Search Publications
On the Absence of Broad Mg II Emission Line Variability in NGC 3516 during 1996
Koratkar, A. P.; Korista, K. T.; O'Brien, P. T. +2 more
During the 1996 Hubble Space Telescope/Faint Object Spectrograph monitoring campaign of the Seyfert 1 galaxy NGC 3516, the UV continuum showed a factor of 5 variation; correspondingly, the strongest broad UV emission lines (e.g., Lyα, C IV) displayed somewhat weaker, although still significant, variations (a factor of 2). In contrast, no variation…
The Closest Damped Lyα System
Miller, Eric D.; Bregman, Joel N.; Knezek, Patricia M.
A difficulty of studying damped Lyα systems is that they are distant, so one knows little about the interstellar medium of the galaxy. Here we report on a damped Lyα system in the nearby galaxy NGC 4203, which is so close (vhelio=1117 km s-1) and bright (B0=11.62) that its H I disk has been mapped. The absorption l…
The HUBBLE SPACE TELESCOPE Extragalactic Distance Scale Key Project. XXIII. The Discovery of Cepheids in NGC 3319
Illingworth, Garth D.; Huchra, John P.; Kennicutt, Robert C. +21 more
The distance to NGC 3319 has been determined from Cepheid variable stars as part of the Hubble Space Telescope Key Project on the Extragalactic Distance Scale. Thirteen and four epochs of observations, using filters F555W (V) and F814W (I), respectively, were made with the Wide Field Planetary Camera 2. Thirty-three Cepheid variables between perio…
ORFEUS II and IUE Spectroscopy of EX Hydrae
Mauche, Christopher W.
Using five high-resolution (λ/Δλ~3000) FUV (910-1210 Å) spectra acquired in 1996 December during the flight of the ORFEUS-SPAS II mission, 47 archival IUE short-wavelength UV (1150-1950 Å) spectra, and archival EUVE deep survey photometry (70-200 Å), we present a detailed picture of the behavior of the magnetic cataclysmic variable EX Hydrae in th…
Two-Temperature Coronal Models from SOHO/EIT Observations
Zhang, J.; Kundu, M. R.; White, S. M.
We present a method for deriving a two-thermal-component approximation to the differential emission measure distribution of plasma in the Sun's corona in the temperature range to which the Extreme-Ultraviolet Imaging Telescope (EIT) on the Solar and Heliospheric Observatory (SOHO) spacecraft is sensitive. EIT takes high-resolution full-disk corona…
Dust Lanes Causing Structure in the Extended Narrow-Line Region of Early-Type Seyfert Galaxies
Rieke, G. H.; Alonso-Herrero, A.; Quillen, A. C. +3 more
We construct near-infrared to visible broadband NICMOS/WFPC color maps for four early-type Seyfert galaxies with S-shaped or one-sided ionization cones. We find that dust lanes are near or connected to many of the features seen in the [O III] and Hα + [N II] line emission maps. This suggests that much of the structure of line emission in these ion…
How Saturated Are Absorption Lines in the Broad Absorption Line Quasar PG 1411+442?
Matsuoka, M.; Brinkmann, W.; Wang, J. X. +1 more
Recently, convincing evidence was found for extremely large X-ray absorption by column densities greater than 1023 cm-2 in broad absorption line quasars. One consequence of this is that any soft X-ray emission from these QSOs would be the scattered light or leaked light from partially covering absorbing material. A detection …
The Evolution of the Galaxy Sizes in the New Technology Telescope Deep Field: A Comparison with Cold Dark Matter Models
Fontana, A.; Giallongo, E.; Menci, N. +2 more
The sizes of the field galaxies with I<=25 have been measured in the New Technology Telescope (NTT) Deep Field. Intrinsic sizes have been obtained after deconvolution of the point-spread function with a multi-Gaussian method. The reliability of the method has been tested using both simulated data and Hubble Space Telescope (HST) observations of…
Phase and Amplitude Difference between Velocity and Intensity Helioseismic Spectra
Kosovichev, A. G.; Nigam, R.
An explanation for the phase and amplitude difference between velocity and intensity oscillations of the Sun is provided. The phase difference along the modal lines in the power spectra was originally observed by Deubner and coworkers in 1989. From a simple adiabatic theory of solar oscillations, one expects this phase difference to be 90° for mod…
A Search for Microflaring Activity on DME Flare Stars. II. Observations of YZ Canis Minoris
Carpenter, K. G.; Robinson, R. D.; Percival, J. W.
We report on time-series photometric observations of the dM4.5e flare star YZ Canis Minoris obtained in 1993 November with the High Speed Photometer on board the Hubble Space Telescope. The data consist of five 30 minute time sequences with a sampling rate of 0.01 s that were taken through the F240W filter (centered at 240 nm with an 80 nm width).…