quite different from the cluster velocity of + 65 km/sec. Key words': horizontal branch star? photometry

Morbey, C. L.; Hutchings, J. B.

doi: 10.1086/129092pmid: N/A

Observations of lunar occultations have been made with a time resolution of one millisecond at the Dominion Astrophysical Observatory. A computer program has been written which compares theoretical and observed diffraction patterns and gives a least squares best fit in terms of the angular diameter of the star and the slope of the lunar limb. Key words: lunar occultations - stellar radii

Peery, Benjamin F.

doi: 10.1086/129093pmid: N/A

Arguments in favor of the correctness of the identification of technetium in stellar spectra are: (1) wavelength coincidences and relative strengths compared with the 13 strongest laboratory Tc lines in the violet; (2) preservation of the proper relative strengths among the lines from star to star, irrespective of the prominence or faintness of the set; (3) the appearance of lines identified with Tc only in stars with over-abundant s-process elements that peak near the neutron magic-number 50. Key words: technetium in stars - 5 process - N-type stars - stellar spectra

Hobbs, R. W.; Waak, J. A.

doi: 10.1086/129094pmid: N/A

Planetary nebulae IC 418, NGC 6857, and NGC 7027 have been measured at 2.73, 1.65, and 0.95 cm wavelengths. Flux densities were measured by reference to Jupiter. The source near NGC 6857 is extended and has the spectrum to be expected from a composite thermal source. The spectrum is nearly flat near 1 cm, indicating that all components have become optically thin by this wavelength. NGC 7027 and IC 418 have typical thermal spectra, and are optically thin at all three wavelengths. Key words: planetary nebulae - radio astronomy - H ii regions

Viotti, R.

doi: 10.1086/129095pmid: N/A

The photometric and spectroscopic observations of the P Cygni-type stars AG and HR Carinae are discussed, and compared with Car and P Cyg. It is concluded that both are very luminous stars which are suffering large mass loss. Key words: P Cygni stars - mass loss

Hesser, James E.; Henry, Richard C.

doi: 10.1086/129096pmid: N/A

Narrow-band photoelectric photometry of the K line of calcium has been obtained for the A stars of five galactic clusters. The 38 stars measured in NGC 6475 (M 7) exhibit a range in calcium abundance of only I 25 percent, rather than the factor-of-two variation observed for field stars. This suggests that the interstellar cloud from which NGC 6475 was formed was similarly homogeneous in calcium and, presumably, other metals. In addition, we comment on suspected metallic-line stars in NGC 6475, IC 2391, the Hyades, and the Pleiades. Key words: photometry - star clusters - metal abundance - metallic-line stars

Walker, R. L.

doi: 10.1086/129097pmid: N/A

Photoelectric UBV photometry for 173 PZT stars has been completed and the results are presented in this paper. These observations complete UBV photometry for stars in the PzT catalogs nsed by the U. S. Naval Observatory. Key words: photometry - photographic zenith telescope stars