SPECTROSCOPY OF QUASAR CANDIDATES FROM THE CASE LOW-DISPERSION SURVEYThompson, D. J.; Djorgovski, S.; Weir, W. N.
doi: 10.1086/132577pmid: N/A
Case Low-Dispersion Northern Sky Survey. Thirteen of them are quasars, ranging in redshift from 0.0786 to 2.67, with a median redshift of 2. CSO 203 is a broad absorption-line quasar, and CSO 38 may have substantial associated absorption in the cores of emission lines. Several other objects show some intervening absorption, and all of them are bright enough to make the follow-up studies practical. CSO 251 is a bright (~15m^), previously uncataloged quasar. The remaining objects are Galactic stars, five subdwarfs, and one hot white dwarf (CSO 160).
CAN E AND S0 GALAXIES BE DISTINGUISHED PHOTOMETRICALLY?van den Bergh, Sidney
doi: 10.1086/132578pmid: N/A
Modern CCD photometry of early type galaxies does not allow one to differentiate unambiguously between E and SO galaxies. A de Vaucouleurs law fits the major axis profiles of SO galaxies as frequently as it does those of ellipticals. The data do, however, indicate that exponential disks occur more often in SOs than they do in elliptical galaxies. Furthermore, ellipticals exhibit their maximum flattening at intermediate radii more frequently than do SO galaxies.
THE CN INHOMOGENEITY OF THE GLOBULAR CLUSTER NGC 6637 (M69)Smith, Graeme H.
doi: 10.1086/132581pmid: N/A
Spectra have been obtained of a sample of red giants in the relatively metal-rich disk globular cluster NGC 6637. The distribution of λ4215 CN band strengths is found to be bimodal. Among a sample of 24 stars, the ratio by number of those with strong CN and weak CN bands is found to be 1.0, although there is some uncertainty attached to this value due to the difficulty of identifying potential nonmembers among the observed stars. It is suggested that much higher incidences of CN-strong stars, such as are found in some halo globular clusters, are likely to be rare among the disk population of clusters.
CCD PHOTOMETRY OF THE GLOBULAR CLUSTER NGC 1261Bolte, Michael; Marleau, Francine
doi: 10.1086/132582pmid: N/A
CCD photometry of the halo globular cluster NGC 1261 is presented. This is the first CCD study of the cluster and the first published photometry of main-sequence stars in the cluster. The distance modulus, based on the apparent magnitude of the horizontal branch and the fitting of the main sequence to two subdwarfs, is determined to be (m M) 16.05±0.25. The positions of the NGC 1261 unevolved main sequence, main-sequence turnoff, and subgiant branch are matched well by 15 Gyr isochrones interpolated from the grid of VandenBerg and Bell (1985) for [M/H] 1.09, Y 0.25, and assuming a reddening value toward the cluster of E(B V) 0.02, or by [M/H] -1.27, Y 0.25, 15 Gyr isochrones with E(B -V) 0.04. The color-magnitude diagram (CMD) we measure for NGC 1261 matches in detail that of the "standard" cluster MS indicating that these two clusters have similar values of metallicity and age.
RADIAL VELOCITIES OF MORE OLD OPEN CLUSTERSFriel, Eileen D.; Liu, Tianxing; Janes, Kenneth A.
doi: 10.1086/132583pmid: N/A
Moderate-resolution CCD spectra in the Mg b region of red giants in 13 old or metal-poor open clusters were obtained with the kitt Peak 2.1-m telescope. Radial velocities for these giants, measured by cross-correlation techniques, are accurate to 10 km/s. For the six clusters in the sample with previous measurements, the velocities are in good agreement with published values. Results are presented for seven clusters (NGC 1193, NGC 1817, NGC 6819, NGC 7142, Be 21, King 8, IC 166) with no previous radial-velocity measurements. The majority of clusters in the sample, supplemented with ten more clusters older than 1 Gyr which have published velocities, show radial velocities which are consistent with those expected from the reflex of solar motion and simple galactic rotation. A few of the clusters, including the newly measured NGC 1193 and NGC 1817, show surprisingly large radial velocities, indicating significant deviation from the general rotation of the remaining old cluster system.
ON THE HALO BLUE STAR MYSTERYKraft, Robert P.
doi: 10.1086/132584pmid: N/A
The observed paucity of halo blue stars in comparison with the predictions of the Bahcall-Soneira (B&S) model of the Galaxy is referred to here at the "halo blue-star mystery". We reexamine the basic assumptions of the model, especially the luminosity function adopted by B&S for evolved halo stars. We suggest that the halo blue-star mystery can be resolved by adopting a steeper luminosity function than the one adopted by B&S, viz., one nearer to those observed in M 92, M 13, and the Hartwick field function. With this modification we show that good agreement can be obtained between predicted and observed counts for halo field giants, blue horizontal-branch stars, and RR Lyraes in the south galactic pole, provided a Hess diagram similar to that of M 3 or M 5 is adopted for stars with MV <̃+1.5. There is thus little evidence that the galactic halo field in the range Z ̃ 5 to 20 kpc suffers an extreme second parameter effect, i.e., has a Hess diagram corresponding to such clusters as NGC 7006, Pal 13, or Pal 4 as had been proposed earlier (Kraft 1984).
INFRARED MEASUREMENTS OF METAL-POOR SUBDWARFS AND A COMPARISON WITH MODEL ATMOSPHERESElias, J. H.; Bell, R.; Matthews, K.; Neugebauer, G.
doi: 10.1086/132585pmid: N/A
Infrared observations of four metal-poor subdwarfs have been compared with the predictions of model stellar atmospheres. The parameters of the models were established by fitting observed and calculated spectral energy distributions at visible wavelengths. The models were used to calculate J, H, K, and L-prime apparent magnitudes for the subdwarfs. When compared with observation, it was fount that, while the subdwarf models were internally consistent at the 1-percent level of better, there are systematic deviations relative to Vega in excess of 0.1 mag. These effects are far greater than would be expected from the excellent fits of the models, for both Vega and the subdwarfs, at shorter wavelengths. Various explanations are suggested for this effect.