Search Publications
Hubble Space Telescope Space Telescope Imaging Spectrograph Spectroscopy of the Intermediate Polar EX Hydrae
Szkody, Paula; Howell, Steve B.; Sion, Edward M. +2 more
We present the results of our analysis of six orbits of Hubble Space Telescope Space Telescope Imaging Spectrograph (HST/STIS) time-tagged spectroscopy of the intermediate polar, EX Hydrae. The high time and wavelength resolution of the HST/STIS spectra provided an excellent opportunity to study the UV properties of EX Hya. Measurements of the con…
The Kinematics and Physical Conditions of the Ionized Gas in Markarian 509. II. STIS Echelle Observations
Turner, T. J.; Kraemer, S. B.; Crenshaw, D. M. +5 more
We present observations of the UV absorption lines in the luminous Seyfert 1 galaxy Mrk 509, obtained with the medium-resolution (λ/Δλ~40,000) echelle gratings of the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. The spectra reveal the presence of eight kinematic components of absorption in Lyα, C IV, and N V, at radial veloc…
Variable Na I Absorption toward ρ Leonis: Biased Neutral Formation in the Diffuse Interstellar Medium?
Meyer, David M.; Lauroesch, J. T.
We present multiepoch KPNO coudé feed telescope observations of interstellar Na I and Ca II absorption toward the bright star ρ Leo. Comparisons of the Na I profiles observed over a period of 8 yr reveal significant temporal variations in the Na I column in at least one component, implying that there is ``structure'' at scales on the order of the …
The Collimated Wind in NGC 253
Sugai, H.; Davies, R. I.; Ward, M. J.
Near-infrared Fabry-Perot imaging has revealed H2 emission extended to about 130 pc from the disk of NGC 253. It is closely related to the hot plasma observed in soft X-rays: filamentary H2 features are found at the edges of the hot plasma. These are the places of direct interaction between a superwind and its surrounding mol…
Constraints on the Cluster Environments and Hot Spot Magnetic Field Strengths of the Radio Sources 3C 280 and 3C 254
Donahue, Megan; Daly, Ruth A.; Horner, Donald J.
We present new Chandra Observatory observations together with archival Hubble Space Telescope (HST) and radio observations of 3C 254, a radio quasar at z=0.734, and 3C 280, a radio galaxy at z=0.996. We report the detection of X-ray and possible HST optical counterparts to the radio hot spots in 3C 280 and the detection of an X-ray counterpart to …
Mass Motions and Plasma Properties in the 107 K Flare Solar Corona
Curdt, W.; Innes, D. E.; Landi, E. +1 more
In the present work, we analyze Solar Ultraviolet Measurement of Emitted Radiation (SUMER) observations of a solar limb flare that occurred on 1999 May 9. The analyzed data cover a time span of around 6.4 hr, during which an M-7.6 flare erupted and decayed in the field of view. Two selected regions along the SUMER slit have been considered for qua…
Discovery of Radio/X-Ray/Optical-resolved Supernova Remnants in the Center of the Andromeda Galaxy
Kong, A. K. H.; Garcia, M. R.; Williams, B. F. +2 more
We have detected a spatially resolved supernova remnant (SNR) in the center of the Andromeda galaxy, in radio, X-ray, and optical wavelengths. These observations provide the highest spatial resolution imaging of a radio/X-ray/optical SNR in that galaxy to date. The multiwavelength morphology, radio spectral index, X-ray colors, and narrowband opti…
Formation of Minor-Ion Charge States in the Fast Solar Wind: Roles of Differential Flow Speeds of Ions of the Same Element
Chen, Y.; Hu, Y.; Esser, R.
To investigate the possibility of differential flow speeds between ions of the same element and their roles in the determination of ionic fractions, this paper extends our latest minor-ion model to a five-fluid model, describing the behavior of five species of minor ions of one given element in the fast solar wind. We solve the five sets of mass, …
Using Multiwavelength Observations to Determine the Black Hole Mass and Accretion Rate in the Type 1 Seyfert Galaxy NGC 5548
Chiang, James; Blaes, Omer
We model the spectral energy distribution of the type 1 Seyfert galaxy NGC 5548, fitting data from simultaneous optical, UV, and X-ray monitoring observations. We assume a geometry consisting of a hot central Comptonizing region surrounded by a thin accretion disk. The properties of the disk and the hot central region are determined by the feedbac…
A Method for Black Hole Mass Determination in Accretion-powered X-Ray Sources
Titarchuk, Lev; Shrader, Chris R.
We describe a method for the determination of black hole masses based on information inferred from high-energy spectra. It is required that the spectral energy distribution consist of thermal and Comptonized components. One can then, in principle, infer the depth of the gravitational potential well for sources of known distance. The thermal compon…