Publications of the Astronomical Society of the Pacific

Rydgren, A. E.

doi: 10.1086/129617pmid: N/A

The available material on optical and radio spiral tracers in the Norma region (320 < 34O , -5 < b < + 5 ) is reviewed and compared to the spiral structure maps of Kerr (1969) and Courtes et al. (1970). The observations are not entirely consistent with either of these pictures of the spiral structure in this region. Key words: galactic structure - spiral features

Stein, Wayne A.; Ney, Edward P.

doi: 10.1086/129618pmid: N/A

The optical absorptivity of grains of solid material in infrared sources is investigated by the comparison of calculated and observed temperatures and distances of the grains from the source of illumination. It is found that for the few sources for which appropriate measurements have been made the calculated distances of blackbody particles agree well with the measured values - a result which could lead to misleading conclusions about grain properties. The ratio of optical absorptivity to infrared emissivity is calculated for several sources taking into account expected effects of real grain materials. The measured angular size of dust shells surrounding stars can lead to information about the optical properties of grains under astrophysical conditions. Key words: interstellar matter - infrared sources

Krupp, E. C.

doi: 10.1086/129619pmid: N/A

Apparent visual magnitudes and Hubble types are estimated for galaxies with m 16.75 within the 43 clusters of richness class 1 or greater and distance classes 1 through 3 in Abell's statistical sample of rich clusters. The luminosity functions of the E-SO components of 27 of these clusters are fitted together to generate a mean luminosity function for E-SO galaxies in rich clusters, for which relative distances and relative richnesses are obtained. Key words: galaxies - clusters - luminosity function

Catalano, S.; Rodonò, M.

doi: 10.1086/129620pmid: N/A

The orbital period and the light-curve variations of the binary system RS CVn are rediscussed according to a long series of photometric observations made at Catania Observatory since 1963. The period of the migrating wave-like distortion on the light-curve outside eclipses and its role in determining the photometric variations during eclipses are examined. The results obtained make quite improbable Hall's explanations of the erratic changes of the orbital period. Key words: binary systems - orbital period - light-curve variations

Muzzio, J. C.; Marraco, H. G.; Feinstein, A.

doi: 10.1086/129621pmid: N/A

An investigation of OB stars in the Coalsack region is done by means of UBV photographic photometry. The study includes previously known OB stars within a 1 radius circle centered at = 302? 4, b = -0? 2, and newly discovered faint OB stars in five small areas (80 square arc minutes each) within the same circle. Total visual absorption values and minimum distance moduli are derived for all the stars, and the absorption vs. distance modulus diagram is presented. A possible distant OB association is noted in the region sur rounding the compact cluster Hogg 15. Key words: interstellar matter - reddening - OB stars - spiral structure

Robinson, Edward L.; Nather, R. E.; Kiplinger, Alan

doi: 10.1086/129622pmid: N/A

High-speed photometry of the peculiar variable V751 Cyg shows it to display rapid variations, or flickering, similar to that of the cataclysmic variables. V751 Cyg is similar in every respect to vY Scl, and belongs to a very small group of cataclysmic variables which now includes VY Scl, UX UMa, and CO -42 14462. These stars appear to be dwarf novae which are continuously or nearly continuously erupting. Key words: variable star - dwarf nova

Przybylski, A.; Bessell, M. S.

doi: 10.1086/129623pmid: N/A

The high-velocity star HD 202759 is a variable star with an irregular amplitude of about 0 '08 and a quasi-period of about 12 hours. Its surface gravity, log g is 3.1 and its effective temperature 7400 K. It is probably an RR Lyrae star close to the blue edge of the instability strip. Key words: RR Lyrae stars

Bonsack, Walter K.

doi: 10.1086/129624pmid: N/A

Repeated spectrographic observations at dispersions of 11 A and 17 A mm-1 were made of 29 Ap stars located between right ascensions 7h and 19h, and north of declination - 40 . Manganese-type Ap stars were excluded from the survey. The Ap classification of seven of the stars was not confirmed, but of the remaining 22, exactly half proved to be spectrum variables, on the basis of visual inspection of the spectrograms. Equivalent-width measurements were made for the spectrum variables in order to provide quantitative indicators of variability. Examination of the Ap stars in Babcock's list of magnetic stars shows that of those sufficiently well observed to determine variability, 47% are spectrum variables, in agreement with the results of the present observations. The data available are insufficient to determine correlations between the type and degree of spectrum variability and the other properties of the Ap stars. Key words: peculiar A stars - spectrum variables

Brooke, A. L.; Lambert, D. L.; Barnes, T. G.

doi: 10.1086/129625pmid: N/A

Radial velocities obtained from interferometric spectra of a a Ori, a Her, and a Sco have been analyzed to investigate expansion and other large-scale motions in their atmospheres. In a Ori evidence of such motions is found. They appear to be sporadic in time or position on the surface of the star. If these motions are an observational indication of mass loss, they lead to extremely high instantaneous loss rates. It has not been possible to infer an average rate of mass loss. Key words: supergiant - radial velocity - mass loss - infrared - interferometer

Eggen, O. J.

doi: 10.1086/129626pmid: N/A

An apparent clump of M type, HD stars on the border of Carina and Velorum probably results from a rift in the absorption with E(B- V) rising to only at 2 kpc. The 18 M-type stars in the rfft contain 13 new variables of the small-amplitude, semiperiodic type. Key words: stellar clump - interstellar absorption - variable stars