Publications of the Astronomical Society of the Pacific

Crawford, D. L.

doi: 10.1086/129796pmid: N/A

Kitt Peak data on 0-type stars have been combined with those of Morrison (1975) to derive interstellar reddening slopes for the uvby system. The results are Ec1 = 0.20 E(b- y), Em1 = -0.32 E(b-y), E(u-b) = 1.5E(b-y),andE(b-y) = 0.74 E(B- V). Key words: 0-type stars - interstellar reddening

Mendoza V., Eugenio E.

doi: 10.1086/129797pmid: N/A

doi: 10.1086/129798pmid: N/A

Cowley, C. R.; Aikman, G. C. L.

doi: 10.1086/129801pmid: N/A

The isotopic shift of the Hg ii 3984 line is examined in the spectra of a number of strong mercury-manganese stars; the shift cannot be explained by line blending with lines of other elements in these stars, but represents real isotopic variations. An astrophysical log gf value of -1.8 is derived for x3984, based on the Hg i x4358 line strength in L CrB and HR 1800. Elemental and (in some cases) isotopic abundances of Hg are derived using a spectrum synthesis technique; overabundances of up to 5.4 dex over the solar system mercury abundance are found; the maximum overabundances may be temperature dependent. Key words: peculiar stars - stellar abundances.

Crampton, D.

doi: 10.1086/129802pmid: N/A

The distance modulus of the young compact cluster Ma 50 is estimated to be i 0.1 from spectroscopic observations of the brighter members. The radial velocity of the cluster is - 81 i 1 km -1 The absolute magnitude of the W-N 4.5 component of HD 219460 is Mv = - i 0.2; it is slightly less luminous than three stars of spectral type B0.5 which have evolved to luminosity class III stars. Key words: Wolf-Rayet stars - open clusters - spectral types - radial velocities

Cowley, A. P.; Houk, N.

doi: 10.1086/129803pmid: N/A

A bright southern B star noted as peculiar from objective-prism plates is found to be rich in Si, Fe, Cr, and Ti but deficient in He. Key words: spectroscopy - peculiar stars

Hutchings, J. B.

doi: 10.1086/129804pmid: N/A

In order to review the basic data on very massive stars, masses and radii are presented for all well-determined binaries of spectral type O and early B. These are derived from spectroscopic and photometric orbital parameters, in many cases using results and methods available in the last few years. The masses are consistent with those recently derived for single stars by Conti and Burnichon, which imply that Of star masses may exceed 60 solar masses. Relationships between masses, temperatures, and radii are given, and compared with those for X-ray binaries.

Kemper, E.

doi: 10.1086/129805pmid: N/A

Absolute magnitudes of Ba II stars determined from the width of Ha indicate that these stars have, on the average, the luminosity of normal G and K giants. There may, however, be some Ba stars of luminosity class IV. The distribution of stars in absolute magnitude does not seem to depend on Ba line strength. Key words: barium stars - absolute magnitudes - Ha line widths

Gudehus, D. H.

doi: 10.1086/129806pmid: N/A

Optimum entrance apertures, based upon signal-to-noise ratio considerations, are derived for spectroscopy of redshifted galaxies. Signal-to-noise ratio is found to decrease slowly for apertures larger than optimum and to depend strongly on redshift. The optimum apertures decrease with increasing redshift and depend slightly on the deceleration parameter.

Arp, Halton

doi: 10.1086/129807pmid: N/A

Photographs on IIIa-J plates show more detail and fainter features than sdo recent observations of the same objects with the spectracon. It is ssuggested that the radio source 3C 120 is some form of a spiral galaxy. sThis conclusion is in contradiction to that of Walker, Pike, and McGee s1974b. Key words: spiral galaxies - quasars - Seyfert galaxies