Publications of the Astronomical Society of the Pacific

McClure, R. D.

doi: 10.1086/131310pmid: N/A

The barium stars are Population I G-K giants that have enhanced abundances of carbon and s-process elements, and are probably related in their peculiarities to several other carbon enhanced red-giant types such as CH, R, N, and S stars. Since the abundance anomalies in the barium stars are likely the result of mixing of processed material from deep within a stellar interior, and since they are numerous with many bright examples suitable for detailed observations, these stars provide very valuable information on nucleosynthesis, and the advanced stages of stellar evolution. A clue to the origin of the anomalous abundances in the barium stars is the recent discovery that they are likely all members of binary systems.

Stetson, P. B.

doi: 10.1086/131311pmid: N/A

Giant stars in Draco reveal a wide range of metal abundance as measured by the strengths of Ca II H and K. These range from abundances intermediate between M3 and M92 to abundances much more metal-poor than M92. Draco is found to contain some stars that are much cooler than the giant-branch tip in M92 while being much more metal-poor than stars in M3. On the average, Draco and Ursa Minor giants reveal a systematic enhancement of the G band of CH relative to globular-cluster stars of comparable metallicities and temperatures; some individual stars, however, show G bands appropriate to their metallicities. The systemic radial velocities of Draco and Ursa Minor are determined to be near -296 and -255 km/s, respectively. One star in the Draco field is determined to be a nonmember. All the other stars observed in the Draco field, among them a UV-bright K giant and a blue suprahorizontal-branch star, together with all the stars observed in Ursa Minor, have velocities consistent with membership. The new radial velocities furnish weak evidence against an internal velocity dispersion as great as 10 km/s in Draco.

Willner, S. P.; Fabbiano, G.; Elvis, M.; Ward, M.; Longmore, A.; Lawrence, A.

doi: 10.1086/131312pmid: N/A

Photometry with a small beam size is presented of the nuclei of five spiral galaxies selected for the absence of nuclear activity. No infrared excesses are found, and the color indices of all five galaxies are the same within the uncertainties. The emission of this sample can be explained in terms of a late-type stellar population. These results contrast with earlier results both for Seyfert nuclei and some supposedly normal spiral nuclei, which showed 3.5-μm excesses.

Arp, H.

doi: 10.1086/131313pmid: N/A

It is shown that there is a concentration of radio sources within about 10 degrees of the Local Group galaxy, M33. Many of these radio sources are quasars and radio galaxies with 0.2 ⪉ z ⪉ 0.5. The radio galaxies, having generally narrower emission lines than the quasars, are several magnitudes less luminous thereby suggesting a spectroscopic luminosity criterion. If associated with M33, however, all these objects have very low luminosities. The first quasar discovered, 3C 48 at z = 0.37, is a member of this group and has morphological characteristics of both a galaxy and a quasar. A plot of the brightest apparent magnitude quasars with 0.27 < z < 0.47 in this region of the sky shows they fall in a conspicuous line going through M33. Plots of the brightest apparent magnitude quasars with z ⪉ 0.5 in the opposite direction of the sky show they are generally associated with the nearby galaxies, M82, M101, and NGC 5128. The very brightest quasars in the sky, however, including 3C 273, fall in a direction opposite to the center of the Local Group galaxies. It is concluded they may be in the edge of the Local Group, near our Milky Way galaxy and be the nearest quasars to us.

Vilkki, E. U.

doi: 10.1086/131314pmid: N/A

Three large proper-motion stars have been found to be doubles, components having common proper motion.

Olson, E. C.

doi: 10.1086/131315pmid: N/A

Observations of U Cephei in recent years have shown that transient photometric disturbances can occur at all orbital phases of this active binary (Olson, 1980). Because of this activity, reliable photometric solutions are difficult to obtain. New solutions are attempted using intermediate-band uvby I observations selected from intervals of minimum disturbance. It is shown that large discrepancies are present in both infrared and ultraviolet solutions. The results are compared with three other modern solutions based on broadband photometry. Yellow, blue, and violet observations give the following mean geometrical elements: r1 = 0.183 + or 0.004, b2 = 0.324 + or - 0.002, and i = 85.8 deg + or 0.3 deg. It is pointed out that infrared and ultraviolet elements differ strongly from these mean elements.

Naylor, D. A.; Boreiko, R. T.; Clark, T. A.; Emery, R. J.; Fitton, B.; Kessler, M. F.

doi: 10.1086/131316pmid: N/A

The emission spectrum within the 20-μm window of the atmosphere above Mauna Kea has been measured to a resolution of 0.01 cm-1 with a Michelson interferometer and compared to a single-layer synthetic spectrum in order to test the feasibility of observing fine-structure emission lines from astronomical sources from this site. It is demonstrated that the observed spectrum can be very closely simulated by the inclusion of CO2, H2O, and N2O in the synthetic spectrum, a situation which is presumed to hold for other high, dry observing sites. The present data indicate that large telescopes equipped with high-resolution spectrometers can still be used to advantage in the observation of selected fine-structure lines against the background emission from these sites, particularly when careful background subtraction techniques are used.

Couteau, P.

doi: 10.1086/131317pmid: N/A

We give 155 measures of 63 close binary stars made with the Lick 36-inch (0.9-m) refractor.

Bond, H. E.; Carney, B. W.; Grauer, A. D.

doi: 10.1086/131318pmid: N/A

Photometric monitoring has revealed brightness variations of 0m.1 on a time scale of weeks for HD 46703, a metal-deficient F-type field analog of the stars lying above the horizontal branch in globular clusters. The authors suggest that HD 46703 belongs to the "89 Her" class of luminous F-type variables. Since HD 46703 is unquestionably a halo object, it is almost certainly a low-mass star. The authors suggest that it, and probably the other 89 Her variables, are masquerading as supergiants during their final evolution off the asymptotic giant branch.

Beavers, W. I.; Salzer, J. J.; Shen, L. -Z.

doi: 10.1086/131319pmid: N/A

Orbital elements are determined for the double-line spectroscopic binary HR 362. The elements for the primary component agree well with those determined by Christie (1933), with a revised period of 9.07530 + or - 0.00001 days, and a small but significant eccentricity of 0.040 + or - 0.007. The spectral types of the two components, as indicated by the mass ratio of 1.41 + or - 0.03, are F7 V and G7 V. The system may also exhibit partial eclipses, indicating that the minimum masses of 1.16 + or - 0.04 solar masses and 0.83 + or - 0.02 solar mass are within a few percent of the true masses.