Search Publications
Far-Infrared Galaxies in the Far-Ultraviolet
Sanders, D. B.; Steidel, Charles C.; Heckman, Timothy M. +4 more
In an effort to better understand the UV properties of ultraluminous infrared galaxies (ULIGs), and compare them to the rest-frame UV properties of high redshift submillimeter and Lyman-break galaxies, we have obtained far- and near-UV imaging observations (λeff=1457 and 2364 Å, respectively) of two luminous infrared galaxies (LIGs-VV 1…
Revised Stellar Temperatures for Magellanic Cloud O Supergiants from Far Ultraviolet Spectroscopic Explorer and Very Large Telescope UV-Visual Echelle Spectrograph Spectroscopy
Hillier, D. J.; Crowther, P. A.; Willis, A. J. +3 more
We have undertaken quantitative analysis of four LMC and SMC O4-9.7 extreme supergiants using far-ultraviolet FUSE, ultraviolet IUE/Hubble Space Telescope, and optical Very Large Telescope UV-Visual Echelle Spectrograph spectroscopy. Extended, non-LTE model atmospheres that allow for the consistent treatment of line blanketing, developed by Hillie…
Steps toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XVI. A 13 Year Study of Spectral Variability in NGC 5548
Filippenko, A. V.; Shapovalova, A. I.; Chavushyan, V. H. +38 more
We present the final installment of an intensive 13 year study of variations of the optical continuum and broad Hβ emission line in the Seyfert 1 galaxy NGC 5548. The database consists of 1530 optical continuum measurements and 1248 Hβ measurements. The Hβ variations follow the continuum variations closely, with a typical time delay of about 20 da…
The Mass of the Central Black Hole in the Seyfert Galaxy NGC 3783
Peterson, Bradley M.; Onken, Christopher A.
Improved analysis of ultraviolet and optical monitoring data on the Seyfert 1 galaxy NGC 3783 provides evidence for the existence of a supermassive, (8.7+/-1.1)×106Msolar, black hole in this galaxy. By using recalibrated spectra from the International Ultraviolet Explorer satellite and ground-based optical data, as well as re…
The Luminosity Dependence of Ultraviolet Absorption in Active Galactic Nuclei
Brandt, W. N.; Laor, Ari
We describe the results of a survey of the UV absorption properties of the Boroson & Green sample of active galactic nuclei (AGNs), which extends from the Seyfert (MV~=-21) to the luminous quasar (MV~=-27) level. The survey is based mostly on Hubble Space Telescope archival data available for >~1/2 of the 87 sample obj…
Variability of Southern T Tauri Stars. II. The Spectral Variability of the Classical T Tauri Star TW Hydrae
Alencar, Silvia H. P.; Batalha, Celso
We present the analysis of 42 spectra of the Classical T Tauri star TW Hya observed with the FEROS echelle spectrograph over 2 yr. We determined the rotational and radial velocities of TW Hya, obtaining vsini=5+/-2 km s-1 and vrad=12.5+/-0.5 km s-1. The star exhibits strong emission lines that show substantial vari…
The Variability of the Hg II λ3984 Line of the Mercury-Manganese Star α Andromedae
Adelman, Saul J.; Gulliver, Austin F.; Kochukhov, Oleg P. +1 more
The variability of the Hg II λ3984 line in the primary of the binary star α And was discovered through the examination of high-dispersion spectra with signal-to-noise ratios greater than 500. This first definitively identified spectrum variation in any mercury-manganese star is not due to the orbital motion of the companion. Rather, the variation …
The Spectral Components of SS 433
Wang, Z.; Gies, D. R.; McSwain, M. V. +3 more
We present results from new optical and UV spectroscopy of the unusual binary system SS 433, and we discuss the relationship of the particular spectral components that we observe to the properties of the binary. These spectral components include1. The continuum spectrum, which we associate with flux from the super-Eddington accretion disk and the …
A Study of π Aquarii during a Quasi-normal Star Phase: Refined Fundamental Parameters and Evidence for Binarity
Bjorkman, Karen S.; Miroshnichenko, Anatoly S.; McDavid, David +1 more
We present the results of recent multicolor photometric and high-resolution spectroscopic observations of the bright Be star π Aqr. Observational data collected from the literature were used to study the star's variations over the last four decades. The star is identified with the IR sources F22227+0107 in the IRAS Faint Point Source Catalog and M…
The Effective Temperatures of Mid-O Stars
Bianchi, Luciana; Garcia, Miriam
We derived photospheric parameters, mass-loss rates, and wind velocities of Galactic O6-O7 stars by analyzing high-resolution spectra in the far-UV and UV ranges with line-blanketed, hydrodynamic, non-LTE spherical models. We combined spectra from the Far Ultraviolet Spectroscopic Explorer (FUSE) in the range 905-1187 Å and International Ultraviol…