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…
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…
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…
Magellanic Cloud-Type Interstellar Dust along Low-Density Sight Lines in the Galaxy
Gordon, Karl D.; Clayton, Geoffrey C.; Wolff, Michael J.
We have studied the UV extinction properties along 30 Galactic sight lines using data from the International Ultraviolet Explorer archive that have never been previously examined. These distant (d>1 kpc) sight lines were selected to investigate the distribution and physical conditions of gas located in low-density regions of the Galactic disk a…
Theoretical Oscillator Strengths inPr III and Application to Some CP Stars
Quinet, P.; Frémat, Y.; Palmeri, P. +2 more
A set of transition probabilities is obtained for the first time for many transitions of Pr III of astrophysical interest. A relativistic Hartree-Fock method, combined with a least-squares fitting of the available experimental levels, including a large number of newly determined values, has been used for the calculations in which configuration int…
The Structure of Wolf-Rayet Winds. II. Observations of Ionization Stratification in the WN Subtype
Morris, P.; Herald, J. E.; Schulte-Ladbeck, R. E. +1 more
Motivated by the question of the importance of ionization stratification in solving the ``momentum problem'' of Wolf-Rayet stellar winds, we have chosen a sample of 14 WN stars for a systematic study. We performed measurements of the emission line widths on ultraviolet, optical, and infrared spectra to obtain data spanning a large range of ionizat…