Search Publications
Discovery of DampedLyα Systems at Redshifts Less than 1.65 and Results on Their Incidence and Cosmological Mass Density
Turnshek, David A.; Rao, Sandhya M.
We present results from an efficient, nontraditional survey to discover damped Lyα (DLA) absorption systems with neutral hydrogen column densities NHI>=2×1020 atoms cm-2 and redshifts z<1.65. In the past, identification of DLA systems at z<1.65 has been difficult because of their rare incidence and the nee…
A Database of Cepheid Distance Moduli and Tip of the Red Giant Branch, Globular Cluster Luminosity Function, Planetary Nebula Luminosity Function, and Surface Brightness Fluctuation Data Useful for Distance Determinations
Kelson, Daniel D.; Illingworth, Garth D.; Madore, Barry F. +14 more
We present a compilation of Cepheid distance moduli and data for four secondary distance indicators that employ stars in the old stellar populations: the planetary nebula luminosity function (PNLF), the globular cluster luminosity function (GCLF), the tip of the red giant branch (TRGB), and the surface brightness fluctuation (SBF) method. The data…
Models for Old, Metal-Poor Stars with Enhanced α-Element Abundances. II. Their Implications for the Ages of the Galaxy's Globular Clusters and Field Halo Stars
VandenBerg, Don A.
The ages of globular clusters (GCs) and post-turnoff field stars in the Galactic halo are derived using new stellar evolutionary models that explicitly take into account the observed abundances of the α-elements. Whereas the distances of the field subgiants considered in this study are based on Hipparcos parallax measurements, theoretical zero-age…
Low- and High-Ionization Absorption Properties of Mg II Absorption-selected Galaxies at Intermediate Redshifts. I. General Properties
Charlton, Jane C.; Schneider, Donald P.; Steidel, Charles C. +4 more
We present extensive metal-line absorption properties for 45 absorption systems that were selected by their Mg II absorption at redshifts between 0.4 and 1.4. For each system the properties of several chemical species are determined, including a wide range of ionization conditions. In the optical, the absorption systems have been observed at ~6 km…
The Dust-Radio Connection in 3CR Radio Galaxies
Baum, Stefi A.; Miley, George; Sparks, William +6 more
We investigate dust in the nuclear regions of radio galaxies on the basis of 120 images of 3CR radio galaxies in the redshift range 0<z<0.5, taken with the WFPC-2 on the Hubble Space Telescope. At least 40 of these radio galaxies show evidence for absorption due to clumpy dust features; a large range of morphologies is observed for these dus…
An IUE Atlas of Pre-Main-Sequence Stars. I. Co-added Final Archive Spectra from the SWP Camera
Valenti, Jeff A.; Johns-Krull, Christopher M.; Linsky, Jeffrey L.
We have identified 50 T Tauri stars (TTS) and 74 Herbig Ae/Be (HAEBE) stars observed in the IUE short-wavelength bandpass (1150-1980 Å). Each low-resolution (R~6 Å) spectrum was visually inspected for source contamination and data quality, and then all good spectra were combined to form a single time-averaged spectrum for each star. Use of IUE Fin…
Hubble Space Telescope WFPC2 Imaging of a Sample of Early-Type Seyfert Galaxies
Ferruit, Pierre; Mulchaey, John; Wilson, Andrew S.
We have defined a complete sample comprising all 14 Seyfert galaxies in early-type (E, S0, Sa) host galaxies with apparent magnitude mv<14.5 mag and recessional velocity cz<3000 km s-1. This paper presents Hubble Space Telescope (HST) imaging observations of 12 of them, the other two having been observed previously with…
Caltech Faint Galaxy Redshift Survey. IX. Source Detection and Photometry in the Hubble Deep Field Region
Steidel, Charles C.; Hogg, David W.; Neugebauer, Gerry +6 more
Detection and photometry of sources in the Un, G, \Rscr, and Ks bands in a 9×9 arcmin2 region of the sky, centered on the Hubble Deep Field, are described. The data permit construction of complete photometric catalogs to roughly Un=25, G=26, \Rscr=25.5, Ks=20 mag and significant photometric me…
The Local Lyα Forest. I. Observations with the GHRS/G160M on the Hubble Space Telescope
Shull, J. Michael; Stocke, John T.; Penton, Steven V.
We present the target selection, observations, and data reduction and analysis process for a program aimed at discovering numerous, weak (equivalent width <=100 mÅ) Lyα absorption lines in the local universe (0.003<=z<=0.069). The purpose of this program is to study the physical conditions of the local intergalactic medium, including abso…
A Recalibration of IUE NEWSIPS Low-Dispersion Data
Fitzpatrick, E. L.; Massa, D.
While the low-dispersion IUE New Spectroscopic Image Processing System (NEWSIPS) data products represent a significant improvement over original IUE Spectroscopic Image Processing System (SIPS) data, they still contain serious systematic effects which compromise their utility for certain applications. We show that NEWSIPS low-resolution data are i…